bgp to mpls cloud problem with route advertisements

[George Wolf]

I run bgp with 2 links to a provider and it's an MPLS link to them.  I'm prepending routes to certain local subnets so subnet A will be preferred on link 1 and subnet B will be preferred on link 2.  I use route maps and prepend our AS so that subnet A and B aren't preferred on the links but if a link goes down they will route.  I wont list out everything as I know you guys will follow here (nothing complicated).  I'm using XO communications as my provider.  I don't think the prepend works with them, should this work? 

neighbor 1.1.1.1  remote-as 2828
 neighbor 1.1.1.1 route-map primary_voice_path in
 neighbor 1.1.1.1 route-map VOICE_PREFER out
 neighbor 2.2.2.2 remote-as 2828
 neighbor 2.2.2.2 route-map primary_data_path in
 neighbor 2.2.2.2 route-map DATA_PREFER out

example for voice route map is below- data is same but switched (you get the idea)

route-map VOICE_PREFER permit 10
 match ip address DATA
 set as-path prepend 64520 64520 64520 64520
!
route-map VOICE_PREFER permit 20
 match ip address VOICE

[Nagendra Kumar Nainar]

George,

What behavior are you seeing?. Do you see all traffic from provider is using one link and the otehr link is used only if primary link is down?.

If the local preference (or weight) is configured to higher on 1.1.1.1 and lower on 2.2.2.2, it might result in preferring the one with higher LP.

-Nagendra

[George Wolf]

Hi Nagendra, local pref is only for how I route to the backbone.... I'm good there... where I'm asking and having the problem is having the backbone prefer route a on one link and route b on another.  That is why im prepending but it looks like that doesn't work as when I trace from other routers in that mpls cloud I go all over one link so I'm assuming even though im prepending the backbone isn't caring.

So the question is in private mpls backbones like xo and att is what I'm doing correct?  I'm not sure how else to tell the backbone to prefer route a over one line and route b over another...

I have no visibility to the PE router as I don't control that

any help appreciated,

George

[Nagendra Kumar Nainar]

Hi George,

where I'm asking and having the problem is having the backbone prefer route a on one link and route b on another.  That is why im prepending but it looks like that doesn't work as when I trace from other routers in that mpls cloud I go all over one link so I'm assuming even though im prepending the backbone isn't caring.

<Nagendra> Right and that is what my understanding when I answered the previous one :). You are using AS prepend so that your provider can choose the link that you want to for inbound traffic to your AS. But if the provider BGP routers are configured with weight or local preference, it will choose the best path based on the prvider configured weight or LP and your AS prepend may not help to influence the inbound traffic

-Nagendra

[George Wolf]

 I have multiple sites and they all act similar, I wouldn't think the provider would play with weight and local pref for all of them.