[ee122] definition of MTU (Re: hmwk problem Number 2.16)

Vern Paxson vern at icir.org
Fri Sep 21 10:23:49 PDT 2007

To bring some closure to this thread, MTU is alas yet another networking
term that's used a bit differently in different contexts.  If you ask a
practitioner "what's the Ethernet MTU" they may answer "1500 bytes", since
that's the largest payload an Ethernet frame can carry, or "1514 bytes",
since that's the size of the frame including the Ethernet header.  (They
might even answer "1536 bytes", which is the size in terms of timing of a
maximally large frame, as we'll see in a few lectures.)

It is usually clear from context which definition is being used.  For
problem P16, since we're not told anything about the link layer technology
or framing, it's reasonable to assume that MTU refers to the "largest
payload a frame can carry, not including headers" definition.


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