04-19-2013 01:36 PM
I have a small setup with two IOS XRs and two IOS routers
I will be unable to test this but need some command reference.
(IOS)R1----->R2(XR)-------R3(XR)<-------R4(IOS)
R2 and R3 are in AS 1 and has vrf named vrf_cu
R1 and R4 are in AS 2
My Igp is configured
I have setup LDP neighbor relation ship between R2 and R3
There is a vpnv4 neighbor relation ship between them
Now My PE to CE protocol is BGP
R1 R2 R3 and R4 has their loopback 1s and R2 and R3 have them in vrf_cu
In R2
Route-policy PASS
pass
end-policy
router bgp 1
mpls activate
vrf vrf_cu
address-family ipv4 unicast
neighbor (R1's directly connected interface)
remote-as 2
redistribute connected
address-family ipv4 labeled unicast
route-policy PASS in
route-policy PASS out
as_override (This is because I have the same as at R4)
end
commit
Static route
add-ipv4 uni
R1's interface and outgoing interface of R2
exit
R1
router bgp 2
no bgp default-ipv4-unicast
neighbor (R2's interface) remote-as 1
add ipv4 uni
neighbor (neighbor ip) activate
neighbor (neighbor ip) send-community both
In the same way at R3 and R4. Now my question is why are we using address-family ipv4 labeled unicast for the commands shown in their?.
Regards
Thanveer
"Everybody is genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is a stupid."
Solved! Go to Solution.
04-19-2013 02:27 PM
well, the route-policy in and out are required for eBGP. In this scenario, the AF vpnv4 unicast would be configured for the iBGP session between PEs (R2 and R3), so no need for the route-policy.
The as-override, on the other hand, would be configured for a specific neighbor under the VRF section of the BGP configuration:
router bgp 100
vrf vpn1
rd 100:1
address-family ipv4 unicast
!
neighbor 10.0.0.1
remote-as 200
address-family ipv4 unicast
as-override
route-policy pass-all in
route-policy pass-all out
!
Hope this helps
04-20-2013 12:23 PM
Hi Thanveer,
That is correct and it is due to the fact that IOS-XR (and IOS as well) uses the same RIB for both labeled and unlabeled IPv4 prefixes.
Regards
04-19-2013 01:44 PM
Hi Thanveer,
If I understand your question, you want to do intra-AS not inter-AS, right? If so, AF ipv4 labeled unicast is not required in this scenario. It would in case you wanted to do inter-AS (option C). In your scenario, you need to use AF vpnv4 unicast between r2 and r3.
Hope this helps
04-19-2013 02:08 PM
Hello Harold,
Ok
Do you mean to say route-policy PASS in and PASS out should be in vpnv4 uni AF
As I have same AS no at R1 and R4 I need to use as-override command where should I type it?
I understand I also can use allow-as-in but Please clarify my doubt.
Thanks in Advance
Thanveer
04-19-2013 02:27 PM
well, the route-policy in and out are required for eBGP. In this scenario, the AF vpnv4 unicast would be configured for the iBGP session between PEs (R2 and R3), so no need for the route-policy.
The as-override, on the other hand, would be configured for a specific neighbor under the VRF section of the BGP configuration:
router bgp 100
vrf vpn1
rd 100:1
address-family ipv4 unicast
!
neighbor 10.0.0.1
remote-as 200
address-family ipv4 unicast
as-override
route-policy pass-all in
route-policy pass-all out
!
Hope this helps
04-19-2013 02:30 PM
Thanks Harold,
Today My day Is Good!!!
Regards
Thanveer
"Everybody is genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is a stupid."
04-19-2013 02:43 PM
A small question again,
if in inter as vpnv4 (OPTION C) if I donot have same AS no on the otherside then I would not require as-override command right?
only I should put route-policy PASS in and out.
like
address-family ipv4 unicast
rd 1:1
neighbor (R1's directly connected interface)
remote-as 2
as_override (This is because I have the same as at R4)
redistribute connected
route-policy PASS in
route-policy PASS out
address-family ipv4 labeled unicast
route-policy PASS in
route-policy PASS out
send-extended-community-ebgp
end
commit
Am I correct?
Regards
Thanveer
"Everybody is genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is a stupid."
04-19-2013 03:11 PM
InterAS means that you have two or more service providers, each with its own ASN, collaborating to offer MPLS services.
The as-override command is used on a eBGP session to the CE, in a case where multiple CEs that are part of the same VPN share the same ASN. This is true regardless you are in an intra or inter AS scenario. In the above scenario, you would indeed need as-override on the eBGP sessions to R1 and the one to R4.
The route-policy in and out are always needed on an eBGP session, whether it is AF vpnv4, ipv4 labeled unicast or any other for that matter.
Hope this helps
04-19-2013 03:19 PM
thanx Harold.
Regards
Thanveer
"Everybody is genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is a stupid."
04-20-2013 12:16 PM
Hello Harold,
I found this today at http://ieoc.com/forums/p/22920/179608.aspx
In IOS XR, DO NOT turn on both the unlabelled ipv4 unicast and the labelled-unicast for the same peer if you need the routes to have labels, the unlabelled configuration will overwrite the labelled and you will not have a labelled path. Only activate that neighbor under address-family ipv4 labelled-unicast.
Regards
Thanveer
"Everybody is genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is a stupid."
04-20-2013 12:23 PM
Hi Thanveer,
That is correct and it is due to the fact that IOS-XR (and IOS as well) uses the same RIB for both labeled and unlabeled IPv4 prefixes.
Regards
04-20-2013 12:34 PM
Thanks Harold.
Regards
Thanveer
"Everybody is genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is a stupid."
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