Route Summarization

[eoronsaye]

Can someone please help with this, I have been scratching my head over this for the past few days. I have setup an OSPF environment with area 0 as the backbone, area 1 and 2. I have an additional RIP environment. The loopback addresses in area 1 has been summarised in R2 which is the ABR (Area Border Router). This has also been redistribute from OSPF to RIP. The issue I am having is R6 can see summarised loopback addresses of R1 in its routing table but when I enter the command show ip route summary in R6 to check memory size this seems to have increased rather than decrease. Before summarizing memory size was 3960, after summarizing memory size has now increased to 4596 please see attached files labelled

Can anyone kindly explain the reason for this as my understanding was once you have a summarized route this should consume less memory, reduce CPU utilization, better convergence etc

Look forward to hearing from you

Regards

Ese 

[e.ciollaro]

Hi eoronsaye

it's intersting, could you upload GNS file, so I can try to run your lab and make some troubleshooting ?

enrico

[eoronsaye]

Hi Enrico

Thanks for getting back, please see gns3 file

Look forward to hearing from you

Ese

[e.ciollaro]

Hi,

it's quite strange. My first clue was that memory usage was due to RIP holdown time but memory is higher then supposed to be also after RIP flushed all routes. So my second idea was to save config with summarization enable, switching off router in GNS and then restarting them and.. SURPRISE: after reload the memory usage is reduced (see attached file).

I guess that the behaviour is due to the way IOS uses  memory. It's seems that some memory structure is not delete when routes are replaced by the summary   or something like that. 

Try and let me know if you have the some result (I had some problem importing in GNS so I have to manually complete some config)

Bye,

enrico