BGP NOT RECEIVING FULL BGP

[vasquezwilmer]

Dear all

We are getting issue with one of main ISP. We used to receive more than 500K prefixes since were configured several year ago, but for some reason, currently we are receiving less than 20K prefixes. Our ISP confirmed that are sending all prefixes as well, and gave us output command from their end. I would like to know if there exists a DEBUG command that may show all event related with prefixes receiving, and what does happend if not.

Here are go out

ISP output command

#sh ip bgp neighbors 64.208.205.58 | be Prefix acti           
  Prefix activity:               ----       ----
    Prefixes Current:          533811         86 (Consumes 14960 bytes)
    Prefixes Total:         116796416         89
    Implicit Withdraw:      106657671          3
    Explicit Withdraw:        9603786          0
    Used as bestpath:             n/a         86
    Used as multipath:            n/a          0
    Saved (soft-reconfig):        n/a        101 (Consumes 8080 bytes)

RECEIVING FROM THEM

Prefix activity:               ----       ----
    Prefixes Current:             101     533817
    Prefixes Total:               245     715248
    Implicit Withdraw:            140     176910
    Explicit Withdraw:              4       4521
    Used as bestpath:             n/a          0
    Used as multipath:            n/a          0

Thank you in advance

[farhan_p2000]

Highly likely that the provider has filtered out prefixes.

If this is a Direct Internet Access link, then a default route towards service provider is all needed for outbound traffic.

Inbound traffic will be based on the network advertised by you towards service provider.

Regards,

Farhan Patel

[vasquezwilmer]

Hello farthan

Default route is no best option, becuase I have others ISP. We have our own IP Addressing assigned by LACNIC, so is full bgp is what I need. My question is if there are DEBUG COMMAND that shows prefixes comming from peering neighbor

regards

wv

[blau grana]

Hi,

Did you try to follow up this procedure?

http://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/22166-bgp-trouble-main.html#bgp_trouble_route_missing

show ip bgp neighbor x.x.x.x routes

debug ip bgp x.x.x.x updates

Also cab you please share config with all policy statements toward that peer?

[Vinit Jain]

Hello

Capturing all the updates being received from the ISP is not a good thing to do via a debug command. If there is any particular prefix that you know is missing then you can actually run a filtered debug

Below is a sample example from my presentation at Cisco Live:

route-policy DEBUG_BGP
   if destination in BGP_PREFIX then
pass 
  else
drop 
 endif
end-policy

prefix-set BGP_PREFIX 
100.1.1.0/24
end-set

debug bgp update vpnv4 unicast [in | out] route-policy DEBUG_BGP

If you dont already know the prefix, then you can try to get the below command from the ISP:

- show ip bgp nei <> advertised-routes

and based on your BGP table output, you can match which one's you having in your BGP table and which one's are missing and you can capture them in the debug accordingly.

Hope this helps.

Vinit

[Vinit Jain]

Just note the above example is in XR. If you want to run the debug in IOS, use the below:

debug ip bgp vpnv4 unicast update <neighbor> <acl> in 

access-list 10 per 100.1.1.0 0.0.0.255