From: Michael Stout (michaelgstout@hotmail.com)
Date: Sat Jul 15 2006 - 17:44:24 ART
I think your ospf will improve if you add the following comamnd to the
serial interface
ip ospf priority 255
If you are trying to peer R4 to R5 you will need the ebgp multihop
command on your neighbor statements.
--------------------------------------------------------------------
From: "Radoslav Vasilev" <deckland@gmail.com>
Reply-To: "Radoslav Vasilev" <deckland@gmail.com>
To: "Cisco certification" <ccielab@groupstudy.com>
Subject: OSPF P2M non-broadcast interface issues
Date: Sat, 15 Jul 2006 14:36:28 +0100
Hi Group,
This is mostly for the IEWB Team to check, but any other opinion
appreciated.
Currnetly working on IEWB Lab 16, task 5.1 which is BGP
configurations.
One of my adjacency woldn't come up (eBGP session over FR cloud), due
to TTL
expiration (no ebgp-multihop configured as the neighbors are directly
connected).
Starting from this issue, i went back to my OSPF configuration. First
the
setup:
R3, R4 and R5 in a hub-and-spoke toplogy with R3 being the hub. All
devices
use physical interfaces and the requirenments say no broadcast for
the
frame-relay maps(no inverse arp as well). Common IP subnet over this
toplogy. My configuration:
R3, the hub:
interface Serial1/0
ip address 154.1.0.3 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint non-broadcast
clock rate 64000
frame-relay map ip 154.1.0.4 304
frame-relay map ip 154.1.0.5 305
no frame-relay inverse-arp
R4, a spoke:
interface Serial0/0
ip address 154.1.0.4 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint non-broadcast
clock rate 64000
frame-relay map ip 154.1.0.3 403
frame-relay map ip 154.1.0.5 403
no frame-relay inverse-arp
R5, a spoke:
interface Serial0/0
ip address 154.1.0.5 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint non-broadcast
clock rate 64000
frame-relay map ip 154.1.0.3 503
frame-relay map ip 154.1.0.4 503
no frame-relay inverse-arp
I have connectivity between the devices and now i need to configure
OSPF
adjacencie. Pasting only the configuration of R3:
router ospf 100
router-id 150.1.3.3
log-adjacency-changes
area 3457 filter-list prefix area3457in in
timers throttle spf 4000 10000 90000
network 150.1.3.3 0.0.0.0 area 3457
network 154.1.0.3 0.0.0.0 area 3457
network 154.1.38.3 0.0.0.0 area 38
network 0.0.0.0 255.255.255.255 area 0
neighbor 154.1.0.4 cost 97
neighbor 154.1.0.5 cost 195
As shown above, R3 is manually configured with R4 and R5 as OSPF
neighbors
over what is configured as P2M non-broadcast network (because of
another lab
requrement the cost to the two neighbors are not equal).
My troubles begin when i configure the two neighbors on R3 with
different
costs, as then the FR interface address of R5 (154.1.0.5) starts to
be seen
through R4 (from R3 perspective). This is because R4 and R5 have
another
OSPF link, over which R4 learns about R5's FR interface. Because now
R3
routes through R4 for the R5's address:
Rack1R3#sh ip route 154.1.0.5
Routing entry for 154.1.0.5/32
Known via "ospf 100", distance 110, metric 98, type intra area
Last update from 154.1.0.4 on Serial1/0, 00:07:06 ago
Routing Descriptor Blocks:
* 154.1.0.4, from 150.1.5.5, 00:07:06 ago, via Serial1/0
Route metric is 98, traffic share count is 1
the eBGP won't come up.
At the same time I don't see anything in the solultion that would
overcome
this.
Rado
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This archive was generated by hypermail 2.1.4 : Tue Aug 01 2006 - 07:13:47 ART