Redistribution into BGP

[p.weeks]

When redistributing static routes into BGP does BGP use the administritive distance of the route to determine if the route should be taken into the BGP routing table? E.g the following static route was not redistributed into BGP whilst another route existed within the BGP routing table, ip route vrf VRF 10.0.0.0 255.255.255.0 atm 4/0.3263 210 tag 2100.

[mheusinger]

Hi,

the static route you gave is placed in a vrf. So you want to redistribute from the vrf IP routing table and NOT from the global IP routing table.

So did you configure

router bgp 65000

redistribute static !will NOT include the static in BGP

or

router bgp 65000

address-family ipv4 vrf VRF

redistribute static ! this WILL include the static

also make sure you do look for the proper part in the bgp table:

show ip bgp vpnv4 vrf VRF

and NOT show ip bgp

Also be aware that redistribution will only take place if the static is in the vrf IP routing table.

So if "show ip route vrf VRF" does not display the (floating) static route it will not be redistributed.

Hope this helps

Martin

[p.weeks]

Hi Martin

I had done everything you suggested. However the situation is that if I change the administrative distance of the route to default or even 200 the route is taken into bgp. If however the administrative is increased to over 200 (higher than internal bgp routes) then the static route is not imported into bgp. Do you know why?

[mheusinger]

Hello,

the command "redistribution" will always and for any routing process (connected, static, RIP, OSPF, etc.) look into the IP routing table and NOT into the configuration.

So issue a "show ip route static" or a "show ip route vrf VRFname static" - depending on context - to check what will be redistributed.

In your case the static route probably is not entered into the VRF IP routing table because of administrative distance. Then redistribution will not occur.

Hope this helps! Please rate all posts

Martin

[olorunloba]

As further clarification to the above post,

"Note: The mechanics of route redistribution is proprietary on Cisco routers. The rules for redistribution on a Cisco router dictate that the redistributed route be present in the routing table. It is not sufficient that the route be present in the routing topology or database. Routes with a lower Administrative Distance (AD) are always installed in the routing table. For example, if a static route is redistributed into IGRP on R5, and then IGRP subsequently redistributed into RIP on the same router (R5), the static route is not redistributed into RIP because it never got entered into the IGRP routing table. This is due to the fact that static routes have an AD of 1 and IGRP routes have an AD of 100 and the static route is installed in the routing table. To redistribute the static route into IGRP on R5, you need to use the redistribute static command under the router rip command."

The above is gotten from

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009487e.shtml

[p.weeks]

If I understand you correctly then the route will not be redistributed into BGP because a better route exsists in the routing table (lower AD). I will therefore not see this route with the show ip bgp vpnv4 vrf VRF command unless it has an eqivalent og lower AD than the route coming via BGP. Is this a correct interpretation?

[olorunloba]

Correct sir. The configured static route will not be redistributed, unless it has been entered into the routing table. This applies to other routing protocol as well.

Hence, if a route is in the EIGRP topology database, but not in the routing table (maybe because you know the route via static, a better AD), redistributing eigrp into another protocol say BGP will not redistribute the route.