Port speed is the speed of the physical connection going into your site. So
for example, you may purchase at T1 connection from your location to AT&T's
frame relay network. So your port speed is that of a T1.
A PVC is Permanent Virtual Circuit and used to connect your site, via the
frame relay network, to some distant location. Think of it as a pathway
through the frame network. Each PVC is identified via a DLCI.
The CIR is Committed Information Rate and is the rate the frame-relay
service is guaranteeing you will receive through the PVC. Usually the CIR
is less or equal to the port speed. But it is common to see the aggregate
of all of the CIR's to be slightly bigger then the port speed.
Also the CIR is the guaranteed bandwidth. Sometimes, if the bandwidth is
available, they will allow you to send beyond your CIR. Some providers will
set the Discard Eligible (DE)bit for traffic that is above the CIR. The DE
bit tells the network this is "free" traffic and may be discard at any time
the network become congested.
Good luck,
Paul Borghese
----- Original Message -----
From: "Thomas"
To:
Sent: Thursday, June 14, 2001 3:02 AM
Subject: CIR/Port speed/PVC speed [7:8480]
> Hi All,
>
> Can someone definde the difference between CIR, Port speed and PVC speed
on
> routers? I am so confused on these items with my current ISPs. Thanks in
> advance!!!
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=8505&t=8480
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