[e2e] MTU of a loopback interface?

[Jeffrey A. Six]

e2e,

Me and a colleague have been having a discussion about why loopback
interfaces have an MTU.  Is this done for any particular reason?  If the
data being send/received is never actually put on the wire (or other
physical layer), why does the link layer provide a link layer MTU?  I fail
to see a reason for this.  Also, if there is such a MTU, how is the value
determined?  Is this just an implementation issue for those implementing the
loopback interface code?  What design criteria would go into this
determination?

Thanks,
-j6

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Jeffrey A. Six
University of Delaware                jeffsix at udel.edu
Computer & Information Sciences       http://www.eecis.udel.edu/~six
Electrical & Computer Engineering

"I build circuits everyday.  I don't know how they work, but. . ."