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BGP route not being advertised

adil.javid
Level 1
Level 1

Hello,

I have a route that I am trying to advertise to an external provider via BGP, but with no success.

- This is an EBGP connection;

- I have the route in my IGP table (OSFP);

- I have given the network statement in BGP to advertise the route;

- I have modified the prefix-list to include the new route to advertise.

However, even after all these changes above I cannot see the route being advertised to the provider.

Does anyone know what could be causing this issue please???

Thank in advance.

23 Replies 23

Jon Marshall
Hall of Fame
Hall of Fame

Hi

Could you post relevant BGP config and a copy of the routing table.

Jon

Sure, here is the relevant config:

network 211.14.0.0 route-map set-med-xxx-xxx

neighbor 199.72.199.12 remote-as 64960

neighbor 199.72.199.12 password 7 131610401F045427387426

neighbor 199.72.199.12 update-source Vlan70

neighbor 199.72.199.12 soft-reconfiguration inbound

neighbor 199.72.199.12 prefix-list ThomsonFinancial_Accept in

neighbor 199.72.199.12 prefix-list SG-To-Thomson out

Prefix-list:

ip prefix-list SG-To-Thomson seq 70 permit 211.14.0.0/16

Routing table:

xxxxx#sh ip bgp

*> 211.14.0.0 193.10.200 100 32768 i

Hi

If you do a "sh ip route" is there an entry there. Could you post it.

Jon

Yes, it is present in the IGP table:

xxxxx#sh ip route | i 211.14.0.0

O IA 211.14.0.0/16 [110/212] via 193.10.200 , 1w5d, Vlan10

Thanks

Hi

Sorry to keep asking for things but could you post full config of router as there is a route-map entry for example that is not included.

Jon

Hello,

No problem, I appreciate your help. The route-map is as follows:

*******************

route-map set-med-xxx-xxx permit 10

set metric 100

*******************

Thanks.

Hi

I really need the full BGP config etc.

If you can't send it have a look at this doc on BGP troubleshooting - there is a specific bit about BGP advertising and network statements

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009478a.shtml#bgp_trouble_route_adv

Jon

Hello,

Try to avoid using the include in combination with the ip route command as you just did.

If the router that you issue such a command to also happens to have a large number of routes, you can potentially freeze the poor machine.

It is much safer and you even type less characters if you just type in: show ip route 211.14.0.0

This was obviously not a suggestion for solution of a problem that has already been solved. It just reminded me of my first big mistake in a router that was carrying many thousands of routes.

Kind Regards,

M.

Hi,

I see a discreapancy in the subnet mask used:

ip prefix-list SG-To-Thomson seq 70 permit 211.14.0.0/16

but

network 211.14.0.0 route-map set-med-xxx-xxx

Which means /24 mask used if nothing else specified.

If I understand correctly,

network 211.14.0.0 mask 255.255.0.0 route-map set-med-xxx-xxx

should have been used.

BR,

Milan

hai,

the AS which you mentoned as remote AS 64960 ...when i serched using the (http://fixedorbit.com/search.htm)

getting below error message ..

This AS is not currently in use.

.... guys correct me if i am wrong

Lijesh.N.C

Hi,

ASN 64512 to 65534 is reserved by IANA for private use.

It can be use by SP and its downstream if the downstream doesn't have its own AS.

Regards,

Dandy

Hai Dandy,

I was little confused with Privet As and Public ....now its clear ..that was my mistake ...thanks a lot

Lijesh.N.C

mheusing
Cisco Employee
Cisco Employee

Hi,

a couple of basic questions:

1) your BGP session is up, I guess?

2) How do you check that the route is not advertised?

3) your prefix-list statement has seq 70, post everything up to that entry!

4) Is the provider applying input filters blocking 211.14/16?

As a general remark: please do not cut or edit outputs unless you need to for security reasons. In this case, please replace the relevant statements.

I am assuming you would not be posting here, if you would not look for help. This usually means, that something relevant to the problem is not seen or understood. In this case to only post, what you are thinking is important will likely not reveal the underlying problem.

Regards, Martin

Danilo Dy
VIP Alumni
VIP Alumni

Hi,

After you've done with Milan and Martin's recommendation, don't forget to reset BGP so that your upstream will receive the changes that you've made. i.e.

clear ip bgp 199.72.199.12 soft out

Another recommendation (not related to your problem) is to use aggregation. i.e.

aggregate-address 211.14.0.0 255.255.0.0 summary-only

BTW, I see it being advertise as 211.14/21 using RIPE looking-glass. Are you changing the current advertisement from /21 to /16?

Regards,

Dandy

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