I am looking at some guidance on implementing route preference using BGP communities in our WAN network. Our service provider provided MPLS network spans the entire globe. I spoke to our service provider on influencing default route selection based on regions. For example countries in AsiaPac should prefer Singapore and stuff like that.
Our service provider came back to me and said that this can be implemented as he has made the community attribute to be transparent throught the network. My question is even if he has done that how do I proceed. Does anyone have some links/docs on communities implementation?
Communities are somewhat arbitrary numbers, with the exception of 4 standard communities (no-export, no-advertise, internet, local-as), and they're used for routing decisions. If the provider has assigned you a community to send to them, let's use 555:100 for example, they are expecting you to send this community with your routes. You can do this with a route-map applied to the neighbor:
route-map Community permit 10
set community 555:100
router bgp 1
neighbor 22.214.171.124 route-map Community out
neighbor 126.96.36.199 send-community
The above would set 555:100 on all of your routes. If you needed to set a community for a subset of routes, you'd change the route-map to match on a prefix list and then set the community that way:
ip prefix-list Singapore permit 192.168.1.0/24
ip prefix-list Brazil permit 192.168.2.0/24
ip prefix-list US permit 192.168.3.0/24
route-map Community permit 10
match ip address prefix Singapore
set community 100:200
route-map Community permit 20
match ip address prefix Brazil
set community 200:200
route-map Community permit 30
match ip address prefix US
set community 300:200
and the BGP configuration is the same. The provider on the other side would be looking for any routes that have these communities attached and they'd make routing decisions based on them.
Okay, their telling you that they're not going to strip them from your routes. That would mean that you would need to match on your communities on the other side and then make routing decisions based on whatever community you were matching on.
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
I dealt with a similar situation several years ago. Used community values to define a "virtual" AS topology, i.e. each site would tag its outbound routes with a community denoting it's virtual AS. On received routes, examined received community and prepended original AS by virtual AS hops.
Perhaps there is some aspect of your situation and your question that I do not understand correctly. But it seems to me that you have a fairly simple issue and I do not see where communities are needed.
If I am understanding correctly you have multiple remote sites. Each remote site has a Customer Edge Router (CE) which connects to the Provider Edge Router (PE). The PE will advertise a default route to the CE. The CE will use the default route to send its outbound traffic to its connected PE. Once the traffic is in the provider clould you no longer are making choices about how it will be forwarded.
So where would communities enter into this? If I have misunderstood something then please clarify.
Question We run asr9001 with XR 6.1.3, and we have a very long delay to
login w/ SSH 1 or 2 to the device compare to IOS device. After
investigation, the there is 1s delay between the client KEXDH_INIT and
the server (XR) KEXDH_REPLY. After debug ssh serv...
Introduction The purpose of this document is to demonstrate the Open
Shortest Path First (OSPF) behavior when the V-bit (Virtual-link bit) is
present in a non-backbone area. The V-bit is signaled in Type-1 LSA only
if the router is the endpoint of one or ...
Hi, I am seeing quite a few issues with patch install and wanted to
share my experience and workaround to this. Login to admin via CLI, then
access root with the “shell” command Issue “df –h” and you’ll probably
see the following directory full or nearly ...