[j-nsp] multiple bgp routing tables

[Peter Van Oene]

On Thu, Nov 6, 2008 at 8:52 AM, Ying Zhang <cynthia_dal at yahoo.ca> wrote:
> Just curious, if use "filter-based forwarding" with multiple bgp routing
> tables from multiple ISPs, in case ISP-1 peer is down, will the other ISPs
> become backup links for these prefixes used to destine to ISP-1?

JUNOS allows you to point one routing table at another, thus your
default route for route-table-isp1 and be route-table-isp2 such that
is isp1 dies, all traffic routes through ISP2.  This looks like
redundant source based routing essentially.  I've seen this
implemented with success a few places.

Pete



>
> Thanks.
> ----- Original Message ----- From: "Boyd, Benjamin R"
> <Benjamin.R.Boyd at windstream.com>
> To: <truman at suspicious.org>; "John T. Yocum" <john at fluidhosting.com>;
> <juniper-nsp-bounces at puck.nether.net>; <juniper-nsp at puck.nether.net>
> Sent: Wednesday, November 05, 2008 6:37 PM
> Subject: Re: [j-nsp] multiple bgp routing tables
>
>
>> >Use communities or prefix lists that restrict the
>>>
>>> advertisement of specific prefixes for each bgp group/peer.
>>>
>>> Local pref the received routes from the neighbours that you prefer ...
>>>
>>>
>>>
>>
>> I think the problem you'll find with preffing the routes from particular
>> neighbors is the fact that you don't want to limit by destination.  I
>> think he "prefers" all neighbors, but only wants the "special" blocks
>> he's advertising to his neighbors to only use those sessions as transit
>> regardless of destination.  For this he will need filter-based
>> forwarding (aka Source Based Routing).  I've done this in places and
>> this document really helped:
>>
>> http://cn.juniper.net/solutions/literature/white_papers/552003.pdf
>>
>> -Ben
>>
>>
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