[c-nsp] BGP Multi-homing

Ramesh Karki rameshkarki at gmail.com
Wed Apr 14 04:02:29 EDT 2010


Hi Bob,

I suggest you to receive full bgp routes from both your provider if your
router is capable to handle it. so that you can tune your outgoing traffic
as required. As you are receiving only default route from primary provider
and full bgp table from secondary, then it will be complicated to tune
outgoing traffic towards primary provider. Coz default route will be check
at last,if there are no specific route for the traffic on the table
Here in your scenario what you can do is: received only local route and
default route from secondary provider and increase local preference received
default route from primary ISP, so the traffic for the local route (must
specific) will go via secondary and rest to the primary.

For return traffic you can announce your prefixes prepending to secondary
provider and default to primary provider. I think this will help to achieve
your requirement.

Thank you,
Ramesh

On Tue, Apr 13, 2010 at 5:29 PM, Tim Vollebregt
<t.vollebregt at leaseweb.com>wrote:

> Hi Bob,
>
> There are a lot of configuration options to do this.
>
> A simple solution for this, hereby I assume that your secondary neighbor is
> accepting (default) bgp communities.
>
> Primary neighbor (default route): 1.1.1.1 AS10
> Secondary neighbor (full table): 2.2.2.2 AS20
> Local AS: AS30
> Local prefixes: 3.3.3.0/24 and 4.4.4.0/24
>
> Create as-path acl:
> ip as-path access-list 2 permit _20$
>
> Create no-export access-list (specify your local/customer prefixes here):
>
> ip prefix-list no-export seq 1 permit 3.3.3.0/24
> ip prefix-list no-export seq 2 permit 4.4.4.0/24
> ip prefix-list no-export seq 10 deny 0.0.0.0/0 le 32
>
> Create route-maps:
> --inbound--
> route-map secondary-in permit 5
> match as-path 2
> set localpref 105
> route-map secondary-in permit 10
> set localpref 80
>
> --outbound--
> route-map secondary-out permit 5
> match ip address prefix-list no-export
> set community no-export additive
> You don't have to change anything in the configuration of your primary
> neighbor, only put the in and outbound route-maps on the bgp session:
>
> Router bgp 30
> Address-family ipv4
> Neighbor 2.2.2.2 send-community
> Neighbor 2.2.2.2 route-map secondary-in in
> Neighbor 2.2.2.2 route-map secondary-out out
>
> Please make sure you also have an normal outbound prefix list on the
> session.
>
> If your secondary neighbor has a lot of 'local' routes which you want to
> send traffic to, but these routes are not originated from AS20. You should
> ask them if they can specify a customer bgp community. Afterwards you can
> match that community in the inbound route-map and set a localpref of 100+ to
> it.
>
> Regards,
>
> Tim
>
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:
> cisco-nsp-bounces at puck.nether.net] On Behalf Of bobby hajhassan
> Sent: dinsdag, 13 april, 2010 10:01
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] BGP Multi-homing
>
>
> Turning up a backup BGP session with a secondary provider. Currently
> accepting a default route from my primary provider and will have full table
> from secondary. Would like to continue to have the primary provider as the
> preferred inbound/outbound path once i've turned up the secondary session. I
> would however like to prefer the local only routes from my secondary
> provider and have all other routes preferred through my primary. Config
> templete would be great...any help is appreciated.
>
> Thanks
> Bob
>
>
>
>
>
>
> _________________________________________________________________
> Hotmail has tools for the New Busy. Search, chat and e-mail from your
> inbox.
>
> http://www.windowslive.com/campaign/thenewbusy?ocid=PID28326::T:WLMTAGL:ON:WL:en-US:WM_HMP:042010_1
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>


More information about the cisco-nsp mailing list