From: Jung-I Lin (easyman.lin@gmail.com)
Date: Tue Sep 26 2006 - 06:34:47 ART
Hi, Groups
I'm doing IE Lab Vol2 Lab3, and find a interesting problem in relate to
OSPF.
The secnario is 3 routers R1,R3,R5 connected in a hub-and-spoke
topology(OSPF Area 135 in this case) with R3 as the HUB.
R1&R5 only have dynamic inver-arp to R3.
R3 have both dynamic map to R1 & R5.
The ospf network type is configured as "p2mp nonbroadcast".
Obviously we need "neighbor" command on it to establish the adjacency, I put
2 "neighbor" command on R3 point to R1&R5.
But problem will aries after the other requirement is configured, R3 need to
have virtual-link across this frame-relay network.
The virutal-link is R1-R3,R3-R5. I configured the virtual-link on R1,R3,R5.
At this moment everything seem okay, but after reloading R3 the "neighbor"
command will not show in "show running", but It will show in "show startup".
It seems that IOS reject this command, I tried to put it into ospf process
and the error messages appear.
see below
Rack10R3#show running | b router ospf
router ospf 1
router-id 150.10.3.3
log-adjacency-changes
area 0 authentication message-digest
area 34 stub no-summary
area 135 virtual-link 150.10.1.1 message-digest-key 1 md5 CISCO
area 135 virtual-link 150.10.5.5 message-digest-key 1 md5 CISCO
redistribute rip subnets
network 150.10.3.3 0.0.0.0 area 0
network 190.10.34.3 0.0.0.0 area 34
network 190.10.43.3 0.0.0.0 area 0
network 190.10.135.3 0.0.0.0 area 135
Rack10R3#c
Enter configuration commands, one per line. End with CNTL/Z.
Rack10R3(config)#router ospf 1
Rack10R3(config-router)#neig 190.10.135.1
OSPF: Neighbor command is allowed only on NBMA and point-to-multipoint
networks
Rack10R3(config-router)#
Rack10R3#sh ip ospf int s1/0
Serial1/0 is up, line protocol is up
Internet Address 190.10.135.3/24, Area 135
Process ID 1, Router ID 150.10.3.3, Network Type POINT_TO_MULTIPOINT,
Cost: 781
Rack10R3#sh run int s1/0
Building configuration...
Current configuration : 411 bytes
!
interface Serial1/0
ip address 190.10.135.3 255.255.255.0
ip pim nbma-mode
ip pim sparse-dense-mode
encapsulation frame-relay
ip ospf authentication message-digest
ip ospf message-digest-key 2 md5 CISCO35
ip ospf message-digest-key 1 md5 CISCO13
ip ospf network point-to-multipoint non-broadcast
If you remove both of the "virtual-link" statement, the neighbor will be
accepted without any complaints.
see below
Rack10R3(config-router)#no area 135 virtual-link 150.10.1.1
Rack10R3(config-router)#neig 190.10.135.1
OSPF: Neighbor command is allowed only on NBMA and point-to-multipoint
networks (there still one "virtual-link" left, so the command still be
rejected)
Rack10R3(config-router)#no area 135 virtual-link 150.10.5.5
Rack10R3(config-router)#neig 190.10.135.1 (both "virtual-link" command are
removed, and the "neighbor" command in entered without error
messages.)
Rack10R3(config-router)#
But if you reaply the "virtual-link" into ospf process and reboot the
router, the whole process will startover again.
I tried to search the GS archive to find if someone have solved this
problem, but I didn't find one.
Then I search through CCO Bug toolkit and find this, God it took me almost 3
hours.
HTH.
I hope I will not encounter this bug in the real lab.
Bugid=CSCse72792
http://www.cisco.com/cgi-bin/Support/Bugtool/onebug.pl?bugid=CSCse72792&cco_product=IOS&fset=OSPF&swver=&keyw=neighbor&target=&train=
-- Thanks Best Regards,Jung-I Lin
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