At 09:28 17/03/2001 -0800, Joe Touch wrote:
Other than refining that rule, are there any other observable differences
between routers and switches?
trying to expand on my koan-sized definition.....
In an ideal world, routers would obey all the restrictions and caveats of
RFC 1812 and RFC 2644.
In the real world, not only is every single rule of the RFCs bent, broken
or render irrelevant by some device or another, but the breaking is usually
sold as a feature by some company's sales force.
That's my reason to use the TTL decrement; if someone shows me a device
where a packet comes in on one interface with a certain TTL, and it comes
out on another interface with a lower TTL but no other significant changes,
I call it a router.
If it is incapable of not doing other significant damage, I call it an
application layer gateway, a NAT box, or something else, but not a router.
If it doesn't decrement the TTL, and doesn't do anything else either to the
IP portion, I call it a layer 2 switch (or a bridge, if I am feeling
But that is my definition. Your mileage may vary.
Harald Tveit Alvestrand, alvestrand(_at_)cisco(_dot_)com
+47 41 44 29 94
Personal email: Harald(_at_)Alvestrand(_dot_)no