want to understand Congestion avoidance using H QoS

[Corporate Noc]

Hi,

I am planning to deploy QoS on our network Infrastructure with following reservations.

Want to understand how much bandwidth will be considered for shaping in parent policy default class.
* it will be total interface bandwidth or it will be total bandwitdth availabe for default class.

Seek help in understanding HQoS operations.

=================================
policy-map Test
class VCON
    priority percent 30
class VOIP
    priority percent 10
class class-default
    shape average percent 100
   service-policy Test_CH
=================================
policy-map Test_CH
class DATA
    bandwidth percent 45
class class-default
    fair-queue
     random-detect dscp-based
================================
Class Map match-any VCON (id 15)

   Match   dscp af11 (10)
   Match ip  dscp af11 (10)

Class Map match-any VOIP (id 16)
   Match   dscp af31 (26)
   Match ip  dscp af31 (26)
   Match   dscp ef (46)
   Match ip  dscp ef (46)
   Match access-group name VOIP

Class Map match-any Ultimatix (id 3)
   Match ip  dscp af21 (18)
   Match   dscp af21 (18)
   Match access-group name DATA
===============================

Regards,
PJ

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Normally, you set the shaper's bandwidth to bandwidth that's available downstream and it applies to all traffic, not just default class traffic.  If the downstream bandwidth is the same, or more, than your egress interfaces bandwidth, you don't need a shaper since the interface itself provides the congestion point.  When your physical egress has more bandwidth than what's available downstream, the shaper creates a congestion point for that bandwidth that you can manage how the bandwidth is used.

For example, T1 to T3, no shaper needed.

T3 to T1, shape the T3 for the T1's bandwidth.  Often the latter is a cloud HQ connection with multiple branches.  For those, you shape for each branch's T1.