From: Ian Blaney (ian.blaney@gmail.com)
Date: Sat Feb 17 2007 - 09:45:13 ART
Hi GS
Trying once again as I never got any real answer on my last try asking
this question.
Is this a mistake on CCO or in my head?
http://www.cisco.com/univercd/cc/td/doc/product/software/ios124/124cr/hqos_r/qos_s1h.htm#wp1085303
They give an example of using shape peak
The following example uses peak rate shaping to ensure a bandwidth of
300 kbps but allow throughput up to 512 kbps if enough bandwidth is
available on the interface:
bandwidth 300
shape peak 512000
If I apply this to an interface and look at the output of show
policy-map int. The Target rate is 1024000 double the CIR ie peak rate
= CIR(1 + Be / Bc)
policy-map SHAPE
class PREC
bandwidth 300
shape peak 512000
Service-policy output: SHAPE
Class-map: PREC (match-all)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: precedence 5
Queueing
Output Queue: Conversation 265
Bandwidth 300 (kbps)Max Threshold 64 (packets)
(pkts matched/bytes matched) 0/0
(depth/total drops/no-buffer drops) 0/0/0
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
1024000/512000 3200 12800 12800 25 3200
Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 0 0 0 0 0 no
Assuming a minimum guaranteed bandwidth of 300K should it not be
somthing like below
The target rate is now 512000 and CIR is minimum guaranteed bandwidth.
policy-map SHAPE
class PREC
bandwidth 300
shape peak 300000 9000 6360
Bc = 300000 * (30/1000) = 9000
Be = (512000 - 300000) * (30/1000) = 6360
R2#sh policy-map int
Serial1/0
Service-policy output: SHAPE
Class-map: PREC (match-all)
0 packets, 0 bytes
5 minute offered rate 0 bps, drop rate 0 bps
Match: precedence 5
Queueing
Output Queue: Conversation 265
Bandwidth 300 (kbps)Max Threshold 64 (packets)
(pkts matched/bytes matched) 0/0
(depth/total drops/no-buffer drops) 0/0/0
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
512000/300000 1920 9000 6360 30 1920
Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 0 0 0 0 0 no
Your help is very much appreciated
Ian
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