[c-nsp] BGP re-announcement question

[Arie Vayner (avayner)]

Pete,

I wrote that I am not sure your customer would always want you to send traffic down their link because there are scenarios where customers would buy backup links which they expect not to get traffic on unless some other primary link goes down...

So making the firm assumption might be wrong in all cases, and this is why the ability to control it (via communities as the easiest option or calls to the NOS as a worst case scenario) is critical.

I do agree that setting the local-pref for customers to higher than default is a good practice and should be implemented.

Arie

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Pete Templin
Sent: Thursday, August 1, 2013 6:02 AM
To: Adam Greene
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] BGP re-announcement question

On 7/29/13 4:06 PM, Arie Vayner (avayner) wrote:
> The best route is through your upstream (I guess), so you are not 
> advertising it back... You could increase the local-pref for routes 
> you receive from your customers as compared to routes you receive from 
> your upstreams. In this way you would always prefer the local path to 
> your customer (not sure they would like you to do that...)

+10000 on this.  They are your customer, so it's safe to presume that
they want you to carry their traffic (they send you a check every month in exchange for this service), and in turn you (might) send a check elsewhere to continue the process.  It's not an easy thing to roll out en masse, but I'd argue that it needs to be done.

I normally use 400 for customer routes, 300 for routes from peers (I've been known to use transit providers as peers; accept only their routes and their customer routes, and advertise out with no-export or their own 'peer' community), 200 for routes from transits.  One benefit is that an "unconfigured" router with LP=100 won't get any traffic, so it'll make the lack of proper configuration obvious.

As others suggested, a community to override this might be appreciated by your customers, if they have enough clue to use it. Be warned that since "everyone else" (or at least everyone else upstream of you) does this same sort of preference, so if they request a low LP in your network, they're going to want a low LP in subsequent networks until they get to the peered-only networks.

pt


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