From: Pavel Bykov (slidersv@gmail.com)
Date: Mon Nov 24 2008 - 19:43:00 ARST
Ali, here are the answers:
What is crossbar switching?
-- non-blocking communication matrix, originated in telephony systems (i.e.
the switching lady), were any input can communicate directly to any output.
It is also the difference between the 6000 and 6500
What is DCEF?
How does DCEF work?
--Distributed CEF distributed the forwarding logic to the fabric enabled
linecards with DCEF daughter card installed. A complete copy of TCAM is
copied using EOBC (ethernet out of band channel, 100 Mbps, Half duplex, thir
pipe on the shared bus) to the linecard directly, and provides for up to
48Mpps local switching capacity. PFC capacity is not used by the cards and
DCEF sends packets over MEDUSA to CROSSBAR prepended with internal logic
telling what should be done with packet (there is a possibility to sniff out
directly this COMPLETE packet right off the crossbar using service internal
and built in capture mechanisms)
What benefit does a fabric enabled module have?
-- See above. Increased switching throughput...
What are some reasons traffic would result in a CEF punt? Or a glean adj?
-- CEF punt is another way of saying packet has to be moved from the data
plane to control plane, i.e. the RP. Glean adjacency is waiting from an ARP
resolution
How could you prevent these issues? Would they affect performance?
-- lol. can't really prevent them completely, but you can work hard to
minimize them. Use only features that are supported in HW. Minimise the use
of features that are SW-only or HW assisted. Use COPP to protect the system
further... blah blah.
...and so on. Ali, come to your local Cisco training. Course code is CAT6KS.
:)
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-- Pavel Bykov ---------------- Don't forget to help stopping the braindumps, use of which reduces value of your certifications. Sign the petition at http://www.stopbraindumps.com/Blogs and organic groups at http://www.ccie.net
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