Hey all,

I am just wondering, what is the benifit of ICMP ping in Ethernet network with more then 1500 bytes (which is the maximum MTU in a standard gear).
Is this for checking how the NIC/Gear/OS can handle defragmented datagrams ?

Much thanks.

Howdy,

ICMP is used to send error messages regarding datagrams.
The ping feature only checks IP connections.

Woodmann

zdr,
i think woodmann missed the point of your question, the 1500 MTU limit as you have figured out already is for a single formatted packet before it is fragmented to create the next packet.... some issues can be diagnosed by sending packets of different sizes, some setups, like the cisco VPN client and DSL lines have to be set to MTU 1300 or it becomes painfully slow, if not completely un-functional. another time we found a bug in a F5 network load balancer by sending it huge "ping" requests thru an ipsec tunnel and watching the packet re-sequencing on the other side. it is simply another tool in the toolbax that helps you find the solution to the proverbual "crackme"... it can also be used for denial of service attacks (DOS) as it takes more resources (cpu, memory) of the systems that have to put these packets back together again.

there maybe more to it... but i hope this helps some.

korvak