difference between received-only and received&used about BGP.

[syjeon]

Hi,

I need to know exacly about subjected. Can anyone explain about what is the difference when we execute 'show ip bgp x.x.x.x' ?                  

[milan.kulik]

Hi,

Inbound Soft-Reconfiguration is configured on your router probably.

Read

http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a00800949e8.shtml#qbgp

and

http://www.cisco.com/en/US/customer/docs/ios/12_4t/ip_route/configuration/guide/t_brbbas.html#wp1105512

for details.

HTH,

Milan

[blau grana]

Hi

Difference between received-only and received&used -> I do not know if theese are official terms or not, but here you should find answer, slide #3 - #6:

http://meetings.ripe.net/ripe-45/presentations/ripe45-routing-bgp-update.pdf

received-only -> will not make it into routing table

#4 - prefix is filtered

#5 - prefix is not the best among received

received&used -> are placed into routing table and advertised to neighbours

Best Regards

Please rate helpful posts

[Peter Koltl · Accepted solution]

received-only:

the prefix  from a soft-reconfiguration-enabled peer was filtered by our route-map so not placed into regular BGP table. It is still held in memory in case someone changes the filtering config and the prefix gains the right to go into BGP table without requesting an update (by sending REFRESH_REQ) from the peer:

R3#sh ip bgp 1.1.1.6

BGP routing table entry for 1.1.1.6/32, version 0

Paths: (1 available, no best path)

  Not advertised to any peer

  4 5 6, (received-only)

    2.34.34.4 from 2.34.34.4 (1.0.0.4)

      Origin IGP, localpref 100, valid, external

(show ip bgp   command does  not show this prefix)

received & used:

the prefix  from a soft-reconfiguration-enabled peer was not filtered by our route-map so it is placed into regular BGP table. It is not necessarily the best path so not necessarily placed into the routing table.

R4(config-router)#do sh ip bgp 1.0.0.5/32

BGP routing table entry for 1.0.0.5/32, version 4

Paths: (2 available, best #2, table default)

  Advertised to update-groups:

     1

  3, (received & used)

    2.34.34.3 from 2.34.34.3 (1.0.0.3)

      Origin IGP, metric 0, localpref 100, valid, external

  5, (received & used)

    2.45.45.5 from 2.45.45.5 (1.0.0.5)

      Origin IGP, metric 0, localpref 100, valid, external, best

R4(config-router)#do show ip route 1.0.0.5 255.255.255.255 lo

B        1.0.0.5 [20/0] via 2.45.45.5, 00:35:20