[c-nsp] 3550 as a BGP Router

Adrian Chadd adrian at creative.net.au
Wed Sep 12 22:28:33 EDT 2007

On Wed, Sep 12, 2007, Jon Lewis wrote:

> >You could always try. That said, for like $200 could you pick up a 2610
> >or something similar off ebay as the route server and bypass the problem
> >entirely.
> How would you propose he connect a dozen ISPs to a 2610?
> I suspect the 3550 would work (EMI software required) as long as the 
> number of BGP routes is kept low (he mentioned <100 routes...if that's the 
> total for all peers combined, I don't see a problem).  The switch has the 
> advantage of plenty of ports (which can be configured as layer 3 ports) 
> capable of wire-rate...unlike the 2600 series.

Uhm, because you can use the 26xx as a route server; it'll pass eBGP
next-hop info as directly-connected if you don't use next-hop-self.
The 2610 won't see any traffic besides eBGP.

> I've done iBGP and eBGP on a 3550, though this was only 2-3 peers and a 
> handful of routes.  IIRC, the BGP command set on the 3550 is somewhat 
> stripped down...but I can't remember exactly which features I think were 
> missing.  I know from looking at the config, peer-groups, prefix-lists, 
> and route-maps are supported.

Cisco IOS Software, C3550 Software (C3550-IPSERVICESK9-M), Version 12.2(35)SE, RELEASE SOFTWARE (fc2)


blue-1#show ip bgp sum
BGP router identifier X, local AS number Y
BGP table version is 251406, main routing table version 251406
5582 network entries using 653094 bytes of memory
11159 path entries using 580268 bytes of memory
603/597 BGP path/bestpath attribute entries using 69948 bytes of memory
338 BGP AS-PATH entries using 8996 bytes of memory
249 BGP community entries using 7512 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
493 BGP filter-list cache entries using 5916 bytes of memory
BGP using 1325734 total bytes of memory
1 received paths for inbound soft reconfiguration
BGP activity 38926/33344 prefixes, 211839/200680 paths, scan interval 60 secs

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd  4  7606  189755  142009   251406    0    0 9w2d         5577  4  7606  188920  142012   251406    0    0 9w1d         5574

(and other internal peers go here.)

So I know what the 3550'll do if you need it speaking BGP/OSPF.
I've also seen its failure modes (max CPU == suddenly your FIB isn't
updated as quickly as you'd like; and BGP does chew CPU.)

Fine, if 2610 tops out at 64meg then just buy a slightly bigger 2600.
If its an IX situation I'd definitely say "run a seperate route server
and leave the 3550 to handle switching and QoS." It'd certainly make
upgrading easier.

Skeeve - consider eventually buying two route servers, so you can upgrade
one without breaking connectivity.


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