11. RIP interface summaries cause routing loops hostname A1 ! interface Loopback0 ip address 10.0.1.1 255.255.255.255 ! interface FastEthernet0/0 description LAN 0 (A1-A2) ip address 10.2.1.1 255.255.255.0 ! interface Serial1/0 description Link to R1(ROUTER) S1/0 ip address 10.0.7.9 255.255.255.252 ip summary-address rip 10.0.1.0 255.255.255.0 ! router rip version 2 network 0.0.0.0
12. RIP interface summaries cause routing loops A2#show ip route rip 10.0.0.0/8 is variably subnetted, 9 subnets, 3 masks R 10.0.7.8/30 [120/1] via 10.2.1.1, 00:00:01, FastEthernet0/0 R 10.0.1.1/32 [120/1] via 10.2.1.1, 00:00:01, FastEthernet0/0 R 10.0.1.0/24 [120/3] via 10.0.7.14, 00:00:04, Serial1/0 R 10.0.1.5/32 [120/1] via 10.0.7.14, 00:00:04, Serial1/0 R 10.0.1.4/32 [120/2] via 10.2.1.1, 00:00:01, FastEthernet0/0 [120/2] via 10.0.7.14, 00:00:04, Serial1/0 R 10.0.7.20/30 [120/1] via 10.0.7.14, 00:00:04, Serial1/0 A1#show ip route rip 10.0.0.0/8 is variably subnetted, 11 subnets, 3 masks R 10.0.1.0/24 [120/4] via 10.2.1.2, 00:00:02, FastEthernet0/0 R 10.0.1.2/32 [120/1] via 10.2.1.2, 00:00:02, FastEthernet0/0 R 10.0.1.4/32 [120/1] via 10.0.7.10, 00:00:04, Serial1/0 R 10.0.1.5/32 [120/2] via 10.2.1.2, 00:00:02, FastEthernet0/0 [120/2] via 10.0.7.10, 00:00:04, Serial1/0 R 10.0.7.12/30 [120/1] via 10.2.1.2, 00:00:02, FastEthernet0/0 R 10.0.7.20/30 [120/1] via 10.0.7.10, 00:00:04, Serial1/0
14. RIP interface summaries cause routing loops A2#show ip route rip 10.0.0.0/8 is variably subnetted, 8 subnets, 3 masks R 10.0.7.8/30 [120/1] via 10.2.1.1, 00:00:05, FastEthernet0/0 R 10.0.1.1/32 [120/1] via 10.2.1.1, 00:00:05, FastEthernet0/0 R 10.0.1.5/32 [120/1] via 10.0.7.14, 00:00:07, Serial1/0 R 10.0.1.4/32 [120/2] via 10.2.1.1, 00:00:05, FastEthernet0/0 [120/2] via 10.0.7.14, 00:00:07, Serial1/0 R 10.0.7.20/30 [120/1] via 10.0.7.14, 00:00:07, Serial1/0
29. EIGRP Stub leak maps R1: router eigrp 10 network 150.1.12.1 0.0.0.0 network 150.1.13.1 0.0.0.0 network 150.1.14.1 0.0.0.0 eigrp stub connected no auto-summary ! R2: router eigrp 10 network 150.1.12.2 0.0.0.0 no auto-summary R3: router eigrp 10 network 150.1.13.3 0.0.0.0 auto-summary R4: router eigrp 10 network 150.1.14.4 0.0.0.0 no auto-summary redistribute rip met 1 1 1 1 1 router rip redistribute eigrp 10 met 1 R2#sh ip route eigrp 150.1.0.0/24 is subnetted, 3 subnets D 150.1.14.0 [90/2195456] via 150.1.12.1, 00:00:23, Serial1/0 D 150.1.13.0 [90/2195456] via 150.1.12.1, 00:00:23, Serial1/0 R3#sh ip route eigrp 150.1.0.0/24 is subnetted, 3 subnets D 150.1.14.0 [90/307200] via 150.1.13.1, 00:01:15, Ethernet0/0 D 150.1.12.0 [90/2195456] via 150.1.13.1, 00:01:15, Ethernet0/0
30. EIGRP Stub leak maps access-list 1 permit 5.5.0.0 0.0.0.255 access-list 1 permit 5.5.1.0 0.0.0.255 route-map EIGRP_LEAK match ip address 1 router eigrp 10 eigrp stub connected leak-map EIGRP_LEAK R2#sh ip route eigrp 5.0.0.0/24 is subnetted, 2 subnets D EX 5.5.0.0 [170/2560537856] via 150.1.12.1, 00:00:28, Serial1/0 D EX 5.5.1.0 [170/2560537856] via 150.1.12.1, 00:00:28, Serial1/0 150.1.0.0/24 is subnetted, 3 subnets D 150.1.14.0 [90/2195456] via 150.1.12.1, 00:00:28, Serial1/0 D 150.1.13.0 [90/2195456] via 150.1.12.1, 00:00:28, Serial1/0 R3#sh ip route eigrp 5.0.0.0/24 is subnetted, 2 subnets D EX 5.5.0.0 [170/2560051456] via 150.1.13.1, 00:00:20, Ethernet0/0 D EX 5.5.1.0 [170/2560051456] via 150.1.13.1, 00:00:20, Ethernet0/0 150.1.0.0/24 is subnetted, 3 subnets D 150.1.14.0 [90/307200] via 150.1.13.1, 00:00:20, Ethernet0/0 D 150.1.12.0 [90/2195456] via 150.1.13.1, 00:00:20, Ethernet0/0
52. External default route in NSSA area ABR-A#show ip ospf database nssa-external | exclude LS|Check OSPF Router with ID (10.0.1.9) (Process ID 1) Type-7 AS External Link States (Area 22) Options: (No TOS-capability, Type 7/5 translation, DC) Link State ID: 0.0.0.0 (External Network Number ) Advertising Router: GW Length: 36 Network Mask: /0 Metric Type: 1 (Comparable directly to link state metric) Metric: 100 Forward Address: 10.0.1.8 External Route Tag: 0 B1#show ip ospf database external | exclude LS|Check OSPF Router with ID (172.16.1.1) (Process ID 1) Type-5 AS External Link States Options: (No TOS-capability, DC) Link State ID: 0.0.0.0 (External Network Number ) Advertising Router: ABR-A Length: 36 Network Mask: /0 Metric Type: 1 (Comparable directly to link state metric) Metric: 100 Forward Address: 10.0.1.8 External Route Tag: 0
53. OSPF Filtering area area-id range ip-address mask not-advertise Interface interface ip ospf database-filter all out 150.1.0.0/16
54. OSPF Filtering based on next hop R1#sh ip route 2.2.2.0 Routing entry for 2.2.2.0/24 Known via "ospf 1", distance 110, metric 74, type intra area Last update from 192.168.1.1 on Serial1/0, 00:00:46 ago Routing Descriptor Blocks: 192.168.1.2 , from 192.168.1.2 , 00:00:46 ago, via Serial1/0 Route metric is 74, traffic share count is 1 * 192.168.1.3 , from 192.168.1.3 , 00:00:46 ago, via Serial1/0 Route metric is 74, traffic share count is 1
55. OSPF Filtering based on next hop router ospf 1 distribute-list route-map ROUTE_FROM_R2 in ! access-list 2 permit 192.168.1.2 ! access-list 12 permit 2.2.2.0 0.0.0.255 ! route-map ROUTE_FROM_R2 deny 10 match ip address 12 match ip next-hop 2 ! route-map ROUTE_FROM_R2 permit 20 R3#sh ip route 2.2.2.0 Routing entry for 2.2.2.0/24 Known via "ospf 1", distance 110, metric 74, type intra area Last update from 192.168.1.1 on Serial1/0, 00:00:46 ago Routing Descriptor Blocks: 192.168.1.3 , from 192.168.1.3 , 00:00:46 ago, via Serial1/0 Route metric is 74, traffic share count is 1
56. OSPF Type 3 LSA Filtering Router(config)# router ospf 1 log-adjacency-changes area 1 filter-list prefix AREA_1_OUT out area 3 filter-list prefix AREA_3_IN in network 10.0.0.0 0.255.255.255 area 3 network 172.16.1.0 0.0.0.255 area 0 network 192.168.0.0 0.255.255.255 area 1 ! ip prefix-list AREA_1_OUT seq 10 permit 10.25.0.0/8 ge 16 ip prefix-list AREA_1_OUT seq 20 permit 172.20.20.0/24 ! ip prefix-list AREA_3_IN seq 10 permit 172.31.0.0/16