From: Dennis J. Hartmann (dhartma5@optonline.net)
Date: Fri May 06 2005 - 16:58:53 GMT-3
I don't "believe" we have to go to that level (figuring out the Tc),
but I could be wrong. One of the reasons why Cisco is going to smaller Tc
intervals is because they're pushing to have all of their mechanisms
optimized for voice over IP. Since the 7900 phones have a default 20ms
sampling interval, 25ms is close.
You're absolutely right about the Bc and the Be reccomendations,
although I have seen different numbers in "some" configuration examples
where the traffic is voice only.
-Dennis Hartmann
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
sumit.kumar@comcast.net
Sent: Friday, May 06, 2005 3:48 PM
To: ccielab@groupstudy.com
Subject: Shaping vs. Police values
Groupies,
CCIE Prac studies vol-2 : Cisco recommends the Bc vlaue should be equal to
CIR*1.5 seconds. and Be= Bc*2.
The earlier recommendation for FRTS are Tc= (125ms) To test the router
defaults I specified a CIR of 2 Mbps w/o Bc and Be with CB-Policing,
CB-shaping and GTS on interface. Here's what it shows:
For CB-shaping;
IER7#show policy-map interface
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
2000000/2000000 12500 50000 50000 25 6250
Adapt Queue Packets Bytes Packets Bytes Shaping
For CB-Policiing :
Serial0/0:0
Service-policy output: test
cir 2000000 bps, bc 62500 bytes
For GTS on interface:
#Show run int serial 0/1
interface Serial0/1
traffic-shape rate 2000000 50000 50000 1000
Looks like the default Tc for CB-shaping and GTS is set to 25ms but for
CB-policing is 250 ms Anyone can explain this, what value should we use in
Lab ?
thanks
Sumit
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