11-25-2008 11:47 AM - edited 03-04-2019 12:29 AM
Router G is connected out its Tok0 interface to the 10.4.4.0/24 subnet (its interface IP is 10.4.4.7).
Router A is connected to Router G via a 30-bit Serial link. Each has each other in its OSPF neighbor table in the full state.
The 10.4.4.0 link is up and active, is declared in the OSPF process (evident under both show ip prot and show running), yet it WILL NOT APPEAR in Router A's routing table.
Router A's info:
Sethtek-A#sh ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
215.0.0.13 1 FULL/ - 00:01:57 215.0.0.13 Serial0
Sethtek-A#show run
interface Serial0
ip address 215.0.0.14 255.255.255.252
no ip directed-broadcast
encapsulation ppp
no ip route-cache
ip ospf hello-interval 30
no ip mroute-cache
no fair-queue
clockrate 1000000
!!!!!output omitted!!!!!
!
interface Serial1
ip address 215.0.0.6 255.255.255.252
no ip directed-broadcast
encapsulation ppp
no ip route-cache
no ip mroute-cache
no fair-queue
!
router ospf 100
network 215.0.0.12 0.0.0.3 area 0
!
ip default-gateway 215.0.0.14
ip classless
!
tftp-server flash:c2500-i-l.120-8.bin
Solved! Go to Solution.
11-25-2008 12:40 PM
Seth,
The issue is that there is an ospf network type mismatch. This will not prevent the adjacency from forming but will prevent the routes learned from this neighbor to be used by ospf. Remove the "ip ospf network non-broadcast" under serial0 of router G and it should fix the issue you are seeing.
Regards
11-25-2008 11:51 AM
And Router G's info:
Sethtek-G#sh ip pro
Routing Protocol is "ospf 100"
Invalid after 0 seconds, hold down 0, flushed after 0
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Routing for Networks:
10.4.4.0/24
215.0.0.12/30
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 110)
Sethtek-G>sh ip ospf nei
Neighbor ID Pri State Dead Time Address Interface
205.1.3.1 1 FULL/BDR 00:01:55 215.0.0.14 Serial0
Sethtek-G# sh run
!!!output omitted!!!
!
interface Serial0
ip address 215.0.0.13 255.255.255.252
encapsulation ppp
ip ospf network non-broadcast
no ip mroute-cache
no fair-queue
!
interface Serial1
no ip address
encapsulation ppp
!
interface TokenRing0
ip address 10.4.4.7 255.255.255.0
ip ospf priority 200
ip policy route-map word
ring-speed 16
!
router ospf 100
log-adjacency-changes
network 10.4.4.0 0.0.0.255 area 0
network 215.0.0.12 0.0.0.3 area 0
!
router bgp 50
bgp log-neighbor-changes
network 10.4.4.0
neighbor 10.4.4.8 remote-as 50
neighbor 215.0.0.14 remote-as 100
!
ip kerberos source-interface any
ip classless
ip route 10.2.2.0 255.255.255.0 10.5.5.1
no ip http server
!
access-list 1 permit 172.16.0.2
route-map Toby permit 10
match ip next-hop 1
set weight 100
!
!
tftp-server flash:aaa0850.bin
As indicated, these are partial clippings from the running config; but I think all the relevant stuff is here.
10.4.4.0 is up and running on Router G, it's declared in the OSPF process, and Router G has full neighborship with Router A so WHY is Router A not getting the route to 10.4.4.0?
11-25-2008 11:53 AM
Can you post the full "sh ip route?"
John
11-25-2008 11:55 AM
Sethtek-A#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
C 205.1.1.0/24 is directly connected, Loopback1
C 205.1.0.0/24 is directly connected, Loopback0
C 205.1.3.0/24 is directly connected, Loopback3
C 205.1.2.0/24 is directly connected, Loopback2
215.0.0.0/24 is variably subnetted, 2 subnets, 2 masks
C 215.0.0.13/32 is directly connected, Serial0
C 215.0.0.12/30 is directly connected, Serial0
Sethtek-A#
PLUS
Sethtek-G#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
215.0.0.0/24 is variably subnetted, 2 subnets, 2 masks
C 215.0.0.14/32 is directly connected, Serial0
C 215.0.0.12/30 is directly connected, Serial0
10.0.0.0/24 is subnetted, 1 subnets
C 10.4.4.0 is directly connected, TokenRing0
Sethtek-G#
11-25-2008 12:40 PM
Seth,
The issue is that there is an ospf network type mismatch. This will not prevent the adjacency from forming but will prevent the routes learned from this neighbor to be used by ospf. Remove the "ip ospf network non-broadcast" under serial0 of router G and it should fix the issue you are seeing.
Regards
11-25-2008 12:44 PM
WOW! I will try that, but before I do - what the heck is Cisco's (or the RFC 2328 authors') logic behind allowing adjacencies to form over mismatched network types; if that's going to prevent good routes from gettin in?
11-25-2008 01:28 PM
Seth,
This is not a Cisco issue but rather an RFC2328 issue. Unlike some other attibutes (i.e. MTU, network address, capabilities, etc), the network type is not negotiated. I suppose the reason for it is that in certain cases it would be normal to have different network types on either side of the adjacency (point-to-multipoint vs point-to-point for instance).
Regards
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