From: Chris Lewis \(chrlewis\) (chrlewis@cisco.com)
Date: Sat Jul 16 2005 - 09:38:52 GMT-3
He is setting the CIR to port speed. That is the easy part :)
Is this correct? Well, I guess it depends.
He has a central site connected via T1 to a frame cloud. By setting CIR
to T1 speed and mincir to 32k (and enabling adaptive shaping), the
central site port will transmit at a speed between 32k and 1.5M
depending on the presence of BECNs from the network. The remote ends
only have 64K lines, so sustained transfers from the central site to a
remote site will have to throttle down to this eventually. From that
perspective it is a bit pointless setting the CIR value so high on the
central site. Setting it to the remote port speed would mean fewer
dropped packets and no BECNs, a better choice if you have layer 3 QoS
mechanisms and want layer 3 to make drop decisions rather than the less
application aware layer 2.
However if at some point in the future there is a larger site added to
the network with a T1 access, you might want to have the CIR set to T1
on the central site so it can take advantage of the one site that can
accept T1 traffic rate, and accept packets to the slower sites
potentially being dropped and BECNs slowing down the transfer to those
sites.
Chris
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Shanky
Sent: Saturday, July 16, 2005 1:53 AM
To: ccielab@groupstudy.com
Subject: Frame Relay Traffic Shaping .. Karl Soli Example 5-17
Hi,
In the example, he is setting up the CIR to be the Phy Port speed ? Is
it correct ?
Regards
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