Redundant Internet service provision - customer viewpoint

Redundant Internet service provision -
customer viewpoint

Kae Hsu
kae@du.net.tw
Communication Network Dept.

Agenda
http://www.seed.net.tw

 Requirement of redundant
 Types of redundant
 Backup
 Load-sharing
 Multihoming
 Challenge to service provider
 Solution for consumers
 Another redundant issue – MPLS VPN
 Next challenge

2 2006/09/07

Agenda

 Backup
 Load-sharing
 Multihoming
 Next challenge

3 2006/09/07

Requirement of redundant

 Internet access is a very important service
today for:
 Enterprise/business
 Tools of operation
 Decreasing the cost
 Increasing the revenue
 Consumers
 Communication tools
 Entertainment
 Customers need redundant service provision

4 2006/09/07


 It was expensive to build a redundant
Internet topology for end-user before:
 Use leased line/ISDN for backup only
 Less circuit utilization
 Expensive network equipments
 Complex network operation

5 2006/09/07


 Today, new type of circuit provides simple
and convenient way to build a redundant
Internet access service
 FTTx
 xDSL
 Wireless
 More and more cheap and efficient network
equipments appear
 SP could provide enough redundant service
for customer requirements

6 2006/09/07

Agenda

 Backup
 Load-sharing
 Multihoming
 Next challenge

7 2006/09/07

Types of redundant

 3 types of redundant (1)
 Backup
 Redundant circuit
 Primary: expensive, better quality
 Backup: cheap, less bandwidth
 Use backup circuit only when primary circuit is
failure

8 2006/09/07

Types of redundant - Backup

 Traditional circuit backup topology
Leased Line
PE
ISP
CE
ISDN
PE User

ISP
PE X
Leased Line

CE
ISDN
PE User

 Customers need cheaper and higher
bandwidth backup solution
9 2006/09/07


 New circuit backup topology
Leased Line
PE
ISP
CE
xDSL
User
BRAS

Leased Line
PE
ISP
CE
FTTx
User
BRAS

FTTx
PE
ISP
CE
xDSL
10 2006/09/07 User
BRAS


 New circuit backup topology

xDSL
ISP BRAS
CE

PE wireless User

 When customers use two permanent circuits,
they hope to use these two circuits at the
same time

11 2006/09/07

Agenda

 Backup
 Load-sharing
 Multihoming
 Next challenge

12 2006/09/07

Types of redundant

 Load-sharing
 Usually use the same type of circuit
 Sometimes two circuits with the different type
but the same bandwidth is possible
 Sharing traffic among those circuits
 Redundant PE/CE (option)
 Prevent any single-point failure

13 2006/09/07

Types of redundant – Load-sharing

 Basic topology of load-sharing

Leased line
ISP
PE CE
Leased line
User

ISP
PE
X
Leased line

CE
Leased line
User

14 2006/09/07

Types of redundant – Load-sharing

 Advanced topology of load-sharing

Leased line
PE CE
ISP

PE Leased line CE
User

 Some customers think to connect to only one
SP is risky
 They need redundant option on SP issue

15 2006/09/07

Agenda

 Backup
 Load-sharing
 Multihoming
 Next challenge

16 2006/09/07

Types of redundant

 Multihoming
 Usually use the same type of circuit
 Sometimes two circuits with the different type
but the same bandwidth is possible
 Sharing traffic between those circuits
 Redundant CE (option)
 Prevent single-point failure on CE router
 Redundant service provider
 Prevent single-point failure on SP

17 2006/09/07

Types of redundant - Multihoming

 Lots of documents talks about BGP
multihoming
 Only discuss REAL cases that our customer
ask us to provision here
 Our customer uses the IP block(s) from RIR
(TWNIC) only
 seednet did not provide IP blocks for
multihoming service

18 2006/09/07


 Three ways to provision multihoming service
 Customers use BGP to exchange routing
information between SP with their AS# from
RIR
information between SP with private AS#
 Customers do not use BGP to exchange routing
information between SP

19 2006/09/07


information between SP with their AS# from
RIR
300
AS .0/20
00+ .0 ann
S1 2.20 ou
e A 17 172 nce AS
unc /21, . 3
o
ann 0.0.0 ISP1 AS100 172 20.0.0/2 00
2 .20. 1
. 0.0/
172 20
AS300
Internet 172.20.0.0/20
User
a
17 nno 300
2.2 un c e AS 21
0.8 ce oun /
.0/ AS2 ISP2 AS200 ann 2.20.8.0 /20
17 0
21
, 1 00+A 0.0.
72 1 72.2
.20 S30
.0. 0
0/2
0

 SP announce full Internet routes or default
route only to customer
20 2006/09/07


 Discussion for customers use BGP to exchange
routing information between SP with their
AS# from RIR:
 Customers have to apply AS# from RIR
 It is no necessary if those customers use their
BGP network for redundant Internet access
only (e.g. NOT for transit)
 Customers have to maintain BGP by themselves
 Not so much engineers in customer site know
well and have no fear on BGP
 Any more suitable solution?

21 2006/09/07



0
100 0/2
AS 20.0. ann
oun
ce .
n 2oun 1, 172 172 ce AS6
an .0/ ISP1 AS100 . 5
172 20.0.0/2 500
0
. 20. .20.
0.0/ 1
172 20
AS65500
Internet 172.20.0.0/20
User
500
17
2.2 ann S65
0.8 oun ce A .0/21
ISP2 AS200 oun
.0/ ce ann 72.20.8 0/20
21
, 1 AS2 1 0.0.
72 00 1 72.2
.20
.0.
0/2
0

 SP announce full Internet routes or default
route to customer
22 2006/09/07


 Customer have to maintain BGP by themselves
 Not so much engineers in customer site know
well and have no fear on BGP
 Obviously, the ability for BGP is the key
 Any solution to remove BGP here?

23 2006/09/07


 Customers do NOT use BGP to exchange
routing information between SP
export IGP
0 0 172.20.0.0/21
10 0/2
e AS 20.0. 172.20.8.0/21
ounc , 172.
ann .0/21 ISP1 AS100
.0
2 .20
17

Internet 172.20.0.0/20
User
17
2.2 ann
0.8 oun
.0/ ce ISP2 AS200
21
, 1 AS2
72 00 export IGP
.20
.0. 172.20.0.0/21
0/2
0 172.20.8.0/21

 SP does not announce any route to customer
24 2006/09/07


 Customers do not use BGP to exchange routing
information between SP
 Customer have to maintain their output traffic
by some ways
 Flow based load-sharing
» Use equal cost default route only
» Asymmetric routing status happened
 Policy-based routing (Cisco)
» Keep the symmetric routing status
» Use “PBR Recursive Next Hop” to increase the
reliability
 Filter-based forwarding (Juniper)
» Keep the symmetric routing status
» Use multiple routing table to increase the
reliability

25 2006/09/07

Agenda

 Backup
 Load-sharing
 Multihoming
 Next challenge

26 2006/09/07

Challenge to service provider

 To provide the new topology for backup and
load-sharing redundant, SP needs new
equipments and routing architecture too.
 New equipments for new circuit
 New routing architecture
 Ways to control customer routes in SP
backbone

27 2006/09/07


 In the old backup topology, backup route
would not appear in backbone
export IGP Leased Line
PE
ISP
CE
ISDN
PE User

 When the primary circuit fail, the ISDN
dial-up and change the routing status

X
export IGP
PE X
Leased Line
ISP
CE
export IGP ISDN
PE User

28 2006/09/07


 In the new backup topology, customers use
permanent circuit for backup
 Backup route leaks in the network
 Need to differentiate the primary/backup
routes in the backbone network
export iBGP, high
local-preference Leased Line
PE
ISP
CE
export iBGP, low xDSL
local-preference User
BRAS
 Have to re-configure backbone routing
topology if the old one is not suitable now

29 2006/09/07


 In the redundant load-sharing topology,
suitable routing architecture is necessary
too
export iBGP
192.168.100.0/25 high
192.168.100.128/25 low

FTTx
PE
ISP
192.168.100.0/24
xDSL CE
BRAS User
export iBGP
192.168.100.0/25 low
192.168.100.128/25 high

 Customers have to maintain default route by
themselves
30 2006/09/07

Agenda

 Backup
 Load-sharing
 Multihoming
 Next challenge

31 2006/09/07

Solution for consumers

 Basically, only enterprises will use those
redundant solution above
 Sometimes consumers/SOHO would use
Internet access for crucial purpose:
 Health and Medical Care
 Small business
 Any solution for consumers/SOHO to own
their reliable Internet access?

32 2006/09/07


 There are many “multihoming gateway”
network equipment
 The function of those equipment include:
 Load balance capacity
 Security
 VPN
 QoS
 Common service
 Basic routing
 Reliability
 ..........
33 2006/09/07


 Consumers/SOHO could buy those equipment
and use them for redundant Internet access
 This kind of redundant does NOT need the
help from SP ATU-R

ISP1 Multihoming
gateway

ATU-R

consumer
Internet ISP2 network
ATU-R

Multihoming
ISP3 gateway
ATU-R

 SP has to increase the quality to keep the
customers
34 2006/09/07

Agenda

 Backup
 Load-sharing
 Multihoming
 Next challenge

35 2006/09/07

Another redundant issue – MPLS VPN

 If customers only want to use backup or
load-sharing solution, they could use the
architectures above
 But to use multihoming solution is difficult,
Inter-AS MPLS VPN is not widespread like
Internet access
 Mostly customers use MPLS VPN for crucial
service
 How can we propose suitable solution for
MPLS VPN redundant?

36 2006/09/07


 Build redundant network on Internet
 For security reason, IPsec is required

Leased
Line CE
xDSL

PE IPsec
Tunnel BRAS

seednet
Internet
MPLS core

PE
BRAS
Leased xDSL
Line
CE

37 2006/09/07


 Build redundant network on different SP
network

Leased
Line CE
xDSL

PE
BRAS

seednet ATM
MPLS core ATM core trunk
PE
BRAS

PE
BRAS
Leased xDSL
Line
CE

38 2006/09/07


 Build redundant network on 3G network

Leased
Line CE

PE IPsec
Tunnel
seednet
MPLS core 3Gcore

PE
Leased
Line
CE

39 2006/09/07

Agenda

 Backup
 Load-sharing
 Multihoming
 Next challenge

40 2006/09/07

Next challenge

 More redundant circuit type in future?
 More redundant service provision?
 BGP anycast
 Next challenge to service provider??

41 2006/09/07

Redundant Internet service provision - customer viewpoint

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