RE: QoS Shaping Hierarchical Policy Maps issue !!!

From: Daniel Kutchin (daniel@kutchin.com)
Date: Sat Nov 01 2008 - 17:49:27 ARST


I verified the Book to be correct:

Each class in the child policy-map references the TOTAL bandwidth available.

The parent policy-map determines the TOTAL available bandwith, which is 384k

Issue the command
"sho policy-map int" to see how the bandwidth is shared out

Router(config-if)#do sh policy-map int s0/0 ou

 Serial0/0

  Service-policy output: parent

    Class-map: class-default (match-any)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any
      Traffic Shaping
           Target/Average Byte Sustain Excess Interval Increment
             Rate Limit bits/int bits/int (ms) (bytes)
           384000/384000 2400 9600 9600 25 1200

        Adapt Queue Packets Bytes Packets Bytes Shaping
        Active Depth Delayed Delayed Active
        - 0 0 0 0 0 no

      Service-policy : child

        Class-map: x (match-all) <---
          0 packets, 0 bytes
          5 minute offered rate 0 bps, drop rate 0 bps
          Match: ip precedence 5
          Queueing
            Output Queue: Conversation 41
            Bandwidth 50 (%) <---
            Bandwidth 192 (kbps) Max Threshold 64 (packets)<---192k
            (pkts matched/bytes matched) 0/0
        (depth/total drops/no-buffer drops) 0/0/0

        Class-map: y (match-any)
          0 packets, 0 bytes
          5 minute offered rate 0 bps, drop rate 0 bps
          Match: ip precedence 2
            0 packets, 0 bytes
            5 minute rate 0 bps
          Match: ip precedence 3
            0 packets, 0 bytes
            5 minute rate 0 bps
          Match: ip precedence 4
            0 packets, 0 bytes
            5 minute rate 0 bps
          Queueing
            Output Queue: Conversation 42
            Bandwidth 20 (%) <---
            Bandwidth 76 (kbps) Max Threshold 64 (packets)<---76k
            (pkts matched/bytes matched) 0/0
        (depth/total drops/no-buffer drops) 0/0/0

        Class-map: z (match-any)
          0 packets, 0 bytes
          5 minute offered rate 0 bps, drop rate 0 bps
          Match: ip precedence 0
            0 packets, 0 bytes
            5 minute rate 0 bps
          Match: ip precedence 1
            0 packets, 0 bytes
            5 minute rate 0 bps
          Queueing
            Output Queue: Conversation 43
            Bandwidth 10 (%) <---
            Bandwidth 38 (kbps) Max Threshold 64 (packets)<--38k
            (pkts matched/bytes matched) 0/0
        (depth/total drops/no-buffer drops) 0/0/0

        Class-map: class-default (match-any)
          0 packets, 0 bytes
          5 minute offered rate 0 bps, drop rate 0 bps
          Match: any
Router(config-if)#

Daniel

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Wittawat H.
Sent: Samstag, 1. November 2008 18:03
To: ccielab
Subject: QoS Shaping Hierarchical Policy Maps issue !!!

Dear All,

Please help me to clarify this configuration that stated below.

policy-map child
 class x
  bandwidth percent 50
 class y
  bandwidth percent 20
 class z
  bandwidth percent 10

policy-map parent
 class class-default
  shape average 384000
  service-policy child

int s0/0
 service out parent

In my opinion, I think that traffic that going out of interface serial 0/0
is rate-limited to 384 kbps total. and then

class x should get minimum bandwidth guaranteed to 384 kbps x 0.5,
class y should get minimum bandwidth guaranteed to (384 kbps x 0.5) x 0.2
class z should get minimum bandwidth guaranteed to ((384 kbps x 0.5) x 0.2)
x 0.1

because I used "bandwidth percent" command, not "bandwidth remaining
percent" one.

But, according to "Implementing Cisco Quality of Service" volume 2, version
2.2 study guide, it stated that

class x get minimum bandwidth guaranteed to 384 kbps x 0.5 = 192 kbps
class y get minimum bandwidth guaranteed to 384 kbps x 0.2 = 76.8 kbps
class z get minimum bandwidth guaranteed to 384 kbps x 0.1 = 38.4 kbps

So, these result made me confusing about "bandwidth percent" command
accompany with shaping hierarchical policy map.

Thank you in advance.

Best Regards,
Wittawat H.

Blogs and organic groups at http://www.ccie.net



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