[Xorp-users] Problems with IBGP
Alejandro Berna
alejandro.berna at i2cat.net
Fri May 8 05:56:19 PDT 2009
Hi again, as I've seen the bgp routes and my testbed map are not good
shown in my last mail. I try to fix this:
The bgp route table for Router 2 is:
Prefix Nexthop Peer AS Path
*> 10.1.10.0/24 10.1.10.2 0.0.0.0 i
*> 10.9.7.0/24 10.129.0.3 0.0.0.0 i
*> 10.10.10.0/24 10.10.10.10 0.0.0.0 i
*> 10.129.0.0/24 10.129.0.2 0.0.0.0 i
*> 10.3.7.0/24 10.10.10.20 10.10.10.20 65000 i
*> 10.3.9.0/24 10.10.10.20 10.10.10.20 65000 i
*> 10.9.9.0/24 10.10.10.20 10.10.10.20 65000 i
* 10.10.10.0/24 10.10.10.20 10.10.10.20 65000 i
And the bgp route table for Router 1 is:
Prefix Nexthop Peer AS Path
*> 10.1.10.0/24 10.1.10.2 10.10.10.10 i
* 10.3.7.0/24 10.10.10.20 10.10.10.10 65000 i
* 10.3.9.0/24 10.10.10.20 10.10.10.10 65000 i
*> 10.9.7.0/24 10.129.0.2 10.10.10.10 i
* 10.9.9.0/24 10.10.10.20 10.10.10.10 65000 i
* 10.10.10.0/24 10.10.10.10 10.10.10.10 i
*> 10.129.0.0/24 10.129.0.2 10.10.10.10 i
Also I attach my testbed picture, sorry for the spamming and the
inconvenients,
Alejandro
Alejandro Berna escribió:
> Hi all,
>
> I am trying to configure two ASs (65002 and 65000). Every AS for
> internal routing has configured OSPFv4 and it works properly. Between
> the two ASBR routers I have configured EBGP exporting the OSPF routes to
> each one. The peer interfaces of the EBGP are not configured in the
> internal OSPFv4 protocol of every AS. The two ASBR routers learn all the
> networks (the external and the internals) and know how to reach to every
> one. Now I need to send the networks learned thanks to EBGP to the rest
> of the internal routers of each AS. I need to do it with IBGP (for my
> objectives I cannot import these routes to the OSPF database). I
> configure IBGP inside every AS but I find a problem; they learn the
> routes but the next-hop of every external AS network is the peer
> interface of the EBGP (these interfaces are not in the OSPF database
> therefore the internal routers doesn't know how to reach them). I've
> tried using loopback address for the IBGP peers but with this solution
> the internal routers doesn't learn any external network. This is my testbed:
>
>
>
>
> The two peer interfaces for EBGP are Router 2 eth1 and Router 5 eth3. As
> I commented before these 2 interfaces are not included in the internal
> AS OSPF configuration. In order to expose my doubt I show Router 1 and
> Router 2 configuration as they were the only 2 routers that have IBGP
> configuration (Router 3 excluded for the IBGP configuration):
>
> The configuration file for Router 2 is:
>
> interfaces {
> interface eth1 {
> vif eth1 {
> address 10.10.10.10{
> prefix-length: 24
> disable: false
> }
> }
> }
> interface eth2 {
> vif eth2 {
> address 10.129.0.2 {
> prefix-length: 24
> disable: false
> }
> }
> }
> interface eth3 {
> vif eth3 {
> address 10.1.10.2 {
> prefix-length: 24
> disable: false
> }
> }
> }
> }
>
> fea {
> unicast-forwarding4 {
> disable: false
> }
> }
>
> policy {
> policy-statement export-routes {
> term 100 {
> from {
> protocol: "connected"
> }
> }
> term 101 {
> from {
> protocol: "ospf4"
> }
> }
> term 102 {
> from {
> protocol: "bgp"
> }
> }
> }
> }
>
> protocols {
> ospf4 {
> router-id: 192.168.0.2
>
> area 0.0.0.0 {
>
> interface eth2 {
> vif eth2 {
> address 10.129.0.2 {
>
> }
> }
> }
> interface eth3 {
> vif eth3 {
> address 10.1.10.2 {
> }
> }
> }
> }
> }
> bgp {
> bgp-id: 10.10.10.10
> local-as: 65002
> export: "export-routes"
> peer 10.10.10.20 {
> local-ip: 10.10.10.10
> as: 65000
> next-hop: 10.10.10.10
> }
> peer 10.129.0.3 {
> local-ip: 10.129.0.2
> as: 65002
> next-hop: 10.129.0.2
> }
> }
> }
>
>
> And the configuration file for Router 1 is:
>
>
> interfaces {
> interface eth1 {
> vif eth1 {
> address 10.129.0.3 {
> prefix-length: 24
> disable: false
> }
> }
> }
> interface eth2 {
> vif eth2 {
> address 10.9.7.3 {
> prefix-length: 24
> disable: false
> }
> }
> }
> }
>
> fea {
> unicast-forwarding4 {
> disable: false
> }
> }
>
> protocols {
> ospf4 {
> router-id: 192.168.0.1
> area 0.0.0.1 {
> interface eth1 {
> vif eth1 {
> address 10.129.0.3 {
> }
> }
> }
> interface eth2 {
> vif eth2 {
> address 10.9.7.3 {
> }
> }
> }
> }
> }
> bgp {
> bgp-id: 10.129.0.3
> local-as: 65002
> peer 10.129.0.2 {
> local-ip: 10.129.0.3
> as: 65002
> next-hop: 10.129.0.3
> }
> }
> }
>
> The bgp route table for Router 2 is:
>
> Prefix Nexthop
> Peer AS Path
> *> 10.1.10.0/24 10.1.10.2
> 0.0.0.0 i
> *> 10.9.7.0/24 10.129.0.3
> 0.0.0.0 i
> *> 10.10.10.0/24 10.10.10.10
> 0.0.0.0 i
> *> 10.129.0.0/24 10.129.0.2
> 0.0.0.0 i
> *> 10.3.7.0/24 10.10.10.20
> 10.10.10.20 65000 i
> *> 10.3.9.0/24 10.10.10.20
> 10.10.10.20 65000 i
> *> 10.9.9.0/24 10.10.10.20
> 10.10.10.20 65000 i
> * 10.10.10.0/24 10.10.10.20
> 10.10.10.20 65000 i
>
> And the bgp route table for Router 1 is:
>
>
> Prefix Nexthop
> Peer AS Path
> *> 10.1.10.0/24 10.1.10.2
> 10.10.10.10 i
> * 10.3.7.0/24 10.10.10.20
> 10.10.10.10 65000 i
> * 10.3.9.0/24 10.10.10.20
> 10.10.10.10 65000 i
> *> 10.9.7.0/24 10.129.0.2
> 10.10.10.10 i
> * 10.9.9.0/24 10.10.10.20
> 10.10.10.10 65000 i
> * 10.10.10.0/24 10.10.10.10
> 10.10.10.10 i
> *> 10.129.0.0/24 10.129.0.2
> 10.10.10.10 i
>
>
> As I commented Router 2 is able to reach any network of both ASs. Router
> 1 is only able to reach the networks inside the AS because it doesn't
> know how to reach 10.10.10.0/24 network. How can I fix this? I specified
> the IBGP next hop for Router 1 as the interface 10.129.0.2 but in the
> bgp route it appears 10.10.10.20, what am I doing wrong? I hope somebody
> can help me, thanks a lot,
>
>
> Alejandro Berna
>
>
>
>
> _______________________________________________
> Xorp-users mailing list
> Xorp-users at xorp.org
> http://mailman.ICSI.Berkeley.EDU/mailman/listinfo/xorp-users
>
>
--
Alejandro Berna Juan
Network Technologies Cluster (CTX)
Fundació i2Cat, Internet i Innovació Digital a Catalunya
C/ Gran Capità 2 - 4, Nexus I building, 2nd floor, office 203
08034 Barcelona, Catalonia, Spain
P: +34 93 553 2522
F: +34 93 553 2520
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