[c-nsp] L3 Switch as a BGP Gateway

Tue Jun 28 14:16:57 EDT 2011

If pulling default route only from 3 or 4  providers,, some minor weighting is doable..
I saw a 3750X with 3 providers, 10 /24s behind it... each with a different community string.... and each pulling a default route and a handful(10 or so /20) of first upstream blocks...

It seemed to do fine....
Did not like it... show commands were rather slow...
So your mileage may vary...

Jim

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Murphy, Jay, DOH
Sent: Tuesday, June 28, 2011 1:37 PM
To: farisy at gmail.com; Jay Hennigan; cisco-nsp-bounces at puck.nether.net
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] L3 Switch as a BGP Gateway

Yes, without full feeds, and allowing the provider to filter their routes, and you route statically to your provider. For Metro optical Ethernet, it is a deployable solution. Current BGP routes, roughly 350,000+, in addition to internal routes and what have you... that said, a BGP speaker used only for a network with a single point of entry to the Internet may have a much smaller routing table size--thus the modest requirements needed for RAM and CPU--than a multi-homed network. Even simple multi-homing can have modest routing table size.

~Jay Murphy
Sr. IP Network Specialist
NM State Government

IT Services Division
PSB – IP Network Management Center
Santa Fé, New México 87505 

"We move the information that moves your world." 
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-----Original Message-----
From: farisy at gmail.com [mailto:farisy at gmail.com]
Sent: Monday, June 27, 2011 7:24 PM
To: Jay Hennigan; cisco-nsp-bounces at puck.nether.net; Murphy, Jay, DOH
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] L3 Switch as a BGP Gateway

Dear Jay,
As far as I know, IPv4 BGP entry is more than 300k entry, I don't think it will suite with a 3750.
Please refer to routing handling from its datasheet. 
I'm agree with the other, if you would run default gateway for multihomed upstream, 3750 will do.
Hope it help.

Rgrds,
-farisy-

-----Original Message-----
From: Jay Hennigan <jay at west.net>
Sender: cisco-nsp-bounces at puck.nether.net
Date: Mon, 27 Jun 2011 13:44:07
To: Murphy, Jay, DOH<Jay.Murphy at state.nm.us>
Cc: cisco-nsp at puck.nether.net<cisco-nsp at puck.nether.net>
Subject: Re: [c-nsp] L3 Switch as a BGP Gateway

On 6/27/11 1:30 PM, Murphy, Jay, DOH wrote:
> How about when you stack them as a logical switch. Couldn't one leverage the memory and processing of the stacking?

If you're taking just a default eBGP route from each external neighbor and using multi-homing as a primary/failover, you can get away with it.
 "Multi-homed BGP gateway" in your original post implies taking at least a partial table from a diversity of transit providers and/or peers, and these switches just aren't capable of dealing with anywhere near that many routes.

> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net 
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Jay Hennigan
> Sent: Monday, June 27, 2011 1:11 PM
> To: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] L3 Switch as a BGP Gateway
> 
> On 6/27/11 11:59 AM, Jason Greenberg wrote:
>> Can someone advise me as to why a 3750 L3 Switch (Metro Model) wouldn't outperform a 7300 series router as a multi-homed BGP gateway?  ISRs and Enterprise class routers are still quite a bit more expensive than the L3 Switches, but I'm starting to not understand why.   I understand that L3 switches are less feature rich on the routing end, but suppose that our ASAs are doing most of the complicated filtering.    I know it doesn't sound "right" to have a 3750G used in this manner, but I am having a hard time finding any real reason why not to do it.
> 
> The memory and number of routes are far too small to use these as a 
> border router.  Generally adequate for iBGP to inject customer routes 
> into your network but way too little for an Internet-facing border.

--
Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net Impulse Internet Service  -  http://www.impulse.net/ Your local telephone and internet company - 805 884-6323 - WB6RDV _______________________________________________
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