Route redistribution

[beta_admin66]

Hi,

I would like to redistribute BGP and EIGRP mutually:

R1 - R2 EIGRP AS 100
R2 - R3 BGP AS 100

R2:
Router EIGRP 100
default-metric 1000000 1 255 1 1500
Network 10.12.1.0 0.0.0.255
redistribute bgp 100 metric 1000000 1 255 1 1500
!
Router BGP 100
BGP Router ID 2.2.2.2
bgp log-neighbor-changes
bgp redistribute-internal
redistribute EIGRP 100
neighbor 10.23.1.2 remote-as 100
!

But I don't see any routes from EIRGRP on the router R3 and no routes from BGP to R1.

Can you help me?

Thanks

[MHM Cisco World]

bgp redistribute-internal <<- You already use this command so skip this step

Add also

Neighbor x.xx.x next-hop-self

MHM

MHM

[MHM Cisco World]

next-hop-self if only what you need additional 

check lab below

MHM

[paul driver]

Hello @MHM Cisco World 
The next-hop-self will help with the transit connectivity  but it should NOT negate the advertisement of the routes, so if the OP is stating they are not receiving any routes after redistribution then its something other than applying the next-hop-self, hence in this instance as we dont not see whole configuration picture  they could manually specify the RIDs of the routing process just to make sure they are not being duplicated as this can cause unwarranted filtering

[MHM Cisco World]

Hi Paul 
but it should NOT negate the advertisement of the routes <<- if he dont use next-hop-self then the bgp will reject the prefix since the next hop is unreachable. 
so we use next-hop-self to make ibgp change the next-hop of eigrp prefix to IP reachable from the neighbor

MHM

[paul driver]

Helllo @MHM Cisco World 
But It won’t negate the redistribution of the routes worst case the bgp rtr just wont enter the prefixes in the GRT.
There is a difference between receiving routes and having those routes being reachable so much so they can be received but not reachable 

[MHM Cisco World]

No friend 

Select BGP Best Path Algorithm - Cisco

Why Routers Ignore Paths

Assume that all paths that a router receives for a particular prefix are arranged in a list. The list is similar to the output of the show ip bgp longer-prefixes command. In this case, some paths are not considered as candidates for the best path. Such paths typically do not have the valid flag in the output of the show ip bgp longer-prefixes command. Routers ignore paths in these circumstances:

• Paths that are marked as not synchronized in the show ip bgp longer-prefixes output.

  If BGP synchronization is enabled, there must be a match for the prefix in the IP routing table in order for an internal BGP (iBGP) path to be considered a valid path. BGP synchronization is enabled by default in Cisco IOS^® Software. If the route that matches is learned from an Open Shortest Path First (OSPF) neighbor, its OSPF router ID must match the BGP router ID of the iBGP neighbor. Most users prefer to disable synchronization with use of the no synchronization BGP subcommand.

  Note: Synchronization is disabled by default in Cisco IOS® Software Release 12.2(8)T and later.

• Paths for which the NEXT_HOP is inaccessible.

  Be sure that there is an Interior Gateway Protocol (IGP) route to the NEXT_HOP that is associated with the path.

• Paths from an external BGP (eBGP) neighbor if the local autonomous system (AS) appears in the AS_PATH. 

  Such paths are denied upon ingress into the router, and are not even installed in the BGP Routing Information Base (RIB). The same applies to any path that is denied by a routing policy that is implemented via access, prefix, AS_PATH, or community lists, unless you have configured neighbor soft-reconfiguration inbound for the neighbor.

• If you enabled bgp enforce-first-as and the UPDATE does not contain the AS of the neighbor as the first AS number in the AS_SEQUENCE.

  In this case, the router sends a notification and closes the session.

• Paths that are marked as (received-only) in the show ip bgp longer-prefixes output

  The policy has rejected these paths. However, the router has stored the paths because you have configured soft-reconfiguration inbound for the neighbor that sends the path.

[paul driver]

Hello @MHM Cisco World 
in this instance it does not matter as the next-hop from the redistribution points are valid - (the directly connected interfaces of rtr2 in either direction) so from rtr3 perspective if the nexthop-self wasn’t applied towards it it would have next hop of the rtr2-rt1 interface but the route should still be advertised to it any case 

[MHM Cisco World]

Apologies 

advertised to it any case  <<- 

In bgp there are many case 

A- Not advertise 

B- Advertise not inject into bgp

C- advertise inject into bgp not inject into RIB.

I never mentioned it not advertise it mention it adverise and ignore' i.e. case ""B"".

Each one of above issue have different solution.

He can try run debug bgp update to check if it adverise or not.

MHM

[paul driver]

Hello @MHM Cisco World 

just don’t focus on bgp either the OP said routes are not being received on rtr1 either (eigrp) and as their OP cfg looks okay (apart from your next-hop-self) then something else is filtering the mutual redistribution 

[Flavio Miranda]

@beta_admin66 

 You this instead

Router EIGRP 100

 redistribute bgp 1000 metric 100 1 255 1 1500

[paul driver]

Hello

R1:
Router EIGRP 100
eigrp router-id 1.1.1.1

R2:
Router EIGRP 100
eigrp router-id 2.2.2.2

Router BGP 100
bgp router-id 2.2.2.2
bgp redistribute-internal
network 10.23.1.0 mask 255.255.255.0
neighbor 10.23.1.2  next-hop-self

R3:
Router BGP 100
bgp router-id  3.3.3.3

[David Ruess]

Hello,

Can we see the routing table of all the devices?

When redistributing routing ptotocols the router must see the routes from that routing protocol. For example. You say R1-R2 is an EIGRP neighborship, but is R1 sending any routes via EIGRP such as any loopback addresses? Asking because if just the link between R1 and R2 is advertised in EIGRP then R2 will still only see that link as directly connected and install it as such in the routing table, not from EIGRP so then when you redistribute EIGRP into BGP it doesn't have any EIGRP routes, so no routes are redistributed. Same goes for BGP and R2-R3.

-David