[c-nsp] Sup2s and counting routes

[David Sinn]

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The "show mls cef summ" tells you how many are being pushed to the  
TCAM and is what to worry about running out of space on the PFC2/3B's  
of the world.  If your code supports it, a "show mls cef max" is  
informative of how close you are (3BXL below):

#sho mls cef max
FIB TCAM maximum routes :
=======================
Current :-
- -------
IPv4 + MPLS         - 512k (default)
IPv6 + IP Multicast - 256k (default)

I believe the difference between the "show ip route sum" and the  
actual FIB is related to legacy classful distinctions in the IOS's  
view, along with it's fetish to infer "networks".  Which is why the  
output of a "show ip route" has the "subnetted" line:

      203.238.37.0/24 is variably subnetted, 3 subnets, 2 masks
B       203.238.37.0/24 [20/0] via 209.124.178.5, 7w0d
B       203.238.37.96/27 [20/0] via 209.124.178.5, 2w2d
B       203.238.37.128/27 [20/0] via 209.124.178.5, 2w2d

And thus it invents a "network" out of a CIDR block:

      211.248.61.0/25 is subnetted, 1 subnets
B       211.248.61.0 [20/0] via 209.124.178.5, 1w3d


David

On Sep 6, 2007, at 8:55 AM, Jon Lewis wrote:

> With the useful life of Sup2s as full-table BGP routers coming to  
> an end
> sometime real soon, I've been looking at our 6509s trying to figure  
> out
> just how much time we have, and I'm a bit confused.
>
> #sh ip ro sum | inc Net|Tot
> Route Source    Networks    Subnets     Overhead    Memory (bytes)
> Total           129159      103219      14760368    40044640
>
> Adding up the networks and subnets, I get 232378.
>
> #sh mls cef summary | inc routes
> Total routes:                230023
>      IP unicast routes:       230023
>      IPX routes:              0
>      IP multicast routes:     0
>
> According to CEF, I don't quite have 232378 routes.  Is one of these
> "totals" more correct than the other?  Why might they differ?
>
> ----------------------------------------------------------------------
>   Jon Lewis                   |  I route
>   Senior Network Engineer     |  therefore you are
>   Atlantic Net                |
> _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
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