Solved: Redistribution OSPF-to-BGP (Some routes not going) - Page 2

jeremyarcher · ‎08-21-2011

I'm experiencing an issue with OSPF redistribution to BGP. I have 3 sites (as seen in the diagram) - Site A, Site B and a number of remote locations represented as "Site C".

I'm attempting to redistribute routes learned from Site A (via EIGRP) through Site B's MPLS (BGP) network and vice versa. However, in looking at Site B's advertised route it only shows networks it knows about that are local. Site A's routes are not being advertised, even though they appear in the routing table an OSPF database.

Currently, I have Site A's MPLS network down (for other troubleshooting reasons).

Here is some (hopefully) helpful output:

Site B (Configuration)

----------------------------------------------------------

router bgp 1

bgp log-neighbor-changes

bgp redistribute-internal

network 10.10.10.0 mask 255.255.255.0 backdoor

network 10.10.20.0 mask 255.255.255.0 backdoor

network 10.10.30.0 mask 255.255.255.0 backdoor

network 10.10.40.0 mask 255.255.255.0 backdoor

network 10.10.50.0 mask 255.255.255.0 backdoor

network 10.10.100.0 mask 255.255.255.0 backdoor

network 10.10.109.0 mask 255.255.255.0 backdoor

network 10.10.111.0 mask 255.255.255.0 backdoor

network 10.10.112.0 mask 255.255.255.0 backdoor

redistribute connected

redistribute ospf 1 metric 110 match internal external 1 external 2 nssa-external 1 nssa-external 2 route-map To-BGP

neighbor x.x.x.x remote-as 65000

neighbor x.x.x.x default-originate

router ospf 1

redistribute bgp 1 metric 110 subnets route-map BGP-Routes

network 192.168.51.0 0.0.0.255 area 10

ip prefix-list To-BGP: 26 entries

seq 5 permit 10.10.10.0/24

seq 10 permit 10.10.20.0/24

seq 15 permit 10.10.30.0/24

seq 20 permit 10.10.40.0/24

seq 25 permit 10.10.50.0/24

seq 30 permit 10.10.100.0/24

seq 35 permit 10.10.109.0/24

seq 40 permit 10.10.111.0/24

seq 45 permit 10.10.112.0/24

seq 50 permit 172.18.1.0/24

seq 55 permit 172.18.2.0/24

seq 60 permit 192.168.100.0/24

seq 65 permit 192.168.101.0/24

seq 70 permit 192.168.102.0/24

seq 75 permit 192.168.103.0/24

seq 80 permit 192.168.104.0/24

seq 85 permit 192.168.105.0/24

seq 90 permit 192.168.106.0/24

seq 95 permit 192.168.107.0/24

seq 100 permit 192.168.108.0/24

seq 105 permit 192.168.109.0/24

seq 110 permit 192.168.110.0/24

seq 115 permit 192.168.111.0/24

seq 120 permit 192.168.113.0/24

seq 125 permit 192.168.120.0/24

seq 130 permit 192.168.121.0/24

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Site B (troubleshooting output)

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sh ip bgp neighbors x.x.x.x advertised-routes

BGP table version is 750, local router ID is 192.168.51.2

Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

r RIB-failure, S Stale, m multipath, b backup-path, x best-external, f RT-Filter

Origin codes: i - IGP, e - EGP, ? - incomplete

Originating default network 0.0.0.0

Network Next Hop Metric LocPrf Weight Path

*> 172.18.1.0/24 192.168.51.1 110 32768 ?

*> 172.18.2.0/24 192.168.51.1 110 32768 ?

*> 192.168.51.0 0.0.0.0 0 32768 ?

*> 192.168.100.0 192.168.51.1 110 32768 ?

*> 192.168.101.0 192.168.51.1 110 32768 ?

*> 192.168.102.0 192.168.51.1 110 32768 ?

*> 192.168.103.0 192.168.51.1 110 32768 ?

*> 192.168.104.0 192.168.51.1 110 32768 ?

*> 192.168.105.0 192.168.51.1 110 32768 ?

*> 192.168.106.0 192.168.51.1 110 32768 ?

*> 192.168.107.0 192.168.51.1 110 32768 ?

*> 192.168.108.0 192.168.51.1 110 32768 ?

*> 192.168.109.0 192.168.51.1 110 32768 ?

*> 192.168.110.0 192.168.51.1 110 32768 ?

*> 192.168.111.0 192.168.51.1 110 32768 ?

*> 192.168.113.0 192.168.51.1 110 32768 ?

*> 192.168.120.0 192.168.51.1 110 32768 ?

*> 192.168.121.0 192.168.51.1 110 32768 ?

This network is not getting advertised (10.10.109.0/24) nor are any other of Site A's networks (included in the route-map prefix-list above)

sh ip route 10.10.109.0

Routing entry for 10.10.109.0/24

Known via "ospf 1", distance 110, metric 110, type extern 2, forward metric 1

Redistributing via bgp 1

Advertised by bgp 1 metric 110 match internal external 1 & 2 nssa-external 1 & 2 route-map To-BGP

Last update from 192.168.51.1 on GigabitEthernet0/0, 1d21h ago

Routing Descriptor Blocks:

* 192.168.51.1, from 192.168.51.1, 1d21h ago, via GigabitEthernet0/0

Route metric is 110, traffic share count is 1

But, this network is getting redistributed (192.168.101.0/24)

sh ip route 192.168.101.0

Routing entry for 192.168.101.0/24

Known via "ospf 1", distance 110, metric 20, type extern 2, forward metric 1

Redistributing via bgp 1

Advertised by bgp 1 metric 110 match internal external 1 & 2 nssa-external 1 & 2 route-map To-BGP

Last update from 192.168.51.1 on GigabitEthernet0/0, 2d09h ago

Routing Descriptor Blocks:

* 192.168.51.1, from 192.168.51.1, 2d09h ago, via GigabitEthernet0/0

Route metric is 20, traffic share count is 1

In this output, networks that are connected or static on the Site B's ASA are being redistributed. However, networks learned via EIGRP (such as 10.10.109.0/24) on the ASA at Site B and learned via OSPF on the Site B router are not being advertised even though they are both external type 2 routes and are included in the prefix-list controlling the route-map.

Thanks in advance for any advice or recommendations!

EDIT: Updated topology drawing to show routing protocols.

jeremyarcher · ‎08-21-2011

TAC provided me with another recommendation...

At Site A and Site B create another prefix-list for the local networks.

Then, create another route-map and set the local-preference attribute to something higher (e.g. 500)

Then, under my "bgp router 1" configuration apply that route-map ("out") to my BGP neighbor command.

Peter Paluch · ‎08-22-2011

Jeremy,

Assuming the TAC knows your network more precisely than me, I would recommend following their advice.

Thanks for the updated picture. I am sorry to constantly bother you with it but I am still missing any information about the actual BGP peerings. I see the red area marked with BGP but what I need to know is:

which devices exactly are BGP neighbors (peers)
what AS are they in, and hence, if they speak internal or external BGP to each other

However, if the TAC recommendation worked then it is not necessary to rework the picture again.

Best regards,

Peter