[e2e] end2end-interest Digest, s/Vol 53, Issue 10 / sacred cows, sacre bleu/

Noel Chiappa jnc at mercury.lcs.mit.edu
Fri Jul 11 15:54:19 PDT 2008

    > From: Joe Touch <touch at ISI.EDU>

    >> ICMP is layered on top of ip as is tcp - icmp talking to tcp is not a
    >> layer violation.

    > If you call ICMP a transport layer (fair enough)

This is a bit of a side point, but... 

I would not call ICMP a transport layer. It's part of the internetwork layer.

Where I think the confusion comes from is that the ICMP _protocol_ is carried
on top of the IP _protocol_. But protocol != layer.

(Standard rant about how any layer model is a poor match to reality in the
network, because the sub-system dependency graph is actually a tree, not
anything linear, elided...)


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