03-13-2012 11:52 AM
Hello,
Right now we have InterAS MPLS Option C configured between 2 autonomous systems.
Now we need to add more bandwith and would like to add another interface between the two routers establishing a multihop session using loopbacks to load share traffic.
I know that IOS-XR does not automatically learn directly connected host routes so for the XR router to assign labels you'll need to configure a static host route to ensure MPLS forwarding to the neighboring AS.
This works with directly connected neighbors but when I try to enable the multihop session, the XR does not assign labels even configuring the staic host route.
Does anybody has a configuration like that working?
Thanks!!
Jose.
03-21-2012 06:34 PM
Hello Jose
There are basically two options in Option C L3VPN setup. I will discuss the first option for Multihop.
Following are the key points that distinguish the InterAS Option C from previous options.
1) External Multihop BGP address families are invoked between two different autonomous systems; however, these eBGP sessions are invoked between the route reflectors in each AS and not on the ASBR. The route reflector in each AS thus passes labeled ipv4 unicast VPN routes to the other AS. Note:- The route reflector in this case will have PE clients in the vpnv4 address family within that Autonomous System.
2) ASBRs facilitate the creation of InterAS LSP by providing labeled /32s for PE and Route Reflector loopback.
3) This option enhances scalability because ASBRs do not handle VPNv4 routes in fact this option gets rid of the extra L3VPN LFIB that is created as a result of option B . The LFIB size is minimal as we control the redistribution to the only 2 needed loopback addresses (remote ASBR and remote RR)
Sample config of the RR:
router bgp 102
address-family ipv4 unicast
!
address-family vpnv4 unicast
!
neighbor-group ibgp
remote-as 102
update-source Loopback0
address-family ipv4 unicast
route-reflector-client
!
address-family vpnv4 unicast
route-reflector-client
!
neighbor 192.168.253.3
remote-as 101
ebgp-multihop 255
description eBGP-RR-PEER-AS101
update-source Loopback0
address-family vpnv4 unicast
route-policy allow-all in
route-policy allow-all out
next-hop-unchanged
!
!
neighbor 192.168.254.1
use neighbor-group ibgp
!
neighbor 192.168.254.3
use neighbor-group ibgp
!
neighbor 192.168.254.4
use neighbor-group ibgp
On the PE router, the config will look something like this:
router bgp 102
address-family ipv4 unicast
redistribute ospf 1 metric 3333 route-policy interAS-optionc-out
allocate-label route-policy interAS-optionc-out
!
neighbor 65.10.20.1
remote-as 101
address-family ipv4 labeled-unicast
route-policy interAS-optionc-in in
route-policy interAS-optionc-out out
!
!
neighbor 192.168.254.2
remote-as 102
update-source Loopback0
address-family ipv4 unicast
!
router static
address-family ipv4 unicast
65.10.20.1/32 TenGigE0/0/0/1
192.0.2.0/24 Null0 tag 10
!
!
route-policy interAS-optionc-in
if destination in remote-RR-PE then
pass
else
drop
endif
end-policy
!
route-policy interAS-optionc-out
if destination in local-RR-PE then
pass
else
drop
endif
end-policy
!
prefix-set local-RR-PE
192.168.254.2/32,
192.168.253.6/32,
192.168.253.5/32
end-set
!
prefix-set remote-RR-PE
192.168.253.2/32,
192.168.253.3/32,
192.168.253.3/32
end-set
!
Just for your clarification, 192.168.253.0/24 is the Remote AS networks and 192.168.254.0/24 is the local AS networks.
Hope this clarifies your doubts.
Cheers ... !!!
Vinit
03-21-2012 08:07 PM
Hello Vinit
Thanks for your response but I think I didn't explain the problem correctly. What you explained is correct as a matter of fact, I do have the configuration exactly that way.
Actually my problem is I need to add more bandwidth between Autonomus Systems. When I try to add another TenGig interface between ASBRs and configure the IPv4 session as multihop (to loadshare between de two TenGig interfaces), the 12k XR router does not assign labels to the 7609 on the remote AS.
I will let you know if I find a solution.
Thanks for your help.
regards,
Jose.
03-21-2012 08:11 PM
Hello Jose,
Thanks for the prompt reply. Let me know if you are not able to get anything on it. I shall be able to help you fix the issue.
let me know if you need any help related to XR or any other issue related to your setup.
Regards
Vinit
03-21-2012 08:15 PM
Thanks Vinit!
I'll keep you posted.
best,
Jose
03-21-2012 10:46 PM
Hi ,
In Option-C, how many labels are assigned to prefixes & what are they?
Regards
Pradip Vaghela
03-21-2012 10:58 PM
Hello Pradip,
In Option C, there are two methods:
1) PE loopbacks of the other AS are advertised in local AS via IGP ROUTES (redistributed from eBGP)
In this method two labels will be used:
a) 1 for the VPN
b) 1 for the PE loopback (like regular MPLS-VPN)
2) PE loopbacks of other AS are advertised in local AS via iBGP ROUTES
In this method three labels used
a) 1 for the VPN
b) 1 for destination PE (next-hop)
c) 1 to get to the local ASBR
I am not mentioning about the local mpls ldp or TE labels (if present)
Hope this answers your question.
Regards
Vinit
03-21-2012 11:16 PM
gotcha
- Pradip
03-22-2012 10:10 AM
Jose
You may find some useful information about Inter-AS Option C Multipath Load Balance Options here (Page 17):
http://blog.uruhu.su/sites/default/files/Cisco_I-AS-MPLS.pdf
HOSTNAME ASBR
!
interface e0/0
ip address 168.192.0.2 255.255.255.252
mpls bgp forwarding
! Enable BGP forwarding on connecting interfaces
!
interface e2 /0
ip address 168.192.2.2 255.255.255.252
mpls bgp forwarding
!
router bgp 2
neighbor 10.10.10.10 remote-as 1
neighbor 10.10.10.10 disable-connected-check
neighbor 10.10.10.10 update-source Loopback0
!
!
address-family ipv4
neighbor 10.10.10.10 activate
neighbor 10.10.10.10 send-label
!
ip route 10.10.10.10 255.255.255 e0/0 168.192.0.1
ip route 10.10.10.10 255.255.255 e2/0 168.192.2.1
!
Configure /32 static routes to the eBGP neighbor loopback address
But they only talk about IOS, may be you can visit this site, to convert IOS commands to IOX
Kind regards
Gustavo
01-07-2016 07:36 AM
Hi Vinit
When I deploy the Option C (BGP ipv4+label) on XR, the VPNV4 routes can be learned by each router in two AS, beside the next-hops are reachable. But there is a problem with the Label assignments on CN-ASBR(XR).
sh cef vrf OAM 10.204.64.13
next hop 10.204.92.13 via 24004/0/21
next hop 10.0.0.2/32 Gi0/0/0/0 labels imposed {ImplNull 24007} ImplNull----issued place
sho bgp vpnv4 unicast
*> 10.204.64.13/32 10.204.92.13 0 65160 i
sho bgp vpnv4 unicast labels
*> 10.204.64.13/32 10.204.92.13 24007 nolabel
sho bgp ipv4 un label
*> 10.204.92.3/32 10.0.0.2 3 24002
I addressed this issue on ImplNull and don't know why the top label 3 can't be attached. Can you give me some suggestion on this troubleshooting?
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