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Infuencing BGP routes learned via EIGRP

Unanswered Question
Nov 5th, 2014
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I am hoping to get some direction on a routing design.

 

I have a data center connected to two collocations via DWDM. The three locations are within in the same EIGRP AS 10, EIGRP is the only routing protocol running between the data center and the two collocations. Each collocation is running BGP with it's own AS (ie collo A is BGP 1 and collo B is BGP 2) and also EIGRP 10. Each collo has a Verizon MPLS circuit and a XO MPLS circuit, the MPLS routers and core at each collo have iBGP and EIGRP running between them.

 

Collo A is the primary collo for the collo A networks, data center networks, outbound internet and a backup for collo B networks. It is also the primary transit point between the Verizon and XO MPLS networks (XO is used as a backup for critical offices)

Collo B is the primary collo for the collo B networks and backup for the data center networks, outbound internet and collo A networks. It is also the backup transit point between the Verizon and XO MPLS networks.

 

Here is where I am running into an issue. I will use collo B as the example.

 

I want to group the traffic in my outbound bgp route map separately so that I can take different actions on each type of traffic (collo A, collo B, data center, etc) and change it at any point with minimal configuration for any given traffic type.

 

In collo B I want to prepend collo A networks and data center networks but I do not want to use a prefix-list, especially for the data center because that would become too cumbersome with the amount of networks I would need in the list.

 

My original plan was to tag collo A eigrp routes with a tag of 1, tag data center internal eigrp routes with 10 and data center external eigrp routes with 20. Then on the collo B core redistribute eigrp into bgp and match internal and tag 20. Then on the routers have a route map statement for data center traffic matching tag 10 and 20 and prepend the routes, then do the same with a route-map statement for the collo A routes.

 

However matching a tag on an outbound BGP map is not supported. So I am looking for another way to accomplish this. My thought was to use a community and on the routers have an inbound BGP map on the core switch peer matching the tags and setting a BGP community and then on the outbound map match that community and set the prepend.

 

router bgp 9100
 bgp log-neighbor-changes
 neighbor 10.2.0.238 remote-as 9100
 neighbor 10.2.0.254 remote-as 9100
 neighbor 1.1.1.1 remote-as 65000
 neighbor 1.1.1.1 fall-over bfd
 !
 address-family ipv4
  aggregate-address 10.2.0.0 255.255.128.0 summary-only
  neighbor 10.2.0.238 activate
  neighbor 10.2.0.238 next-hop-self
  neighbor 10.2.0.238 soft-reconfiguration inbound
  neighbor 10.2.0.238 route-map SET_COM in
  neighbor 10.2.0.254 activate
  neighbor 10.2.0.254 next-hop-self
  neighbor 10.2.0.254 soft-reconfiguration inbound
  neighbor 10.2.0.254 route-map SET_COM in
  neighbor 1.1.1.1 activate
  neighbor 1.1.1.1 soft-reconfiguration inbound
  neighbor 1.1.1.1 route-map BGP_IN in
  neighbor 1.1.1.1 route-map BGP_OUT out
 exit-address-family
!
route-map SET_COM permit 5
 description *** Set Community ***
 match tag 10
 set community 65000:3
!
route-map SET_COM permit 10
 description *** Set Community ***
 match tag 20
 set community 65000:3
!
route-map BGP_OUT permit 50
 description *** Data Center Routes to Allow and Actions ***
 match community 65000:3

set as-prepend 9100 9100 9100
 

Is this a workable solution? Can the community be anything as long as it is not something that matches a community within the ISP? Attached is a diagram as well.

 

Kevin

 

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rais Wed, 11/05/2014 - 09:40
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What are you trying to achieve? Just a flexibility to apply policies based upon communities?

Is your Data Center running iBGP? If so you can add community right when you redistribute routes from EIGRP to BGP.

Also community is an optional attribute for ISP to carry and transport it across. Most likely they will be carried as is within your VPN but not surely from Vz to XO.

HTH.

kmelchior Wed, 11/05/2014 - 13:05
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Yes, I am trying to achieve flexibility applied policies and actions based upon a prefix or list pf prefixes without using a prefix-list to do so.

 

The data center will be all EIGRP once this project is complete, so all connectivity between the DC and collo's is EIGRP so the community would have to be set in the collo.

rais Fri, 11/07/2014 - 06:35
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I don't understand your condition for not using prefix-lists. That seems to be the most appropriate criteria supported in route-maps.

There is another match-criteria for metric, but it could be cumbersome to use. You can also check match-criteria on route-source.

HTH.

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