Junos routing overview from Juniper

Juniper Networks
Networking Essentials
Module 1: TCP/IP Internetworking
Copyright © 2003, Juniper Networks, Inc. IJNR-6.b.6.1.2

Module Objectives
After successfully completing this module, you will be
able to:
– Identify the components of an internetwork and explain the
role of each component
– Explain how packets are routed on a TCP/IP network
– Describe the role of an IP address on an internetwork
Copyright © 2003, Juniper Networks,
Inc.

Internetwork Example
Network 1
192.168.1.0
Network 2
192.168.2.0
Inc.

Local-Area Networks
A computer network that spans a small area
Confined to a single building or corporate campus
Can connect to other LANs through telephone lines
and wireless connections
LAN characteristics differentiated by:
– Topology
– Protocols
– Media
Inc.

Wide-Area Networks
A computer network that spans a large geographical
area
WANs interconnect LANs
Computers connected to WAN through public
telephone system, leased lines, or wireless connection
The Internet consists of many WANs and WAN links
Inc.

Intermediate Internetworking Devices
Inc.
Bridges
– Connect multiple LAN segments to form a larger LAN
 Usually the same media type
– Bridges forward broadcasts by default
Routers
– Connect multiple LANs but maintain LAN boundaries
– Connect LANs across WAN links
 LAN and WAN links may be different media types
– Implement logical network structure (e.g., IP networks)
– Routers block broadcasts by default
Switches
– High-speed multi-port bridges with many ports
– Many implement Virtual LANs (VLANs)

Routing on a TCP/IP Network
Network 2
192.168.2.0
Network 1
192.168.1.0
Inc.

Role of IP and the IP Address
End-to-End Delivery
IP Protocol Internet (IP) IP Protocol
Inc.
Application
TCP/UDP
IP Address X
Application
TCP/UDP
IP Address Y
Network-Dependent Network-Dependent

Format of the IP Address
IP address is a 32-bit numeric address
Written as four numbers separated by periods:
– ‘Dotted Quad’ notation for human convenience
– Examples
 10.0.15.1
 172.20.10.24
 192.168.94.122
The IP address is used to identify a particular network
and host on that network
– Must be globally unique (with some exceptions)
Inc.

Relationship of the IP Address to the
Hardware Address
Application
Presentation
Session
Transport
Network
MAC
Physical
OSI Reference Model
802.2 Logical Link Control
Inc.
7
6
5
4
3
2
1
LLC
802.3
CSMA/CD
802.4
Token Bus
802.5
Token Ring
IP Address

Mapping Address Layers: ARP
Address Resolution Protocol (ARP) maps an IP address
to a physical MAC address
– Host broadcasts an ARP request to obtain a physical address
IP: 192.168.2.1
MAC: 0000.2222.1111
IP: 192.168.2.23
MAC: 0000.2222.2323
(1) Requester sends
BROADCAST ARP_REQUEST
(MAC dest = ffff.ffff.ffff, target
IP = 192.168.2.23)
IP: 192.168.2.2
(2) ALL hosts read
ARP_REQUEST, but do not
respond if they’re not the
MAC: 0000.2222.2222
IP: 192.168.2.11
MAC: 0000.2222.0011
IP: 192.168.2.43
MAC: 0000.2222.4343
Inc.
target
(3) Target host responds to
requester via UNICAST
(192.168.2.23 maps to MAC
0000.2222.2323, MAC dest =
0000.2222.1111)
(4) Requester stores the
mapping in local ARP cache
and can now communicate
directly with target

Logical Network Types
Inc.
 Broadcast
– Multiple sources and
destinations "on the wire"
– One packet can be read by
many receivers
– Typical for LANs
– Example: Ethernet
 Point-to-Point
– Two ends/"stations"
– Typical for WANs
– Example: T1
Router A Router B

Review Questions
1. How does a router differ from a bridge?
2. What is ARP?
3. What are two types of Logical Networks?
Inc.

Juniper Networks
Module 2: IP Addressing
.

Module Objectives
After successfully completing this module, you will be
able to:
– Create IP addresses in binary notation and decimal format,
and identify the corresponding address classes
– Define subnetting and subnet masks, and create effective
subnets for a given network
– Define classless interdomain routing (CIDR), and aggregate a
given range of network addresses to the highest degree
possible
Inc.

Importance of IP Addressing
Unique addresses make information delivery systems
work
– Telephone numbers
– Postal addresses
IP addressing scheme integral to process of routing IP
data through an internetwork
Two major Internet scaling issues:
– IPv4 address space depletion
– Routing traffic given increasing number of networks that
make up the Internet
Inc.

Classful IP Addressing
Original Classful IP addressing defines a 32-bit IP
address
Two-part Internet address structure
32-Bit IP Address
Network Part Host Part
Inc.

Binary Overview
7 6 5 4 3 2 1 0 Bit position
27 26 25 24 23 22 21 20 2^(bit position)
Inc.
128
64
32
16
8 4 2 1 Decimal value
1 0 0 1 1 0 1 0 128+16+8+2=154
0 0 0 1 0 1 1 1 16+4+2+1=23
1 1 1 0 1 0 0 0 128+64+32+8=232
0 1 0 0 0 0 0 1 64+1=65
1 1 1 1 1 1 1 1 128+64+32+16+8+4+2+1=255
1 0 1 0 1 1 0 0 128+32+8+4=172

Primary Address Classes
Network Host Host
128 64 32 16 8 4 2 1
1 0 Network
Inc.
Host
8
Host
16
Host
24
Host
Network
Network Network
0
1 1 0 Network
24
16
8
No. of bits
Class A
Class B
Class C

Dotted Decimal Notation
Bit# 31 0
. . .
10101100 00010000 00100011 00001000
172 16 35 8
172.16.35.8
Inc.

High-Order Bits
 Class addresses specified by the high-order bits:
Class High-Order Bits
Class A 0
Class B 10
Class C 110
 IP Address 192.168.21.40 is a Class C address:
11000000.10101000.00010101.00101000
Inc.

First Octet Rule
Class determined by location of first 0 in binary
address:
Class First Octet Range
Class A 00000001 – 01111110 (Binary)
1 – 126* (Decimal)
Class B 10000000 – 10111111
128 – 191
Class C 11000000 – 11011111
192 – 223
*0 and 127 reserved
Inc.

First Octet Rule Examples
Address Class
172. 18.192.34
10101100.00010010.11000000.00100010
Inc.
B
10.155.128.2
00001010.10011011.10000000.00000010
A
192.12.3.42
11000000.00001100.00000011.00101010
C

Default Masks
Identify the location of the network part (1s) and host
part (0s) of an address
Class A 11111111.00000000.00000000.00000000
255 . 0 . 0 . 0
Class B 11111111.11111111.00000000.00000000
255 . 255 . 0 . 0
Class C 11111111.11111111.11111111.00000000
255 . 255 . 255 . 0
Inc.

Reserved Addresses
Network Address: all host bits are binary 0
– 10.0.0.0
– 172.23.0.0
– 192.168.14.0
Broadcast Address: all host bits are binary 1
– 10.255.255.255
– 172.23.255.255
– 192.168.14.255
Inc.

IPv4 Address Management Issues
Central authority: IANA
Inefficient allocation of limited address space
IPv4 32-bit address space
Address allocations based on organizations requests
rather than actual need
Early depletion of Class B addresses
Inc.

IP Subnetting
All Classful IP addresses can be divided into smaller
networks called subnets
Class B Address: Before Subnetting
1 0 Network Network Host Host
Class B Address: After Subnetting
1 0 Network Network Subnet Host
Inc.

Problems Solved with Subnetting
Provides network administrators with extra flexibility
Provides more efficient use of network address
utilization
Contains broadcast traffic; broadcast will not cross a
router
Subnets under local administrator control
External users and organizations see only single
network
Inc.

Subnet Mask
Example subnet mask for Class B address
Network Network Subnet Host
Binary 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0
Inc.
Representation
Dotted Decimal
Representation 255 . 255 . 255 . 0

Subnet Example 1
Assigned Network Number: 172.25.0.0/16
Create 256 subnets
– 172.25.0.0/24
– 172.25.1.0/24
– 172.25.2.0/24
– 172.25.3.0/24
– .
– .
– .
– 172.25.255.0/24
Inc.

Subnet Example 2
Create 4 subnets
– 192.168.1.0/26
– 192.168.1.64/26
– 192.168.1.128/26
– 192.168.1.192/26
Inc.

Subnet Example 3
Create 8 subnets
– 10.0.0.0/11
– 10.32.0.0/11
– 10.64.0.0/11
– 10.96.0.0/11
– 10.128.0.0/11
– 10.160.0.0/11
– 10.192.0.0/11
– 10.224.0.0/11
Inc.

Growth of the Internet
The Internet is today’s largest public data network
Connects millions of users worldwide
Ongoing technical advancements in networking
hardware contribute to growth
Increasing number of networks over the past decade
Inc.

Growth of Internet Routing Tables
Caused by Internet expansion
Backbone routers must maintain complete Internet
routing information
Additional factors include:
– Increased CPU processing speed for routing table topology
updates
– Dynamic nature of today’s WWW
– Increased volume of diverse information
IP Next Generation (IPv6)
– Long-term solution, but deployment is limited
IPv4 modified to allow continued growth
Inc.

Classless Inter-Domain Routing
CIDR ignores the concept of Network Address Classes
Reduces the amount of route advertisements
No CIDR
192.168.64 /24
192.168.65 /24
CIDR
Inc.
192.168.64 /22
192.168.64.0
.65.0
.66.0
.67.0
192.168.66 /24
192.168.67 /24

Implications of CIDR on the Router
CIDR officially documented in 1993
CIDR supports following important features that benefit
global Internet routing system:
– Ignores traditional concept of Class A, B, and C network
addresses
– Supports route aggregation where single routing table entry
can represent address space of thousands of traditional
classful routes
Inc.

CIDR Address Allocation Example
Allocate variable-length blocks from 192.168.16/20
Block
#1
Block
#4
Block
#3
Inc.
192.168.16.0/21
192.168.30.0/23
192.168.28.0/23
192.168.24.0/22
Block
#2

CIDR Routing in a Classless Environment
ISP 1
Inc.
Internet
Organization 2
172.25.24.0/22
ISP 2
192.168.0.0/16
172.16.0.0/16
Organization 1
172.25.16.0/21
Organization 4
172.25.30.0/23
Organization 3
172.25.28.0/23

JUNOS Support for CIDR
JUNOS supports CIDR
Defined in RFC 1519, Classless Inter-Domain Routing
(CIDR): An Address Assignment and Aggregation
Strategy
Inc.

Private IP Addresses (RFC 1918)
Sustained growth in TCP/IP technology
Increasing number of enterprises use TCP/IP for intra-enterprise
communications only
Concerns:
– Limited global address space
– Routing overhead increasing beyond capabilities of ISPs
RFC1918 allows enterprises and ISPs to use specific
address space so long as it is not advertised back out
to the Internet
– 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16
ISPs continue to obtain blocks of public address space
from address registry and assign customers addresses
from within block based on customer requirement
Inc.

Review Questions
1. To select IP addresses for an ISP, where would you
Inc.
begin?
2. How are subnets implemented on an IP network?
3. When would you implement CIDR on an IP network?
4. What is the purpose of Private Addressing and how is
it useful?

Lab 1: IP Subnetting
Note: Various Junos CLI commands will be used during
this lab that have not yet been discussed. All CLI
commands will be fully explained in the sunsequent
sections.
Inc.

Juniper Networks
Module 3: Router Basics

Module Objectives
After successfully completing this module, you should
be able to:
– Describe the function of a router and explain how a router
works to route packets on a network
– Explain the concepts of routing metrics and route selection on
an Internet network
Inc.

What Is Routing?
Act of moving information across logical path from a
source to a destination
Routers
– Determine the best routing paths
– Transport information groups, or packets, through an
internetwork
Routers vs. bridges and switches
– Bridges and switches operate at Layer 2, the Data Link layer
– Routers operate at Layer 3 (the Network layer)
Inc.

Basic Router Functions
Route determination/topology awareness
– Routes are learned and recorded in the route table
– Selection criteria are applied to determine the preferred route
or routes to each destination
– The preferred routes are recorded in the forwarding table
Packet forwarding
– Incoming packets are switched to outgoing interfaces based
on the forwarding table entries
Inc.

How Routers Operate
Application Layer
Consists of applications and
processes that use the network
Host-to-Host Transport Layer
Internetwork Layer
Frames are switched from one
interface to another, based on
packet information
Network Access Layer
Identifies bits on the medium
at router interfaces
Select interface to
which to send
encapsulated frames
Encapsulate frames
(such as Ethernet)
Transmit bits of the frame
Inc.
4
3
2
1

Packet Processing
Packet
(2) IP lookup (3) Select outbound interface
(1) Inbound:
• Receive bits
• Detect frame
• Remove
encapsulation
(4) Outbound:
• Re-encapsulate
• Transmit bits
1. Receive packet, check L2 info.
2. Read L3 header to determine destination address.
3. Perform longest-match lookup for L3 destination in
forwarding table and select the appropriate outbound physical
interface.
4. Encapsulate the packet with the appropriate L2 header/trailer
and transmit.
Inc.
5. GO TO STEP 1: Receiving router does it all over again.…

IP Packet Format
Router reads
destination
address to determine
how to route the packet
32 BITS
VERSION IHL TYPE-OF-SERVICE
TOTAL LENGTH
IDENTIFICATION FLAGS FRAGMENT OFFSET
TIME-TO-LIVE PROTOCOL HEADER CHECKSUM
SOURCE ADDRESS
DESTINATION ADDRESS
OPTIONS (+ PADDING)
DATA (VARIABLE)
Inc.

IP Addresses Determine Route Destination
24
Class A Network Host Host Host
16
128 64 32 16 8 4 2 1
Class B Network Network Host Host
Class C Network Network Network Host
What is the longest-match
prefix for this packet?
Inc.
8
14
21
No. Bits 7
0
1 0
1 1 0

Selecting Routes for Forwarding
Routing
updates
Static
routes
Local
addresses
Routing
Table
Inc.
Policy
Forwarding
Table
Best Yes
Routes

Routing Tables
Packet’s destination address is for:
– One of the router’s interfaces or a broadcast address
 Packet is for an internal router process
– Any other known address
 Packet must be routed
– Unknown address
 Look for default route. If none exists, packet is dropped
Packet In Packet Out
Inc.

Contents of a Routing Table
Minimum contents of routing table:
– Destination prefix
– Next-hop IP address
 The next router downstream, closer to the destination
inet.0: 12 destinations, 12 routes (12 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.21.0/24 *[Direct/0] 17:48:31 > via GigE0.0
10.0.21.2/32 *[Local/0] 17:48:31 Local
10.0.29.0/24 *[Direct/0] 17:48:31 > via GigE1.0
10.0.29.1/32 *[Local/0] 17:48:31 Local
192.168.16.0/24 *[RIP/100] 00:03:45 > to 10.0.21.1 via fxp0.0
192.168.17.0/24 *[RIP/100] 00:03:45 > to 10.0.21.1 via fxp0.0
192.168.28.0/24 *[Static/5] 16:48:05 Discard
192.168.29.0/24 *[Static/5] 16:48:05 Discard
Inc.

Populating a Routing Table
Static and default routes
– Specific prefixes not learned via a protocol
– Default used when a partial match cannot be made
Dynamic routing protocols
– Routers communicate reachability information
inet.0: 7 destinations, 7 routes (7 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.21.0/24 *[Direct/0] 01:00:31 > via GigE0.0
10.0.21.2/32 *[Local/0] 01:00:31 Local
10.0.29.0/24 *[Direct/0] 01:00:31 > via GigE1.0
10.0.29.1/32 *[Local/0] 01:00:31 Local
192.168.16.0/24 *[RIP/100] 00:03:45 > to 10.0.21.1 via GigE0.0
Inc.

Route Selection
Route selection is based on:
– Longest, or most specific, match
– Preferences, for different protocols
– Routing metrics, for same protocol
Given multiple routes to a destination, the router must
select the best route
Load balancing may be considered
Inc.

Route Selection: Longest Match
Most specific address is matched:
– Host route
– Subnet
– Summary route, or group of subnets
– Major network number
– Supernet, or group of major networks
– Default address
Inc.

Route Selection: Preference
Routing protocol processes calculate the active route
from all routes in the routing table
Preference routes are placed in the forwarding table
The active route is the route with the lowest preference
value
– Preference is a value in the range of 0 through 255
– Preference is used to rank routes received from different
protocols, interfaces, or remote systems
Identifies the believability of a source in determining
best route
Inc.

Route Selection: Routing Metrics
Routing metrics are generally a measurement of cost or
overhead
Metrics are protocol-specific
– Used to determine the best route for a single protocol
– Don’t compare metrics from different routing protocols—
apples vs. oranges
Inc.

Forwarding Table
nancy@sluggo.lab> show route forwarding-table
Internet:
Destination Type RtRef Nexthop Type Index NhRef Netif
10.100.71.0/24 user 0 10.100.67.254 ucst 18 74212 GigE0.0
10.100.71.224/27 user 2 10.100.67.254 ucst 18 74212 GigE0.0
10.250.1.36/30 intf 0 ff.3.0.21 ucst 27 1 so-2/0/0.0
10.250.1.37/32 intf 0 10.250.1.37 locl 26 1
10.250.1.103/32 dest 0 10.250.1.103 bcst 37 1 ge-7/2/0.0
---(more)---
nancy@sluggo.lab> show route forwarding-table
Internet:
Destination Type RtRef Nexthop Type Index NhRef Netif
10.100.71.0/24 user 0 10.100.67.254 ucst 18 74212 GigE0.0
10.100.71.224/27 user 2 10.100.67.254 ucst 18 74212 GigE0.0
10.250.1.36/30 intf 0 ff.3.0.21 ucst 27 1 so-2/0/0.0
10.250.1.37/32 intf 0 10.250.1.37 locl 26 1
10.250.1.103/32 dest 0 10.250.1.103 bcst 37 1 ge-7/2/0.0
---(more)---
Inc.

Metrics
Possible routing metrics include:
– Hop count
– Composite index/metric
 Bandwidth: Amount of data that can be transmitted in a fixed amount
of time
 Delay: Transit latency of path
Common practice is to link bandwidth as a measure of
cost, like a toll for the router
Path metrics are calculated by adding the interface
metrics along the path
Inc.

Review Questions
1. What functions does a router perform?
2. What functions does a routing algorithm perform?
3. What is the relationship between a routing table and a
forwarding table?
4. What factors affect how a router makes a route
selection?
5. What is a metric and how does a router use metrics to
make routing decisions?
Inc.

Introduction to Juniper Networks Routers
Module 4: M-series and T-series
Product Overview

Module Objectives
 After successfully completing this module, you will be
able to:
– Match Juniper Networks, Inc. products with typical
applications in a service provider network
– Describe the architecture of Juniper Networks M-series and
T-series platforms
– Describe the function of the RE, FPCs, PICs, System, and
Control boards
– Operate the Craft Interface
– Describe packet flow through M-series and T-series platforms
– List three characteristics of JUNOS software
Inc.

Juniper Networks Role in the Internet
 Where we are going…
– Networking hardware evolution
– Juniper Networks: the company
– Juniper Networks M-series and T-series platforms overview
 M5/M10 and the M7i/M10i routers
 M20 router
 M40 router
 M40e router
 M160 router
 T640 Internet routing node
 T320 router
 M320 Router
Inc.

Networking Hardware Evolution
 The first routers were general-purpose computers
– Single CPU, RAM, monolithic operating system
– Low-speed serial interfaces
 Networking advancements:
– More PCs attached to networks
– Increased application bandwidth consumption
– Increased transmission speeds
– Single-CPU router architecture could not keep up!
 Juniper Networks broke tradition with:
– Specialized operating system
 Protected memory, multi-tasking
– Hardware-based packet forwarding
 Juniper Networks M-series and T-series routers implement key
functions on ASICs
 Separation of two equally complex problems—Internet control and
Inc.
high-performance packet forwarding

Juniper Networks: The Company
 Business:
– Converts bandwidth into scalable, differentiable IP services
using a new class of integrated silicon- and software-based
routing systems
 Juniper Networks sells solutions, not just routers
 Mission:
– To be the primary supplier of scalable, reliable,
high-performance IP systems for the new IP infrastructure
Inc.
 Market:
– Supplies systems to numerous worldwide markets that
provide high-speed IP services in both the core and edge
environments

Juniper Networks Product Positioning
PPSSTTNN//
MMoobbiillee M-series/T-series
Platforms
SOHO/ROBO Large Enterprise
Inc.
Small/Medium Enterprise
Education
Service Provider
Consumer Network
Edge: B-RAS
(E-series Routers)
Business Edge
(E-series/M-series
Routers)
RReessiiddeennttiiaall
Core

The E-series Family of Edge Routers
 Series of high-performance broadband remote access
servers (B-RAS)
– The result of Unisphere acquisition in mid-2002
ERX-700
ERX-310
 E-series ERX-1440
edge router operation and configuration is covered
in various E-series router-specific class offerings
– See http://www.juniper.net/training for details
Inc.

M-series and T-series Product Line (1 of 2)
 Family of router platforms that deliver:
– Industry-leading core and dedicated-access platforms
 Solutions that scale in multiple dimensions with market-leading port
density
– Flexible and manageable traffic control
– High reliability features
M40
Router M20
Router
M160
Router
M5/M10
Routers
Forwarding
Performance
per Rack Inch
Copyright © Dec. 2003, 1999 Juniper March 2000
Networks,
Inc.
Sep. 2000
Sep. 1998
. . .

M-series and T-series Product Line (2 of 2)
Common software image/feature set across all platforms!
A Continuing History
of Rapid Innovation
M40e
Router
Inc.
Feb. 2002
Sept. 2003
T640 Internet
Routing Node
T320 Router
August 2002
. . .
Dec. 2001
M7i
M10i

Inc.

M-series and T-series Hardware Overview
– General M-series and T-series platform architecture
– Hardware overview
 Routing Engine
 Packet Forwarding Engine (M-series and T-series)
– The Craft Interface
– Field Replaceable Units (FRUs)
– Summary of platform characteristics
Inc.

Separation of Control and Forwarding
JUNOS
CLI Software
Packet Forwarding Engine
Routing Engine
RT FT
fxp1
FT
Packets In Packets Out
 All M-series and T-series platforms share the same
basic design philosophy
– Clean separation of control and forwarding
 Routing Engine maintains routing table (RT) and
primary copy of forwarding table (FT)
 Packet Forwarding Engine receives FT from Routing
Engine
Inc.

Routing Engine Overview
 JUNOS software resides in flash memory
– Backup copy available on hard drive
 Provides forwarding table to the Packet Forwarding
Engine
– Not directly involved with packet forwarding
– Runs various routing protocols
 Implements CLI
 Manages Packet Forwarding Engine
Inc.

Current Routing Engine Characteristics
RE-333
Processor/clock Pentium III/333 MHz
Memory 768 MB
80 MB
Solid state
flash storage
Hard disk storage 6.4+ GB
PCMCIA
External media flash card/LS-120*
Supported Platforms
Originally shipped
on: M5/10/20/40/40e,
and M160
RE Model
RE-400
Celeron/400 MHz
256, 512, 768 MB
256 MB
(Optional)
20 GB
PCMCIA
flash card
(Optional)
M7i/M10i Only
RE-600
Pentium III/600 MHz
512, 2 GB
128 MB/256 MB
30+ GB
PCMCIA
flash card/LS-120*
All M-series
and T-series except
M7i/M10i
Inc.
Feature
* The M40 router continues to use the original LS-120 drive for external storage regardless of RE model.

Packet Forwarding Engine Overview
 Custom ASICs implement forwarding path
– No process switching
– Value-added services and features implemented in hardware
 Multicast
 CoS/queuing
 Firewall filtering
 Accounting
 Divide-and-conquer architecture
– Each ASIC provides a piece of the forwarding puzzle
Inc.

PFE Components: M-series
 Physical Interface Cards (PICs)
 Flexible PIC Concentrators (FPCs)
 The system midplane
 For M5/M10, M7i/M10i, M20, and M40
– System Control
 M5/M10 and M7i /M10i routers—Forwarding Engine Board/Compact
Forwarding Engine Board, combined FPC and System Control Board
 M20 router—System Switching Board (SSB)
 M40 router—System Control Board (SCB)
 For M40e and M160
– Switching and Forwarding Module (SFM)
– Miscellaneous Control Subsystem (MCS)
– Packet Forwarding Engine Clock Generator
Inc.

PFE Components: T-series
 Physical Interface Cards (PICs)
 T-series FPCs contain one or two PFE complexes
– PFEs interface to other PFEs through the T-series switch
fabric
 Nonblocking crossbar switch matrix with high-speed lines to each FPC
 Switch fabric redundancy
 Switching between PFEs performed by Switch
Interface Boards (SIBs)
– Three SIBs comprise a T320 switch fabric—two active, one
spare
– Five SIBS comprise the T640 switch fabric—four active, one
spare
 The system midplane
Inc.

Physical Interface Cards
 PICs currently support from
0 to 48 physical ports
– Some PICs support
channelized and advanced
CoS options
– IP Service PICs (Tunnel,
Multilink, Monitoring, etc.)
 Services PIC normally have no
physical ports
 Custom ASIC for each
media type
 Status indicators
 Hot-swappable on all
platforms except M20 and
M40 routers
Switch Fabric
Memory
ASIC
Inc.
Physical
Interface
Card (PIC)
PIC
PIC
PIC
FPC

The Flexible PIC Concentrator
 General FPC features
– Supports from 1 to 4 PICs
– Hot-swappable on most platforms
– PowerPC supervisory processor
 Not used for packet forwarding
– From 64 MB to 1.2 GB of memory
 Pooled to create shared memory
switch fabric on M-series platforms
 High aggregate throughput rates*
– M5/M10, M7i/M10i, M20, M40, and
M40e routers: 6.4 Gbps per FPC
– M160 router: 25.6 Gbps per FPC2
– T640 Internet Routing Node: 80+
Gbps with FPC3
– T320 router: 40+ Gbps with FPC3
ASIC
FPC
Inc.
PIC
PIC
PIC
PIC
Switch Fabric
Memory
* The numbers quoted are two times the unidirectional (Simplex) capacity of each
FPC.

M-series System Boards
 General System Board functions:
– Forwarding table updates and route lookups
– Management of ASICs and PFE hardware components
– Environmental monitoring
– Stratum 3 SONET clock generation
– Handling exception/control packets
 Names vary by platform
– M5 and M10—FEB
– M20 and M40—SSB and SCB
– M7i and M10i—CFEB
 Enhanced System Boards feature the second
generation Internet Processor II ASIC
Inc.

Control Boards: M-series and T-series
 General Control Board functions:
– Component power up/down
– Handling hardware faults
– Controlling redundancy
– Environmental monitoring
– Distribution/generation of SONET clocking
 M160/M40e control
– Control provided by Miscellaneous Control Subsystem
(MCS); paired with a Routing Engine to form a Host Module
 Host Module redundancy supported
 T640/T320 control
– Control provided by Control Board (CB); the CB is paired with
a Routing Engine to form a Host Subsystem
 Host Subsystem redundancy supported
Inc.

Internet Processor II ASIC
 The Internet Processor II
– Provides industry-leading performance for longest-match
packet lookup
– Numerous packet processing features:
 Filtering, sampling, logging, counting, and improved load balancing
– Second generation Internet Processor II available on
enhanced system boards
Inc.

System Midplane Examples
 M10 System midplane:
– FEB contains built-in FPCs,
eight PIC slots
 M40e, M160, T640, and T320
System midplane
– Connector Interface Panel
(CIP), eight FPC slots
 M20 System midplane
– System Switching Board
slots, Craft Interface slot, four
FPC slots
0
1
0 1 2 3 4 5 6 7
Connector Interface Panel
Primary SSB
Secondary SSB
Craft Interface
0
1
2
3
Inc.

The Craft Interface
 Craft Interface overview
– LCD display (M40, M40e, M160, T640, and T320 routers only)
– FPC online/offline buttons (M20, M40, M40e, M160, T640,
and T320 platforms)
– PIC online/offline buttons (M5/M10 and M7i/M10i routers)
– Status LEDs
A Typical Craft Interface Panel (T320)
Inc.

Craft Interface Status LEDs
 Status LEDs
Inc.
– OK
 Blinking = starting
 Solid = running
– FAIL
 Solid = taken offline because of failure
 Online/offline buttons
– Press and hold for three seconds to take FPC (or PIC) offline

Alarm Indications
 Red alarm
– Major failure that affects service/safety
 Yellow alarm
– Minor failure that needs attention but does not affect
service
Inc.

LCD Display
 LCD display is available on M40, M160, T640, and T320
platforms only
– Displays general system status when no alarms are present
– Displays alarm information when alarms are present
 Identifies the total number and types of alarms that are active
– Currently, the navigation buttons are only used to obtain the
status of certain PICs
Inc.

Dry Relay Contacts
 Activated with first alarm
– Yellow and red alarms
 Can be disabled with ACO/LT button
on Craft Interface
– New alarms reactivate relay
– Alarm contacts supported on M20, M40,
M40e, M160, and T-series platforms
 Relay contacts located on the Craft
Interface or Connector Interface panel
Inc.

Typical Router Components (T640)
Inc.
Front Back

Product Comparison: M-series
51.2 Gbps
(40 Mpps)
6.4 Gbps
6.4 Gbps
(40 Mpps)
6.4 Gbps
1/4
AC/DC
12.8 Gbps
(40 Mpps)
6.4 Gbps
2/8
AC/DC
51.2 Gbps
(40 Mpps)
6.4 Gbps
8/32
AC/DC
25.6 Gbps
(40 Mpps)
6.4 Gbps
4/16
AC/DC
9.4 Gbps
(8 Mpps)
6.4 Gbps
1/6 (2
built-in
PICs)
AC/DC
12.8 Gbps
(16 Mpps)
6.4 Gbps
2/8
AC/DC
No Yes
Inc.
M160
Router
M40e
Router
M5
Router
M10
Router
M40
Router
M20
Router
M7i
Router
M10i
Router
204 Gbps
(160
Mpps)
25.6 Gbps
8/32
DC Only
2 per rack
8/32
AC/DC
2 per rack
15 per
rack
15 per
rack
2 per rack
5 per rack
21 per
rack
8 per rack
Feature
Chassis
Throughput
(Aggregate)
Slot Throughput
(Aggregate)
Slots/PICs
Power
Units per Rack
Platform
RE/Control
Redundancy
Weight (Max)
No No Yes No Yes Yes
61 Lbs/27.7
Kg
36.5
Lbs/16.6Kg
65 Lbs/29.5
Kg
150
Lbs/68 Kg
280
Lbs/127 Kg
370.5
Lbs/168 Kg
370.5
Lbs/168 Kg
65 Lbs/29.5
Kg
* Numbers quoted are two times the unidirectional (simplex) capacity for each FPC or chassis.

Product Comparison: T-series
Platform
Feature T320
Router
320+ Gbps
(320 Mpps)
FPC3 = 40+
Gbps
FPC 1, 2, and 3
8/16
DC only
3 per
rack
T640 Internet
Routing Node
640+ Gbps (640
Mpps)
FPC3 = 80+
Gbps
FPC 2 and 3
8/32
DC only
2 per
rack
Chassis
Throughput
(Aggregate)
Slot
Throughput
(Aggregate)
Slots/PICS
Power
Units Per Rack
RE/Control
Redundancy Yes Yes
Weight (typical)
565Lbs/256.28Kg
369.9
Lbs/167.78Kg
Inc.
* Numbers quoted are two times the unidirectional (simplex) capacity for each FPC or chassis.

PICs
– Listing of common PICs
– 4-port and 48-port Fast Ethernet, 2-port STM1/OC3c ATM, and
OC-192c
Inc.

Common PICs
Inc.
 Basic
– ATM
– Channelized OC-12, STM1, DS3
– DS-3, 4 port
– T1, E1, T3, E3
– Fast Ethernet
– Gigabit Ethernet, 10 Gigabit Ethernet
– SONET/SDH
 IP Services
– Tunnel Services, Encryption Services, Link Services, Multilink
Services, Monitoring services, and Adaptive Services PIC
(ASP)
 Services (Q Performance Processor)
– Channelized Services (E1, DS3, STM1, and OC12)
– ATM Services (ATM-2)
– Ethernet Services

PIC Examples
4-port Fast Ethernet (M5/M10) 48-port Fast Ethernet (M40e)
Inc.
2-port STM1/OC3 ATM (M20/M40) Quad-wide STM-64/OC192c (M160)

M-series ASICs and Packet Flow
– The M-series Packet Forwarding Engine
 PIC Controller ASIC
 I/O Manager ASIC
 Distributed Buffer Management ASIC
 Internet Processor II
– M-series packet flow
Inc.

M-series ASICs
Internet
Processor II
Forwarding
M-series System Board
(For example, SSB, SFM)
Inc.
Table
Buffer
Manager 1
Buffer
Manager 2
I/O
Manager
I/O
Manager
I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
FPC
PICs
MEM
MEM
MEM
PIC I/O
Manager
PIC I/O
Manager

M-series Packet Flow (1 of 5)
Internet
Processor II
Forwarding
 PIC I/O ASIC
– Connects to FPC I/O ASIC
– Manages physical-layer
framing and bit-stream
signaling
– Detects link-layer errors
(CRC)
– Generates data link-layer
alarms
Packet Forwarding
Engine System
Controller
(SSB, SFM, etc.)
Inc.
Table
Buffer
Manager 1
Buffer
Manager 2
I/O
Manager
I/O
Manager
Key
I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
FPC
PICs
MEM
MEM
MEM
PIC I/O
Manager
PIC I/O
Manager
 – – – – Data
Notification

MEM
Internet
Processor II
Forwarding
System Controller
(For example, SSB and SFM)
 I/O Manager ASIC
– Decodes Layer 2
encapsulation
– Identifies protocol and
checks Layer 3 header
validity
– Classifies traffic for CoS
– Chops incoming packets
into 64-byte
chunks (J-cells)
– Sends J-cells to Buffer
Manager 1 ASIC
– Confirms packet integrity
Inc.
Table
Buffer
Manager 1
Buffer
Manager 2
I/O
Manager
I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
FPC
PICs
MEM
MEM
PIC I/O
Manager
PIC I/O
Manager
 – – – – – – I/O
Manager

MEM
Internet
Processor II
Forwarding
Packet Forwarding
Engine System Controller
I/O
Manager
 Distributed Buffer Manager ASICs
Buffer Key
Manager 2
– Manage packet memory shared across FPC slots
– Extract address information from packets
– Direct FPCs where to forward packets
Inc.
Table
Buffer
Manager 1
I/O
Manager
I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
FPC
PICs
MEM
MEM
PIC I/O
Manager
PIC I/O
Manager
 – – – Data
Notification

Packet Forwarding
Engine System Controller
 Internet Processor II ASIC
– Extracts next-hop
information from system
forwarding table
I/O
Manager
– Passes modified
notification (next-hop
information added) to
Buffer Manager 2 ASIC
– Applies packet filtering
and policy rules
– Collects exception packets
for queuing to Routing
Engine
Inc.
FP
C
MEM
Internet
Processor II
Forwarding
Table
Buffer
Manager 1
Buffer
Manager 2
I/O
Manager
I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
Key
PIC I/O
Manager
PIC I/O
Manager
PICs
MEM
MEM
PIC I/O
Manager
PIC I/O
Manager
 – Extracts next-hop
information from system
forwarding table
– Passes modified
notification (next-hop
information added) to
Buffer Manager 2 ASIC
– Applies packet filtering
and policy rules
– Collects exception packets
for queuing to Routing
Engine
Data
Notification

MEM
Internet
Processor II
Forwarding
 I/O Manager ASIC
Packet Forwarding
Engine System
– Receives 64-byte
chunks from Buffer
Manager 2 ASIC
– Adjusts any required
protocol time-to-live
values
– Encapsulates chunks
inside appropriate
data link layer header
– Sends to PIC I/O
Manager ASIC for
transmission
Controller
(SSB, SFM, etc.)
I/O
Manager
Inc.
Table
Buffer
Manager 1
Buffer
Manager 2
I/O
Manager
I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
PIC I/O
Manager
Key
PIC I/O
Manager
FPC
PICs
MEM
MEM
PIC I/O
Manager
PIC I/O
Manager
 – – – – Data
Notification
PIC I/O
Manager

ASIC Functionality and Packet Flow
– The T-series Packet Forwarding Engine
 PIC Controller ASIC
 Layer 2/Layer 3 Packet Processing ASIC
 Switch Interface ASIC
 Queuing and Memory Interface ASIC
 Internet Processor II
– T-series switch fabric overview
– T-series packet flow
Inc.

T-series Packet Forwarding Engine
Each T-series PFE consists of:
– One or more media-specific PIC ASIC
 Handles physical layer signaling, alarms, and CRC processing
– Layer 2/Layer 3 Packet Processing ASIC
 Provides Link layer encapsulation and decapsulation
 Manages division and reassembly of packets into J-cells
– Queuing and Memory Interface ASICs
 Manage data cell memory buffering
 Manage notification queuing
– Internet Processor II ASIC
 Performs route lookups in forwarding table
– Switch Interface ASICs
 Extract route lookup keys
 Manage cell flow across the switch fabric
Inc.

The T-series Switch Fabric
 Nonblocking topology with any-to-any connectivity
 No single point of failure, all SIBs fully redundant
– Graceful degradation for multiple failures
 T640 switch fabric consists of 5 Switch Interface Boards (SIBs) (5th is a
spare)
 T320 switch fabric consists of 3 Switch Interface Boards (SIBs) (3rd is a
spare)
 Packet order and CoS maintained across fabric
SIB 0
SIB 1
SIB 2
F16
F16
F16
FPC 1
FPC 0
Nf
40Gbps
(FD)
HSLs
Copyright The © T320 2003, Switch Juniper Fabric
Networks,
Inc.

T-series Packet Flow (1 of 10)
Layer2/Layer3
Packet
Processing
ASIC
SONET
or
GigE
PIC
Key
 Packets arrive at an incoming PIC
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
RDRAM
Inc.
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
Packets
in
 Packet
 s
out
   interface
 PIC controller ASIC manages link layer
framing of bit stream
 Detects link layer CRC errors
 Generates link layer alarms
 Passes packets to FPC
RDRAM
Ingress PFE
Data
Notification

Layer2/Layer3
Packet
Processing
ASIC
Key
 Layer 2/Layer 3 Packet Processing
RDRAM
Inc.
SONET
or
GigE
PIC
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
Packets
in
 Packet
s
out
   ASIC parses and validates Layer 2
and Layer 3 headers
 Classifies traffic for CoS processing
 Divides the packets into 64-byte
cells
 Sends cells to Switch Interface ASIC
RDRAM
Ingress PFE Data
Notification

Key
Ingress PFE Data
Notification
Layer2/Layer3
Packet
Processing
ASIC
SONET
or
GigE
PIC
 Switch Interface ASIC extracts the
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
RDRAM
Inc.
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
 Packet
 s
out
 route lookup key
 Key is placed in a notification cell
and passed to the Internet
Processor
 Data cells are sent to the Queuing
and Memory Interface ASICs
RDRAM
Packets
in

Key
Ingress PFE Data
Notification
Layer2/Layer3
Packet
Processing
ASIC
SONET
or
GigE
PIC
 Queuing and Memory Interface
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
RDRAM
Inc.
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
 Packet
s
out
 ASICs pass the data cells to
memory for buffering
 Internet Processor II ASIC performs
the route lookup and forwards the
notification to the Switch Interface
ASIC
RDRAM
Packets
in

Key
Ingress PFE Data
Notification
Layer2/Layer3
Packet
Processing
ASIC
SONET
or
GigE
PIC
 Switch Interface ASIC sends
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
RDRAM
Inc.
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
 Packet
s
out
 bandwidth requests through the
switch fabric to the destination PFE
 Issues read requests to the Queuing
and Memory Interface ASIC to begin
reading data cells out of memory
RDRAM
Packets
in

 Destination Switch Interface ASIC
Layer2/Layer3
Packet
Processing
ASIC
SONET
or
GigE
PIC
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
RDRAM
Inc.
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
  Packet
s
in
Packets
out
sends grants through the switch
fabric
 Originating Switch Interface ASIC
sends a cell through the switch
fabric to the destination PFE
RDRAM
Egress PFE
Switch
Interface
ASIC
Key
Data
Notification

 Switch Interface ASIC extracts the
Layer2/Layer3
Packet
Processing
ASIC
RDRAM
Inc.
SONET
or
GigE
PIC
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
 Packet
 s
in
route lookup key, places it in a
notification, and forwards to the
Internet Processor II
 Internet Processor II performs route
lookup and forwards notification to
Queuing and Memory Interface ASIC
RDRAM
Packets
out
Egress PFE
Switch
Interface
ASIC
Internet
Processor
Key
Data II ASIC
Notification

 Queuing and Memory Interface ASIC
Layer2/Layer3
Packet
Processing
ASIC
SONET
or
GigE
PIC
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Internet
Processor
II ASIC
RDRAM
Switch
Interface
ASIC
Inc.
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Switch
Fabric
Queuing
& Memory
Interface
ASIC
  Packet
s
in
forwards notification to the Switch
Interface ASIC
 Switch Interface ASIC issues read
requests to the Queuing and
Memory Interface ASIC and passes
cells to L2/L3 Processing ASIC
RDRAM
Packets
out
Egress PFE
Queuing
& Memory
Interface
ASIC
Key
Data
Notification

 Layer 2/Layer 3 Packet Processing
ASIC reassembles the data cells into
packets
 Adds Layer 2 encapsulation
Layer2/Layer3
Packet
 Sends the packets Processing
to the outgoing
ASIC
SONET
or
GigE
PIC
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Layer2/Layer3
Packet
Processing
Packet
Processing
ASIC
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
RDRAM
Inc.
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
   Packet
s
in
PIC interface
RDRAM
Packets
out
Egress PFE
Key
Data
Notification

 Egress PIC ASIC adds physical
Layer2/Layer3
Packet
Processing
ASIC
SONET
or
GigE
PIC
Switch
Interface
ASIC
Layer2/Layer3
Packet
Processing
ASIC
Switch
Interface
ASIC
Internet
Processor
II ASIC
RDRAM
Inc.
Switch
Interface
ASIC
Internet
Processor
II ASIC
Switch
Interface
ASIC
Switch
Fabric
Queuing
& Memory
Interface
ASIC
Queuing
& Memory
Interface
ASIC
 Packet
 s
in
layer framing and CRC
 Sends bit stream out to the
network
RDRAM
Packets
out
Egress PFE
SONET
or
GigE
PIC
Key
Data
Notification

Exception Packets
 Exception packets
– Local delivery
– IP options
 Source route, router alert, etc.
– ICMP message generation
 Generally processed by Packet Forwarding Engine
control CPU
– Remaining traffic (local and control) sent to Routing Engine
via internal link
 Rate limiting
 Hardware-based WRR ensures control traffic is not starved
Inc.

JUNOS Software Overview
– Features
– Processes
– Protocol support
Inc.

JUNOS Software Features
 A single image runs on all M-series and T-series
platforms with all features
– Free BSD-based environment
 Fully independent software processes
– Routing, interface control, management, chassis
management, SNMP, CLI, APS, VRRP, sampling, CoS, etc.
– Protected memory environment
 Serious error in one module does not impact other modules or packet
forwarding
 Automatic core dumps for serious faults
 Purpose built for performance and stability in the
Internet core
Inc.

JUNOS Software Processes
User
JUNOS Internet Software
Routing
Engine
Routing
Tables
Routing
Protocol
Process
SNMP
Interface
Process
Command-Line
Interface (CLI)
Chassis
Process
Forwarding
Table Kernel
Forwarding
Table
Interface
Process
Chassis
Process
Distributed
ASICs
Microkernel
Embedded Microkernel
Packet
Forwarding
Engine
Inc.

The Kernel
 The kernel
– Provides the underlying infrastructure for all the JUNOS
software processes
 Provides the link between the routing tables and the RE's forwarding
table
 Responsible for all communication with the PFE, including keeping the
PFE’s copy of the forwarding table synchronized
Routing
Protocol
Process
Interface
Process
Command-
Line
Interface (CLI)
Chassis
Process
Forwarding
Table Kernel
Inc.

Routing Protocol Process
 Core functions
– Controls routing protocols running on router
– Starts all configured protocols
– Handles all routing messages
– Maintains routing tables
– Implements routing policy
Routing
Tables
Routing
Protocol
Process
(rpd)
JUNOS Kernel
Inc.

Industrial-Strength Protocols
 Unicast routing protocols
– Intermediate System-to-Intermediate System (IS-IS)
– Open Shortest Path First (OSPF and OSPF3)
– Routing Information Protocol (RIP and RIPng)
– Border Gateway Protocol (BGP)
 Multicast routing protocols
– Distance Vector Multicast Routing Protocol (DVMRP)
– Protocol Independent Multicast (PIM)
– Multicast Source Discovery Protocol (MSDP)
– Internet Group Management Protocol (IGMP and MLD)
– Session Announcement Protocol and Session Description
Protocol (SAP/SDP)
 MPLS application protocols
– Multiprotocol Label Switching (MPLS)
 Provider-provisioned VPN support (Layer 2 and 3)
– Resource Reservation Protocol (RSVP)
– Label Distribution Protocol (LDP)
Inc.

Review Questions
1. Which Juniper Networks M-series or T-series
routers are aimed at the Internet core? What
about the edge?
2. What are the primary responsibilities of the
Routing Engine and the Packet Forwarding
Engine?
3. What is the purpose of and relationship between
FPCs and PICs?
4. What is the purpose of the Craft Interface?
5. Describe packet flow through Juniper Networks
M-series and T-series platforms
6. Which software process maintains the routing
tables and implements routing policy?
Inc.

Juniper Networks
Module 5: Installation and
Initial Configuration

Module Objectives
After completing this module, you should be able to
describe
– Important installation issues
– Initial configuration process
– Software installation from scratch
– Software component upgrades
– How to back up existing router software
Inc.

Chassis Installation
 M40/M160 Craft interface displays
– Typical M160 weighs 300 pounds (135 kg)
– Lifting requires three or more people
 Remove heaviest components first
– Power supplies
– FPCs
– Fan Trays
 Lift into rack
– Do not lift M40 by Routing Engine handles
 Replace components
Inc.

Power Up and Power Down
 Powerup
– Perform more checks
– Connect all cables
– Turn on one power supply
– Turn on second power supply
 Powerdown
– Shutdown Junos Routing software
– CLI request system halt command
– Turn off Power Supplies
Inc.

Visible Activity at Startup
 M40/M160 Craft interface displays
– Starting Routing Engine
– Starting PFE
– Starting cards
 FPC LED
– Blink green while testing
– Become solid green when tests pass
 Alarm LEDs light as needed
Inc.

 Using serial console
– Root password
– Machine name
– IP address (prefix) and prefix length assigned to
management interface (fxp0)
– Default router
– DNS server
Inc.

Troubleshooting
 Craft interface
– Red LEDs indicate failure
– M40/M160 LCD displays all major and minor alarms
 Syslog messages
– Contain more detailed information
– CLI show log messages command
Inc.
 CLI
– Interactive failure analysis using show commands
– monitor log files using monitor command

Boot Devices and Media
 Removable media
– Used for install and upgrade, normally left empty
– M40—120-MB high-capacity floppy drive
– M20/M160—110-MB PCMCIA flash card
 Flash drive
– Solid-state nonrotating media
– Primary source for booting software
 Hard drive
– Traditional rotating media
– Secondary source for booting software
Inc.

Software Installation
 Arrives preinstalled from factory onto
– Flash drive
– Hard drive (alternate copy)
– Removable LS-120 floppy or PCMCIA flash card (use as a last resort)
 Can boot from alternate copy
– If flash drive fails, router can still boot from hard drive or removable
media
 Upgradable
– Upgrade packages available through the Internet or on removable
media
Inc.

Boot Sequence
 Hardware controlled
– Software notifies hardware when boot completes
Removable
media Halt
Success? Success? Success?
Inc.
Done
Solid-state
flash disk
Rotating
disk
Done Done

Root password
– Root password not set at factory
– Must use console to configure root password
Router and domain name
Management interface IP address and prefix length
Default router IP address
DNS server IP address
Inc.

Enter configuration mode
root@> configure
[edit]
root@#
Set root password
– Plain text known
root@# set system root-authentication
plain-text-password
– Pre-encrypted password
encrypted-password encrypted-password
– SSH (secure shell) key
ssh-rsa key
Inc.

Set router name
[edit]
root@# set system host-name lab2
Set router domain name
[edit]
root@# set system domain-name juniper.net
Commit changes so far
[edit]
root@# commit
commit complete
[edit]
root@lab2#
Inc.

Set management Ethernet IP address and prefix
[edit]
root@lab2# set interfaces fxp0 unit 0 family inet address ip-address/
prefix-length
Set default route
[edit]
root@lab2# set system backup-router gateway-address
root@lab2# set routing-options static route default nexthop gateway-address
retain no-readvertise
Set name server address
[edit]
root@lab2# set system name-server ns-address
Inc.

Full Installation
Reinstall JUNOS software if storage media fails or is
corrupted
Future major software revisions may require full
installation
Three steps
– Prepare to reinstall JUNOS software
– Reinstall JUNOS software
– Configure JUNOS software
Inc.

Full Installation: Preparation
 Record basic information
– Router name
– Management interface IP address and prefix length
– Default router IP address
– Domain name and DNS server IP address
 Copy existing configuration file to a safe place on the network
– Located in /config/juniper.conf
– Full installation erases both flash and rotating drives
 Locate your Juniper installation media
– LS-120 floppy or PCMCIA card contains entire JUNOS distribution
Inc.

Full Installation: Reinstallation
 Insert installation media into Routing Engine
– M40—LS-120 floppy
– All others—PCMCIA flash card
 Reboot router
– Use the CLI from the serial console
root@lab2> request system halt
– Power-cycle router
 Follow prompts
– Enter configuration information saved during installation preparation
 System reboots automatically after installation completes
Inc.

Software Configuration
Log in as root
no-name (ttyd0)
login: root
Last login: date on ttyd0
Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994
The Regents of the University of California. All rights reserved.
---JUNOS 4.1R1 built 2000-07-24 09:29:44 UTC
#
Start CLI
# cli
root@no-name>
Inc.

Software Configuration
Enter configuration mode
root@no-name> configure
[edit]
root@no-name#
Set root password
– Plain-text
root@no-name# set system root-authentication
plain-text-password text-password
– Pre-encrypted password
encrypted-password encrypted-password
– SSH key
ssh-rsa key
Inc.

Software Update Packages
JUNOS software updates are contained in four
packages
– jkernel–Operating system
– jroute–Routing Engine software
– jpfe–Packet Forwarding Engine software
– jdocs–On-line documentation
– jbundle–All four upgrade packages combined
– jinstall-Upgrade to/from 5.0
Packages can be upgraded individually
CLI show system software command displays
installed packages
Inc.

Jinstall vs. Jbundle
When to use jinstall
– Upgrade 4.x to 5.y
– Downgrade 5.y to 4.x
When to use jbundle
– 4.x to 4.y transition
– 5.x to 5.y transition
Inc.

Package Naming Convention
Software packages have standard names
package-m.nZnumber.tgz
– m.n is the major version number
– Z is a single uppercase letter
 A–Alpha
 B–Beta
 R–Release
 I–Internal
– number is the release number, which might include the build
number for that release
For example
jbundle-4.1R1.2.tgz
Inc.

Back Up Existing Software
System software and configuration can be backed up
to rotating disk
Best used
– Before major upgrade to ensure system recovery if necessary
– When system is judged to be stable
CLI request system snapshot command
Inc.

Upgrade Software Jbundle
 Download current package from software download page at
www.juniper.net
 Add new package
root@lab2> request system software add new-package-name
Checking available free disk space...11200k available,
6076k suggested.
 Reboot router
root@lab2> request system reboot
Inc.

Upgrade Software jinstall
Prep the machine:
– cli> file copy jinstall-url /var/tmp/jinstall-pkg
– Copy customer configs and other files/executables
– Do not worry about JUNOS configs, uncommitted config, log
files, SSH keys
Inc.

How to use jinstall
 Add jinstall
– cli> request system software add /var/tmp/ jinstall-pkg
Installing package '/var/tmp/jinstall-package name'...
WARNING: This package will load JUNOS software release-number.
WARNING: It will save JUNOS configuration files, log files, and SSH keys
WARNING: (if configured), but erase all other files and information
WARNING: stored on this machine. This is the pre-installation stage
WARNING: and all the software is loaded when you reboot the system.
WARNING: If you do not wish to proceed, you will be able to abort the
WARNING: installation.
Saving the config files ...
Installing the bootstrap installer ...
Inc.

How to use jinstall
Type yes to reboot:
WARNING: A reboot is required to load this software correctly. If you
WARNING: wish to abort the installation, enter 'no' below.
Reboot the system (yes/no) [no] ? yes
Shutting down in 10 seconds ...
Saving package file in /var/sw/pkg/jinstall-packagename ...
Saving state for rollback ...
*** FINAL System shutdown message from user@host ***
System going down IMMEDIATELY
Shutdown NOW!
Go for a coffee. Router will be up in 5-7 min.
Inc.

Cautions
5.0 will reformat the disk. Customer configs and other
files/executables will be lost.
Connect to the router via the management ethernet
If the juniper.conf has statements not supported in the
new release, then mgd may fail during commit
Inc.

Jinstall internal mechanics
Preinstall phase does various checks. Stores preinstall
information in /var/tmp/preinstall
Reboot to come up on the installer:
– Perform more checks
– Reformat the disk
– Lay a base OS (files that are needed but not in jbundle)
– Lay the jbundle
Second reboot to come up on the new JUNOS
Inc.

End of Life Procedures
 Hardware EOL
– Notifcation 180 day in Advance
– During notification period can continue to purchase
– Repaired or Replaced upto 3 years after EOL date
 Software EOL
– Software Support covers most recent release and two
previous (e.g. 4.3, 4.2, 4.1)
– New Releases schedule for FRS every 3 months
– Major Release – 6 month notice of EOL
Inc.

Review Questions
1. What JUNOS boot Sequence?
2. What are the JUNOS software update Packages?
3. Describe the Package naming convention.
4. Explain the difference between Jbundle and Jinstall.
Inc.

Juniper Networks
Module 6: JUNOS Configuration Basics

Module Objectives
be able to:
– Explain how to gain access to a Juniper router
– Describe the difference between the CLI command mode and
configuration mode
– Describe how to navigate and modify the Candidate
configuration
– Describe how to change the Active configuration
– Explain the method used to describe a customer interface
– Describe how to configure the physical and logical properties
of an interface on a Juniper router
Inc.

Access to Router
Console
Management port, using Telnet, ssh, RADIUS
Inc.
NC
C
NO
NC
C
NO
ACO/LT AUX/MODEM MGMT CONSOLE
OFFLINE ONLINE MASTER
OFFLINE ONLINE MASTER
RE0
RE1
FPC0
FPC1
FPC2
FPC3
FAIL OK
FAIL OK
FAIL OK
FAIL OK

User Authentication
Name and password
Individual accounts
Per-user command "class" permissions
lab2 (ttyd0)
login: nigel
Password:
Inc.

Features
Line editing
Command history
Command completion
Context-sensitive help
Inc.

CLI Modes
Operational mode
nigel@lab2>
– Monitor and troubleshoot the software, the network
connectivity, and the router
Configuration mode
nigel@lab2#
– Configure the router, including interfaces, general routing
information, routing protocols, user access, and system
hardware properties
Inc.

CLI Commands
Command hierarchy
brief
exact
protocol
table
terse
bgp
chassis
interfaces
isis
ospf
route
version
clear
configure
monitor
set
show
Inc.

Logging In
lab2 (ttyd0)
login: nigel
Password:
Last login: Fri Feb 18 19:23:16 on ttyd0
Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994
The Regents of the University of California.
---JUNOS 4.1R1 built 2000-07-24 09:29:44 UTC
nigel@lab2>
Inc.

Help
Type ‘?’ anywhere on command line
lab@omaha> ?
Possible completions:
clear Clear information in the system
configure Manipulate software configuration information
file Perform file operations
help Provide help information
…
lab@omaha> show ?
aps Show APS information
arp Show system ARP table entries
as-path Show table of known AS paths
…
Inc.

Editing Command Lines
lab@omaha> show interfaces
Ctrl-b
Ctrl-a
Ctrl-f
Ctrl-e
Inc.

Command Completion
<space> completes a command
root@lab2> sh<space>ow i<space>
'i' is ambiguous.
igmp Show information about IGMP
interfaces Show interface information
isis Show information about IS-IS
root@lab2> show i
Inc.

Software Configuration Overview
Create a hierarchy of configuration statements
– Enter commands in CLI configuration mode
root@lab2# set chassis alarm sonet lol red
– ASCII text file and display
chassis {
alarm {
sonet {
lol red;
}
Inc.
}
}

Activating a Configuration
commit
rollback n
Candidate
Configuration
Active
Configuration
0
1 2 ...
Rollback files stored in
/config/juniper.conf.n (n=1-3)
/var/db/config/juniper.conf.n (n=4-9)
Inc.

Statement Hierarchy
firewall interfaces protocols system more…
clock fpc
chassis
atm e3 ethernet
sonet t3
Inc.
alarm
Less Specific
More Specific
top

Entering Configuration Mode
Type configure or edit at the CLI
operational mode prompt
root@lab2> configure
Entering configuration mode
[edit]
root@lab2#
Inc.

Moving Between Levels
Moving between levels of the statement hierarchy
[edit]
user@host# edit chassis alarm ethernet
[edit chassis alarm ethernet]
top
clock fpc
chassis
alarm
atm e3 ethernet
sonet t3
Inc.

Moving Between Levels
user@host# up
[edit chassis alarm]
user@host# top
[edit]
top
clock fpc
chassis
alarm
atm e3 ethernet
sonet t3
Inc.
top
up

Displaying Current Configuration
[edit]
user@host# show chassis alarm
sonet {
lol red;
pll yellow;
Inc.
}
[edit]
user@host# edit chassis alarm
user@host# show
sonet {
lol red;
pll yellow;
}

Exiting Configuration Mode
exit from top level
exit configuration-mode from any level
Operational
exit configuration-mode
top
exit/up
Inc.
mode
[edit]
[edit chassis]
[edit chassis
alarm]
exit
edit/configure
edit chassis
edit alarm

Standard Interfaces
 Interface contained on
PIC
 PIC plugs into FPC
– FPC has room for four
PICs
 FPC plugs into chassis
PPhhyyssiiccaall
IInntteerrffaaccee
CCaarrdd
PPIICC
Inc.
PPIICC
PPIICC
FPC

Standard Interfaces
System uses consistent names for all customer
interfaces
Based on
– Interface port type
– FPC slot number
– PIC slot number within FPC
– Port number within PIC
Inc.

Interface Port Type
at— ATM over SONET/SDH ports
e1— E1 ports
e3— E3 ports
fe— Fast Ethernet ports
so— SONET/SDH ports
t1— T1 ports
t3— DS-3 ports
ge— Gigabit Ethernet ports
ae- Bundled Ethernet ports
Inc.

FPC Slot Numbers
0 1 2 3 4 5 6 7 M160 0 1 2 3 4 5 6 7
M20 0
1
1
2
Inc.
M40
3
0 M10

PIC Slot Numbers
0
1
2
3
M40 and M160
– Top to bottom
All others
– Right to left
3 2 1 0
Inc.

Port Numbers
0
1
2
3
 M40 and M160
 Top to bottom
 Right to left
 All others
3 2
 Right to left
 Bottom to top 1 0
Inc.

Interface Names
Physical interfaces have
standard names
– Type
– FPC slot
– PIC slot
– Port number
so-5/2/3
Inc.

Typical FPC and PIC Placement
 Transient interfaces
identified according to
FPC/PIC/port convention
 FPC and PIC numbering
varies by platform
– M40/M160 platforms support
eight FPCs, numbered from
left to right
 PICs numbered from top to
bottom (0–3)
– M20 platform supports four
FPCs numbered from top to
bottom
 PICs numbered from right to
left (0–3)
FPCs 0–7
(Left to right)
 FPC slot and PIC port
numbers are labeled!
Typical FPC and PIC Numbering
(T640)
PICs 0–3
(Top to bottom)
Inc.

Interface Names
Logical interfaces are used to set up Frame
Relay DLCIs or ATM virtual circuits
so-5/2/3.43
Interface number is separate in meaning from
the actual DLCI or ATM VC and can be any
arbitrary value
Suggested convention is to keep them the
same whenever possible
Inc.

Permanent Interfaces
Router has two permanent interfaces
– Out-of-band management interface is called fxp0
– Internal Routing Engine to PFE connection is called fxp1
Inc.

Configure Interfaces
Inc.

Two steps
– Configure physical properties
– Configure logical properties
Inc.

– Physical properties
 Clocking
 Scrambling
 Frame check sequence (FCS)
 Maximum transmission unit (MTU)
 Keepalives
 Other link characteristics
– Logical properties
 Protocol family (Internet, ISO, MPLS)
 Addresses (IP address, ISO NET address)
 Virtual circuits (VCI/VPI, DLCI)
 Other characteristics
Inc.

 Standard configuration statement hierarchy
interfaces {
interface-name {
physical-properties;
[…]
unit unit-number {
logical-properties;
[…]
}
Inc.
}
}

Configure Physical Properties
Configure physical properties of the interface using the
set command:
set interface so-1/0/3 no-keepalives
Or park yourself in the interfaces section of the
hierarchy and set many options
lab@omaha> configure
[edit]
lab@omaha# edit interfaces so-1/0/3
[edit interfaces so-1/0/3]
lab@omaha# set no-keepalives
lab@omaha# set sonet-options fcs 32
lab@omaha# commit
Inc.

Default Settings
Default settings for an interface are usually enough to
get you talking
Most interfaces do not need complex setup
Inc.

Logical Interface Settings
 Each physical interface has one or more logical interfaces
 Logical interface separates configuration information for each
ATM virtual circuit, Frame Relay DLCI, or VLAN
 Some physical interface encapsulations allow only one possible
logical interface
Inc.
– PPP
– HDLC

Logical Interface Settings
Logical settings
– Protocol family (Internet, ISO, MPLS)
 Protocol MTU
 IP address
 Other protocol options
– Virtual circuit identifiers (VPI.VCI, DLCI)
– Other according to-circuit characteristics
Inc.

Unit Numbers
 Each logical interface has a unit number
 Number can be arbitrary
– Typically, the unit number is the same as the VC or DLCI number
 Some physical interfaces have only one possible logical interface,
and one unit number only, which must be configured as unit zero
Inc.

Configure Logical Interfaces
Use the set command to configure a logical interface,
using the unit number
For example
set interface so-1/0/3 unit 40 dlci 40
Or park yourself at the unit level
[edit]
lab@omaha# edit interfaces so-1/0/3 unit 40
[edit interfaces so-1/0/3 unit 40]
lab@omaha# set dlci 40
lab@omaha# set family inet address 10.0.20.1/24
lab@omaha# commit
Inc.

Configure Protocol Families
Each major protocol is called a family
Internet protocol has TCP, UDP, and ICMP as family
members
Most common protocol families are
– Internet (inet)
– International Standards Organization (iso)
– Traffic engineering (mpls)
– Multiple families can live on one logical interface
Inc.

 Internet protocol family (inet)
 Allows you to set
– IP address: address A.B.C.D/prefix_length
– Remote address on point-to-point links: destination A.B.C.D
– Broadcast address: broadcast A.B.C.D
– MTU size: mtu bytes
– ICMP redirect control: no-redirects
Inc.

 Minimal sample configuration
[edit]
lab@omaha# edit interfaces so-1/0/3
[edit interfaces so-1/0/3]
lab@omaha# set unit 0 family inet address 10.0.20.1/24
lab@omaha# commit
 Displayed as
interfaces {
so-1/0/3 {
unit 0 {
family inet {
address 10.0.20.1/24;
}
Inc.
}
}
}

Review Questions
1. What are the two types of CLI modes?
2. What are the interface types and names?
3. What are the two permanent interfaces?
4. What are the two basic interface characteristics?
5. What are some examples of physical interface settings?
6. What are some examples of logical interface settings?
Inc.

Lab 2: CLI Configuration
Lab objective:
Introduction to Juniper CLI
Inc.

Juniper Networks
Module 7: Routing Protocol Basics

Module Objectives
be able to:
– Explain the difference between static routing and dynamic
routing, and explain when to use each type of routing
– Describe the characteristics and operation of distance vector
and link-state routing protocols
– Explain how network convergence occurs and provide real-life
examples
– Explain how routes are selected on a routed network and
routing metrics
– Explain the role of interior gateway protocols and exterior
gateway protocols, including Border Gateway Protocol (BGP)
– Explain how JUNOS software implements routing tables and
routing policy
Inc.

Types of Routes
Inc.
Static
– All packets forwarded to predetermined destinations defined
by an administrator
Dynamic
– Packets are forwarded to dynamically calculated routes
determined by a routing protocol

Static Routing
Inc.
Benefits
– Good for small networks
– Can help create a secure network
– Efficiently uses router resources
Drawbacks
– Does not handle network failures well
– Does not scale well

Static Routing Example
Destination Next Hop
10 Direct
172.16 Router B
192.168.5 Router C
192.168.6 Router C Destination Next Hop
10 Router A
172.16 Router B
192.168.5 Direct
192.168.6 Router D
Network
192.168.5
Router B Router C
Network
172.16
Network
10
Router A
Inc.
Network 192.168.6
10 Router A
172.16 Direct
192.168.5 Router C
192.168.6 Router C
192.168.6 Direct
Default Router C
Router D

Static Routing with Link Failure
Network
192.168.5
Router B Router C
Network
172.16
Network
10
Router A
Network 192.168.6
Inc.
10 Direct
172.16 Router B
192.168.5 Router C
192.168.6 Router C
10 Unreachable
172.16 Router B
192.168.5 Direct
192.168.6 Router D
10 Router A
172.16 Direct
192.168.5 Router C
192.168.6 Router C
192.168.6 Direct
Default Router C
Router D

Floating Static Routes
Static routes CAN
handle link failures!
A floating static route is
a backup static route
that is less preferred
than more direct routes
(static or dynamic)
Floating static route is
used only when the
preferred route is
unavailable
Use with caution!
Router A Router B
Network X Router C
Network X Router B
Router C
Network X
Inc.
Network X Router C
Network X Router A

Dynamic Routing
Communicate
what?
Between
whom?
Routing tables Neighbors
Interface status All routers
Distance-Vector
Link-State
Inc.

Routing Protocol Convergence
 Convergence: when all routers in a given routing domain achieve
a consistent view of that routing domain
 Routing protocols must achieve convergence in order to route
packets consistently from one location to another
Inc.

Interior and Exterior Gateway Protocols
Interior Gateway Protocols (IGPs)
– Routing protocols that run within an autonomous system (AS)
to exchange network reachability information
Exterior Gateway Protocols (EGPs)
– Routing protocols that exchange routing information between
autonomous systems
AS 1 AS 2
IGP EGP IGP
• Border
Gateway
Protocol
IGPs
• RIP
• OSPF
• IS-IS
Inc.

Distance Vector Protocols
Distance vector neighbors exchange vectors
– Metric is typically hop count
– Vectors reflect both distance and direction
– Vectors are stored in the routing table
– Entire table or a portion of table is sent
The longest network path is limited
Each router sends a routing table update periodically
Inc.

When to Use Distance Vector Routing
Use in very small networks that have few, if any,
redundant paths and no stringent network performance
requirements
Epitome of the distance-vector routing protocol is
Routing Information Protocol (RIP)
Distance vector drawbacks:
– Long convergence time
– Simplistic metrics
Inc.

Distance Vector Stability Issues
Counting to infinity
Routing loops Network A
Network A = 1 hop
Network A = 2 hops
3
R1 R2
R3
Inc.
4
5
6
…

Link-State Routing Protocols
Link-state routing protocols build and maintain a
database of link state information
Hello messages are used to discover neighbors
Costs are associated with links
Updates are sent to communicate link state changes
Information is flooded to all neighbors who create a
link state database
Inc.

The Link-State Database (LSDB)
The LSDB is like a puzzle that, when complete, is an
accurate picture of the network
LSDB entries are like puzzle pieces that can describe:
– Routers and their attached links
– Links and their attached routers
– Routing information from outside the network
– Link metrics, often represented as Cost
Each router maintains its own copy of the LSDB
Each router stores a copy of every LSDB entry in the
network
Different protocols use different names for LSDB
entries
– More on that later…
Inc.

When to Use Link-State Routing
Use link-state routing with:
– Any size, well-designed network
– Any network that requires network scalability
– Larger, more complicated networks
– Faster convergence required
Drawbacks
– Can flood the network's transmission facilities, thereby
significantly decreasing the network's capability to
transport data
– Memory and processor intensive
Inc.

Martian Addresses
Host or network addresses about which all routing
information is ignored
Commonly sent by improperly configured systems on
the network and have destination addresses that are
obviously invalid
In IPv4, these are the default martian addresses:
– 0.0.0.0/8
– 127.0.0.0/8
– 128.0.0.0/16
– 191.255.0.0/16
– 192.0.0.0/24
– 223.255.255.0/24
– 240.0.0.0/4
Inc.

Route Flapping
What is route flapping?
– Instability in the reachability of a prefix
– Occurs during a topology change
– In an unstable network, routers might be unable to decide on
a route to a destination
Dealing with route flapping
– Different protocols have different solutions
Inc.

JUNOS Routing Policy
Controls routing information transferred between
routing table and each routing protocol
– Incoming routing information can be ignored or changed
– Outgoing routing information can be suppressed or changed
Some match conditions are protocol-specific
Inc.

When to Apply Policy
You do not want to import all learned routes into the
routing table
You do not want to advertise all learned routes to
neighboring routers
You want one protocol to receive routes from another
protocol
You want to modify information associated with a route
Inc.

Import and Export
 Policy filtering is done with respect to the JUNOS
routing table
 Export policy is applied to active paths in the routing
table
Inc.
NNeeiigghhbboorrss
PPrroottooccooll
Routing
table
Forwarding
table
PPrroottooccooll
Import
Routes Routes
PFE
Export
NNeeiigghhbboorrss

Routing Policy
 Allows you to filter and control routing information
entering and leaving the router
 Separate policy for each routing protocol
Routes Routes
Inc.
NNeeiigghhbboorrss
PPrroottooccooll
Routing
table
Forwarding
table
PPrroottooccooll
PFE
NNeeiigghhbboorrss
Import policy #1
Import policy #2
Export policy #1
Export policy #2

Routing Policy
Policies can be chained together to increase their
effectiveness
Route PPoolliiccyy
Accept
PPoolliiccyy
Reject
Accept
... Reject
Last
policy
Accept
Default
policy
Reject
Inc.
Accept
Reject

Routing Policy
Policies contain collections of terms
Terms contain a condition and an action to apply to
each route
Route TTeerrmm
Accept
TTeerrmm
Reject
Accept
... Reject
Last
term
Accept
Inc.
Next
policy
Reject

Default Routing Policy Actions
Different default policies for each protocol being
imported or exported describe default protocol
behavior
Reaching the end of a policy, or chain of policies,
invokes default policy for that protocol
Inc.

How Routing Policies Are Evaluated
RRoouuttee PPoolliiccyy
Accept
Reject
PPoolliiccyy
Accept
Reject
Last
Configured
policy
Accept
Inc.
Default
policy
action
Reject
Accept
Reject
Continue
evaluating
Continue
evaluating
until…

Routing Policy Example
Additional
Policies
Inc.
RRoouuttee
TTeerrmm
Accept
or reject
TTeerrmm
TTeerrmm
Accept
or reject
Accept
or reject
Policy 1
TTeerrmm
Accept
or reject
TTeerrmm
TTeerrmm
Accept
or reject
Accept
or reject
Policy 2
TTeerrmm
Accept
or reject
Default
action

Routing Policy Example
RRoouuttee
Policy term
Source
Conditions
Destination
Conditions
Match
AAccttiioonnss
Does not
match all
conditions
Default
action
Inc.

JUNOS Routing Databases
Routing table
Master forwarding table
Forwarding table
Network interfaces
Routing Engine
Routing
Protocol Process
JUNOS kernel
Inc.

Review Questions
1. When would you implement static routing? Dynamic
routing?
2. What are the primary differences between distance-vector
protocols and link-state protocols?
3. How does a distance-vector protocol handle router
updates?
4. What happens when the network converges?
(Describe the process.)
5. Describe the JUNOS routing policy and its
implementation.
Inc.

Lab 3: Static Routing
Inc.

Juniper Networks
Module 8: Interior Gateway Protocols

Module Objectives
 After successfully completing this module, you should be able to:
– Describe RIP architectural features, standards, limitations, and
packet format
– Explain JUNOS support for RIP
– Configure a Juniper Networks router with a minimum RIP
configuration
– Describe OSPF standards, terminology, routing algorithms, packet
format, external metrics, designated routers, and traffic engineering
extensions
– Explain JUNOS software support for OSPF
– Configure a Juniper Networks router with a minimum OSPF
configuration
– Describe IS-IS standards, terminology, network addressing, packet
format, and traffic engineering extensions
– Explain JUNOS software support for IS-IS
– Configure a Juniper Networks router with a minimum ISIS
configuration
Inc.

IGP’s vs EGP’s
IGP – Internal Gateway Protocol
– Used to optimize the route a packet takes between points
within an Autonomous System(AS – network infrastructure
under a unique set of administrative and technical policies)
EGP – External Gateway Protocol
– Used to provide for the exchange of routing information
between Autonomous Systems
– Typically designed for doing policy routing, providing control
over routes leaving and entering an AS
Inc.

What Is OSPF?
An interior gateway protocol (IGP) based on the
shortest path first (SPF) algorithm, also known as the
Dijkstra algorithm
Created to fill the need for a high-functionality,
standards-based IGP for the TCP/IP protocol family
Main RFCs:
– 1587 – OSPF NSSA Option
– 2328 – OSPF Version 2 (current implementation)
Inc.

What Is a Link-State Protocol ?
Link = router interface
State = description of interface and its relationship to
neighboring routers
OSPF routers send link-state advertisements (LSAs) to
all other routers within the same hierarchical area
Routers store information in a link-state, or topological,
database
Each OSPF router uses the SPF algorithm to calculate
the shortest path to each node
Inc.

What Is SPF?
Places each router at the root of a tree and calculates
the shortest path to each destination based on the
cumulative cost to reach that destination
Each router has its own view of the topology, even
though all the routers build a shortest-path tree using
the same link-state database
Inc.

OSPF Routing Hierarchy
Largest entity is the autonomous system (AS)
An AS can be divided into areas, groups of contiguous
networks, and hosts
– Routers within a single area have identical link-state
databases
– Area Border Routers (ABRs): routers with interfaces in
multiple areas
– AS Boundary Routers (ASBRs): routers that act as gateways
to other protocols or another AS
Inc.

OSPF Backbone
OSPF backbone (Area 0) distributes routing
information between areas
– Contains all area border routers and backbone routers
– All traffic between areas goes through the backbone
Backbone is itself an OSPF area
If backbone is configured as not contiguous, must
configure virtual links
– Between any backbone routers that share a link to a
nonbackbone area, or the transit area
– Function as direct links
Inc.

OSPF Area Relationships
Intra-area routes
Backbone
Area 1
Area 3
Area 2
(0.0.0.0)
Inter-area routes
(Summary routes)
Inc.
RIP
External routes BGP

OSPF Stub Areas
Stub areas
– Do not carry external routes
– Virtual links cannot be configured across
– Cannot contain ASBR
Totally stubby areas
– Stub area that only receives the default route from the
backbone
Not-so-stubby areas
– Allows limited importing of external routes
Transit areas
– Used to pass traffic from one adjacent area to the backbone,
or to another area if the backbone is more than two hops away
from an area
Inc.

OSPF Area Types
Inter-area routes
(summary routes) Default route
Backbone
Stub
area
(0.0.0.0)
Inc.
RIP
External routes BGP
Totally stubby
area
Not-so-stubby
area
Intra-area routes

OSPF Neighbors
Routers that share a common segment within a single
area are neighbors
Neighbors become adjacent to exchange LSAs
The goal: to achieve identical link-state databases
Inc.

Neighbors Exchange Link-State Info
Neighbors exchange link-state update packets
containing LSAs at initialization and when routing
information changes
Link-states exchanged by flooding: Each router that
receives a link-state update stores a copy in its link-state
database and then propagates the update to other
routers
Once the database is complete, the router calculates an
SPF Tree to all destinations using the Dijkstra
algorithm
OSPF activity determined by the amount of change –
the less change, the less activity
Inc.

Junos routing overview from Juniper

Junos routing overview from Juniper

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