4507 Catalyst Problem

Unanswered Question
Jul 31st, 2008

I have two Catalyst 4507 as core switch. They are uplink with each other on redundent fiber cable. I am also running HSRP for each vlan configured on it. Everything was working fine. But this morning suddendly communication stop. No response of telnet. When I console the switch i found following errors on cosole

%% Low on memory; try again later

%% Low on memory; try again later

%% Low on memory; try again later

%% Low on memory; try again later

%% Low on memory; try again later

%% Low on memory; try again later

%% Low on memory; try again later

%% Low on memory; try again later

%% Low on memory; try again later

%% Low on memory; try again later

on the 2nd core switch i found this error on console

15w4d: %C4K_EBM-4-HOSTFLAPPING: Host 00:0E:0C:EB:37:2F in vlan 2 is flapping between port Gi3/1 and port Gi3/2

15w4d: %C4K_EBM-4-HOSTFLAPPING: Host 00:1D:45:61:A4:2B in vlan 3 is flapping between port Gi3/1 and port Gi3/2

15w4d: %C4K_EBM-4-HOSTFLAPPING: Host 00:0E:0C:C0:4B:50 in vlan 2 is flapping between port Gi3/2 and port Gi3/1

15w4d: %C4K_EBM-4-HOSTFLAPPING: Host 00:1D:45:61:A3:C5 in vlan 3 is flapping between port Gi3/2 and port Gi3/1

15w4d: %HSRP-4-DUPADDR: Duplicate address 172.28.63.66 on Vlan2, sourced by 0000.0c07.ac0a

Then i remove the rundent fiber uplink and switches start responding. Even after placing the redundent fiber uplink back starts working.

why i got memeory error on core switch 1 and why this happened. I didnt change anything for the last two months.

I have this problem too.
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hasnain321 Thu, 07/31/2008 - 04:29

Hi

I got same message 2 months back. What I was able to figure out some process was eating up a lot of memory.

A system was having too many web session that was the cause for this. I plugged that out from network and everything worked fine.

According to documentation of cisco

Memory Fragmentation Problem or Bug

This situation means that a process has consumed a large amount of processor memory and then released most or all of it, leaving fragments of memory still allocated either by this process, or by other processes that allocated memory during the problem. If the same event occurs several times, the memory may fragment into very small blocks, to the point where all processes requiring a larger block of memory cannot get the amount of memory that they need. This may affect router operation to the extent that you cannot connect to the router and get a prompt if the memory is badly fragmented.

This problem is characterized by a low value in the "Largest" column (under 20,000 bytes) of the show memory command, but a sufficient value in the "Freed" column (1MB or more), or some other wide disparity between the two columns. This may happen when the router gets very low on memory, since there is no defragmentation routine in the IOS.

If you suspect memory fragmentation, shut down some interfaces. This may free the fragmented blocks. If this works, the memory is behaving normally, and all you have to do is add more memory. If shutting down interfaces doesn't help, it may be a bug. The best course of action is to contact your Cisco support representative with the information you have collected.

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