RE: [nsp] enquiry on extended ping packet size

From: David Sinn (dsinn@microsoft.com)
Date: Thu Apr 12 2001 - 12:46:12 EDT


What is your MTU on the interfaces in question? If they don't match
(for what ever reason) the pings will fail.

What version of IOS are you running? Some versions have bugs or are
missing fragment ability depending on switching mode.

Are you shaping your ATM VC? Depending on MTU of the ATM interface, and
if you have shaping turned on, you could be overwhelming the output
queue for the ATM VC, and thus are dropping some subset of the ICMP
packets so that when either end tries to reassemble the packet it is
missing data and doesn't pass CRC.

These are but a few issues that you can run into, there are others.

David

-----Original Message-----
From: eric chan [mailto:bigeric123@hotmail.com]
Sent: Thursday, April 12, 2001 12:05 AM
To: cisco-nsp@puck.nether.net
Subject: [nsp] enquiry on extended ping packet size

i would like to perform back to back extended ping with different packet

size, but i found that for fastethernet , i can ping with packet size
>?5000, but with ATM or gigabit, i can't even ping
with packet size 5000 byptes. is there any constrain on icmp packet
size
on atm and gigabit ?

thanks

eric
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