cisco catalyst 3750-x icmp delay to default gateway

[mohamed fayz]

hai,

i am facing a problem when the client vlan is commmunicating with the default gateway on the core 3750-x.

ios in 3750-x core is  3750e-universalk9-mz.150-2.SE.bin.  But, client to client communication is happening without any dealy and icmp is less than 1 ms always.

When try to ping default gateway of client vlan, it is getting delayed (variable icmp delays). Is this an ios bug???? please suggest. thisis the latest ios which cisco release! please suggest.

[Jon Marshall · Accepted solution]

It might not necessarily be a bug.

When you ping from a client to another client the switch simply hardware switches this packet from one port to another. The switch has no idea the packet is an ICMP packet and doesn't care.

When you ping the switch itself this packet must be processed in software and be handled by the main CPU. The switch also uses the main CPU for managing control protocols such as STP/CDP. The key thing is to understand that the packet is not handled in hardware and so this may account for why you are seeing delays. It all depends on what else the switch is doing in terms of software.

So it's more a question of -

1) what sort of delays are you seeing - huge delays or just longer delays relative to client to client communication

2) how important is it to have low response times when pinging the switch. Remember the response times of pinging to the switch are not necessarily related to how the switch is forwarding packets from clients to other clients and servers.

Jon

[mohamed fayz]

Thank You Jon.

Client to client communication, there is no issue. its working smoothly without any delyas. but when a client is trying to communicate with default gateways, it is getting delayed, i mean icmp to the switch software only.!!!

Everything is working fine except this.