Re: Reading show ip bgp summary

josephp · ‎11-10-2010

Hi Folks,

I need a little help, I'm trying to understand the output of "show ip bgp summary". I have a dual homed setup with 2 provider and both claimed that they are not using community. I do however see that there are "206 BGP communities using 12616 bytes of memory" when I issue the show ip bgp summary command.

core01.nj3-1.sup#sh ip bgp vpnv4 vrf vrf_internet summary
BGP router identifier <SNIP>, local AS number SNIP
BGP table version is 2527, main routing table version 2527
884 network entries using 124644 bytes of memory
885 path entries using 60180 bytes of memory
617/167 BGP path/bestpath attribute entries using 86380 bytes of memory
456 BGP AS-PATH entries using 13700 bytes of memory
206 BGP community entries using 12616 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 297520 total bytes of memory
BGP activity 1024/140 prefixes, 1070/185 paths, scan interval 15 secs

Neighbor        V    AS MsgRcvd MsgSent   TblVer InQ OutQ Up/Down State/PfxRcd
X.X.X.X           4 27506 256642   11327     2527    0    0 1w0d          519
X.X.X.X           4 46887 1015641   19982     2527    0    0 1w0d          365
core01.nj3-1.sup#

Thank you in advanced I appreciate it.

JP

Peter Paluch · ‎11-10-2010

Hi Joseph,

What does the output of the show ip bgp community command say? Select any network from this output and use the show ip bgp command to display the details about it, e.g.:

route-views>show ip bgp 1.1.1.0 255.255.255.0
BGP routing table entry for 1.1.1.0/24, version 1586788750
Paths: (32 available, best #21, table Default-IP-Routing-Table)
Not advertised to any peer
8075 701 703
    207.46.32.34 from 207.46.32.34 (207.46.32.34)
      Origin IGP, localpref 100, valid, external
3277 3216 702 703
    194.85.102.33 from 194.85.102.33 (194.85.4.16)
      Origin IGP, localpref 100, valid, external
      Community: 3216:3000 3216:3002 3277:3216
2828 701 703
    65.106.7.139 from 65.106.7.139 (66.239.189.139)
      Origin IGP, metric 3, localpref 100, valid, external
6079 3356 701 703

The highlighted line indicates that this network learned from 194.85.102.33 does have certain communities set. You can verify your networks in the similar way.

Best regards,

Peter

josephp · ‎11-11-2010

Hi Peter,

Thank you for the update, I did issue that command however I did not get any routes.

router01#
router01#sh ip bgp vpnv4 vrf vrf_internet summary
BGP router identifier , local AS number
BGP table version is 561, main routing table version 561
548 network entries using 77268 bytes of memory
549 path entries using 37332 bytes of memory
16/11 BGP path/bestpath attribute entries using 2240 bytes of memory
3 BGP AS-PATH entries using 88 bytes of memory
3 BGP community entries using 120 bytes of memory
3 BGP route-map cache entries using 96 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 117144 total bytes of memory
BGP activity 552/4 prefixes, 554/5 paths, scan interval 15 secs

Neighbor        V    AS MsgRcvd MsgSent   TblVer InQ OutQ Up/Down State/PfxRcd
        4 27506   63215     244      561    0    0 03:49:32      519
        4 46887   79779     454      561    0    0 03:49:28       29
router01#

router01#sh ip bgp vpnv4 vrf vrf_internet community

router01#

Peter Paluch · ‎11-11-2010

Hi Joseph,

Oh, I apologize, I did not notice the first time that you are running your BGP with a VRF.

I believe that the VRF is actually the reason why you see some communities being stored in your BGP memory. The route-target that is configured for each VRF is actually an extended community attribute, and I believe that what we see in your BGP summary output is the memory allocated for the route-target values.

Best regards,

Peter

Tharak Abraham · ‎11-11-2010

Maybe you need a "show ip bgp vpnv4 all "

or

even "sh ip bgp vpnv4 vrf vrf_internet summary " in you context

This will show the extended community atrributes for your ref.