Cisco 7600 (7609) as a core BGP router.

Richard A Steenbergen ras at
Fri Jul 17 23:20:03 UTC 2009

On Fri, Jul 17, 2009 at 06:07:26PM -0500, 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?
> 2) I'm assuming MPLS cuts into the number somewhere but could anyone  
> explain it briefly?
> 3) Do ACLs use some of these resources or do they get their own slice  
> of memory?

The total size of the TCAM for forwardinging lookups is 9MB. IPv4 and
MPLS routes consume 72 bits per entry, IPv6 and multicast routes consume
144 bits per entry. If you use all IPv4/MPLS, you get 1048576 entries.
If you use all IPv6/multicast routes, you get 524288 entries. Your
actual usage will probably be somewhere in between. ACLs and Netflow are
different TCAM resources.

Also, you have to pre-"partition" the TCAM capacity and reboot in order
for the changes to take effect, so you'll need to decide your profile 
beforehand. The command to do that is "mls cef maximum-routes". You can 
also check your current utilization of forwarding tcam and acl/qos tcam 
with "show platform hardware capacity" on anything SXF or newer.

Richard A Steenbergen <ras at>
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)

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