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Default route propagation in BGP

I have 3 routers in the same BGP cloud. R1 advertises a default route in BGP to PE1, and as such PE1 has a default route in the table for the VRF in question. I can see this on PE1 if i issue sh ip route vrf <vrf>

R1 >> PE1 >> PE2

This is not true of PE2, all VRF routes are present but not the default. if i issue the command 'show ip bgp vpnv4 all'i can see the default under the VRF.

though if i issue sh ip bgp vpnv4 vrf <VRF> command i cannot see the default route?

How can i get this route to propagate to PE2? it seems it is getting to PE2, but not going into the routing table. I have no filtering enabled.

Thanks.

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: Default route propagation in BGP

Daniel,

In this context, the FW is used as a CE device and should be running eBGP with PE1.

The FW doesn't share a common IGP with PE1 and PE2, it should therefore be in its own AS (most likely private).

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
5 REPLIES
Cisco Employee

Re: Default route propagation in BGP

Daniel,

You should definitely be able to propagate the default route via VPNv4. Can you do a "show ip bgp v a 0.0.0.0" on PE1.

Regards,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: Default route propagation in BGP

PE1

sh ip bgp vpnv4 all

Route Distinguisher: 1:100 (default for vrf TEST)

*>i0.0.0.0 172.16.1.1 0 100 0 ?

sh ip route vrf TEST

B* 0.0.0.0/0 [200/0] via 172.16.1.1, 00:04:00

PE2

sh ip bgp vpnv4 all

Route Distinguisher: 1:100 (default for vrf TEST)

* i0.0.0.0 172.16.1.1 0 100 0 ?

sh ip route vrf TEST on PE2 shows that route table does not contain the default.

Cisco Employee

Re: Default route propagation in BGP

Daniel,

The route is not valid on PE2 probably because the next hop (172.16.1.1) is unreachable. A "show ip bgp v a 0.0.0.0" on PE2 should confirm this.

Is R1 used as a CE? If so, I would just like to point out that using iBGP between the PE and the CE is an unsupported configuration. eBGP is normally used between the PE and CE.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: Default route propagation in BGP

R1 is a VRF aware firewall. This is in the same AS as PE1 and PE2. I would have thought it should be in the same AS, is that incorrect?

Cisco Employee

Re: Default route propagation in BGP

Daniel,

In this context, the FW is used as a CE device and should be running eBGP with PE1.

The FW doesn't share a common IGP with PE1 and PE2, it should therefore be in its own AS (most likely private).

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
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