Cisco 7600 (7609) as a core BGP router.

Jon Lewis jlewis at
Fri Jul 17 23:19:45 UTC 2009

On Fri, 17 Jul 2009, Brad Fleming wrote:

> We don't run very much Cisco gear (none of their larger, hardware stuff) but 
> I have a couple questions for the Cisco gurus out there...
> According to this page:
> The Cisco WS-SUP720-3BXL can hold "1,000,000 (IPv4); 500,000 (IPv6)" route 
> entries.
> 1) Does that mean a) The card can hold 1m IPv4 routes --OR-- 500K IPv6 routes 
> or b) 1m IPv4 routes --AND-- 500K IPv6 routes?

OR.  Or you can have 524288 v4 and 262144 v6 routes...or you can move the 
split around.  I chose:

L3 Forwarding Resources
              FIB TCAM usage:                     Total        Used       %Used
                   72 bits (IPv4, MPLS, EoM)     622592      289791         47%
                  144 bits (IP mcast, IPv6)      212992           8          1%

Adjusting the split requires a reboot.

> 2) I'm assuming MPLS cuts into the number somewhere but could anyone explain 
> it briefly?

I think the above actually does.

> 3) Do ACLs use some of these resources or do they get their own slice of 
> memory?

Don't think so.

I did a blog entry about this a while back.

> That page also reports "up to 40 Gbps per slot of switching capacity; 720 
> Gbps aggregate bandwidth".
> Is the 40Gbps per slot an aggregate or full-duplex value?

AFAIK, cisco always reports these things as input+output = bandwidth.  It 
makes the numbers more impressive.

We've been using 6509s as BGP routers for years and they've generaly been 
rock stable.

  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
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