From: Howard C. Berkowitz (hcb@xxxxxxxxxxxx)
Date: Fri Mar 29 2002 - 11:17:55 GMT-3
>I believe that non blocking states that a switch fabric can support all
>ports at maximum speed and throughput without running out of capacity, where
>as a blocking fabric cannot. There is a good book that explains cross bar
>and shared bus architectures in routers, I assume that the same would follow
>for switches. The title is Inside Cisco IOS Software Architecture from
>Cisco Press, it is also very good at the explanation of the difference
>between switching methods within routers, some of the stuff that it is not
>easy to find information on.
Your definition of nonblocking is correct. There is also an
assumption that all traffic is of equal priority, and every input
port will go to an unique output port of the same speed -- no
contention for the output port. You may want to look at the
measurement methods in RFC 2544.
Excellent book, which I recommend. I did spend quite a bit of time
on these issues in my book, "Designing Routing Architectures for
Enterprise Networks."
Shared bus reaches its architectural limits certainly by 10 Gbps, and
possibly a good deal less than that. Crossbar, without much
question, is most scalable for unicast traffic. Shared memory, which
may be superior for multicast, is more complex to design as part of a
system. Its performance tends to be fine until its utilization hits
a certain level, and then it slows down radically.
>
>-----Original Message-----
>From: Neil G. Legada [mailto:nglegada@hotmail.com]
>Sent: Friday, March 29, 2002 7:38 AM
>To: ccielab@groupstudy.com
>Subject: Catalyst Switching Architecture
>
>
>Hi Group,
>
>Anybody got a good explanation (or links) about the differences and
>advantages between crossbar, shared bus (central/distributed) and shared
>memory swithing architectures ??? Also those terms as blocking and
>non-blocking, there significance on switching performance.
>
>Appreciate any response.
>
>
>Thanks and regards,
>Neil
-- "What Problem are you trying to solve?" ***send Cisco questions to the list, so all can benefit -- not directly to me*** ******************************************************************************* * Howard C. Berkowitz hcb@gettcomm.com Chief Technology Officer, GettLab/Gett Communications http://www.gettlabs.com Technical Director, CertificationZone.com http://www.certificationzone.com "retired" Certified Cisco Systems Instructor (CID) #93005
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:57:25 GMT-3