[f-nsp] CAM and ip net-aggregate or ip supernet aggregate - does it help to free the cam up ? WAS:AW: cam strangeness

[Gerald Krause]

On Monday 06 March 2006 16:48, Gunther Stammwitz wrote:
> What do the others say: does aggregation help and does the cam
> usually fill up in an isp enviorment?

   I do not use aggregation yet but this might be also interesting: I 
see a lot of /32 CAM entries for destinations that are reachable 
through a supernet which the router learned via OSPF from two neighbors 
via two Ethernet links (= 4 equal paths):


(System: NI4GMR/B2P08000)

#sh ip route 212.79.18.100
Total number of IP routes: 180834
        Destination     NetMask         Gateway         Port Cost Type
        212.79.0.0      255.255.192.0   212.79.49.135   1/4  20   O
        212.79.0.0      255.255.192.0  *212.79.49.131   1/4  20   O
        212.79.0.0      255.255.192.0   212.79.48.3     1/3  20   O
        212.79.0.0      255.255.192.0   212.79.48.5     1/3  20   O
#sh cam ip 1/1 | inc 212.79.0.0
(nothing)

   but:

#sh cam ip 1/1 | inc 212.79.18
  1   8374    212.79.18.198/32  00e0.1e7e.4101    37       1   ether 1/4
  1   8642     212.79.18.53/32  0050.0b3b.5400   120       1   ether 1/4
  1   9142     212.79.18.94/32  00e0.1e7e.4101    30       1   ether 1/4
  1  10131     212.79.18.44/32  0050.0b3b.5470    52       1   ether 1/3
  1  10601     212.79.18.68/32  00e0.1e7e.4101     7       1   ether 1/4
  1  11572    212.79.18.100/32  00e0.1e7e.4102   125       1   ether 1/3


   First I thought this could be caused by the load balancing but then I 
found an other network (reachable via 2 equal paths) that have a /24 
CAM entry:


#sh ip route 212.79.56.156
Total number of IP routes: 180855
        Destination     NetMask         Gateway         Port Cost Type
        212.79.56.0     255.255.255.0   212.79.48.4     1/3  20   O
        212.79.56.0     255.255.255.0  *212.79.49.129   1/4  20   O
Gateway: 212.79.49.129
CAM Entry Flag: 0000000300000000H

#sh cam ip 1/1 | inc 212.79.56
  1  10933      212.79.56.0/24  0001.6482.5c00     0       1   ether 1/4


   Reading the 'Changing CAM Partitions' document on the Foundry website 
does not really enlighten me - especially "Example 2" looks weird for 
me. In my opinion the /32's would make sense for directly connected 
systems or host routes only.... or have I missed something?


--
Gerald