I'm sure that somebody else will give a much more complete answer, but in a
nutshell...
Don't forget that there is more than one component to 'routing'. The
'routing process' (I'm using Cisco terms out of my rather old CIT notes
here, which in my opinion are thoroughly confusing in this context)
identifies the best path to a destination. This is what OSPF, EIGRP, etc
etc do. The routing process builds the routing table.
The switching process (we're still talking about routers here) moves
traffic from an input interface to an output interface. It uses the
routing table to work out which interface is the output interface.
It is the switching process (i.e. moving packets, based on information in
the routing table) that is offloaded to the SP. The RP still does the
routing process (i.e. working out where to move the packets - building the
routing table).
JMcL
---------------------- Forwarded by Jenny Mcleod/NSO/CSDA on 23/01/2001
09:17 pm ---------------------------
[EMAIL PROTECTED]@groupstudy.com on 23/01/2001 03:05:02 pm
Please respond to [EMAIL PROTECTED]
Sent by: [EMAIL PROTECTED]
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cc:
Subject: But isn't that the routers job???
Hey Group,
Me again. I'm reading for my CIT and am at the section where it goes
into detail of the various switching methods in the router (i.e., silicon,
CEF, autonomous, etc.) I understand how all this works and understand how
the
SP takes a lot of the stress away from the RP and this is good because your
avoiding bogging the RP/CPU down. I have a problem with these statements
though and want some clarification...
Taken form the book (Lammle's CIT p. 173):
"This is just another reason why switching is such a good practice.
Why
burden the RP with every packet if it's not necessary? By using switching
methods, the RP is free to use valuable CPU time on more important things
than doing route lookups for every packet that comes in the router."
Correct me if I'm wrong but isn't that what a routers supposed to do???
What
else does the RP have to do that is more important than ROUTING? I may be
overanalyzing this but it just seems that he's saying that the RP has
better
things to do like make coffee, rather than route.
Basically, could somebody give me a list of some other things the RP/CPU
has
to do other than route lookups...(I know there are access-lists and other
CPU
things here, I just would like a solid list to remember). Thanks team,
Mark Zabludovsky ~ CCNA, CCDA, 3/4-NP
<A HREF="mailto: [EMAIL PROTECTED]">[EMAIL PROTECTED]</A>
"Even if I knew I had only 1 more week to live, I would still schedule
my CCIE lab. I would just have to work a little harder I guess. After all,
without any goals in life, I'm dead already."
~Mark Zabludovsky~
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