QOS - Polycom traffic over 2MB Serial

Answered Question
Nov 24th, 2009
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Polycom teleconference traffic requires 1.2 MB (bandwidth). Site A has 2 x 2MB serial circuits to Site B.


What is best pratice to apply QOS on both serial interfaces (ingress/egress) on both sites.



Please advise.



### Site A  Router ###


access-list 104 permit tcp any any range 3230 3243
access-list 104 permit udp any any range 3230 3285


class-map match-all POLYCOM-CONF
match access-group 104


policy-map POLY-POLICY
class POLYCOM-CONF


class class-default
fair-queue


interface Serial3/0:0
description "Link to Site B"
bandwidth 2048
ip address 10.218.92.25 255.255.255.252
ip load-sharing per-packet
service-policy output POLY-POLICY
service-policy input POLY-POLICY


interface Serial3/1:0
description "Link to Site B"
bandwidth 2048
ip address 10.218.92.21 255.255.255.252
ip load-sharing per-packet
service-policy output POLY-POLICY
service-policy input POLY-POLICY



### Site B Router ###


access-list 104 permit tcp any any range 3230 3243
access-list 104 permit udp any any range 3230 3285


class-map match-all POLYCOM-CONF
match access-group 104


policy-map POLY-POLICY
class POLYCOM-CONF
priority xxxx

class class-default
fair-queue


interface Serial3/0:0
description "Link to Site A"
bandwidth 2048
ip address 10.218.92.25 255.255.255.252
ip load-sharing per-packet
service-policy output POLY-POLICY
service-policy input POLY-POLICY


interface Serial3/1:0
description "Link to Site A"
bandwidth 2048
ip address 10.218.92.21 255.255.255.252
ip load-sharing per-packet
service-policy output POLY-POLICY
service-policy input POLY-POLICY

Correct Answer by Giuseppe Larosa about 7 years 5 months ago

Hello Colm,


>> If I apply 1200kbps (PQ) for teleconference traffic on both serial interfaces, does this allow all traffic 'default' to use the full 2mb on both serial interfaces when teleconference is not being used?


yes, this is the elasticity of LLQ CBWFQ




Hope to help

Giuseppe

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Giuseppe Larosa Tue, 11/24/2009 - 07:34
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Hello Colm,


nice to hear from your you


you are using load sharing per packet so each flow will see its packets sent in round robin over the two serial links.


you need also to provide enough resources in case one link has failed.



I would use a class-map with bandwidth 1200 kbps on both links


class-map polycom

! your match condition here a simple ACL should be enough

match access-group 111


I see you want to use priority command that is possible too in that case I would use priority 1200


in normal conditions only 600 kbps will be used on each link.


Unused resources are available to other traffic classes so this is not a problem to have priority 1200 on interface


Be also aware that if the two links have different delays and / or are going though different WAN provider(s) switches there is potential for out of order that can be a problem.


incoming policy doesn't play a key role here


Hope to help

Giuseppe

colmgrier Tue, 11/24/2009 - 07:52
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Hi Giuseppe,


Thanks for the below info.


If I apply 1200kbps (PQ) for teleconference traffic on both serial interfaces, does this allow all traffic 'default' to use the full 2mb on both serial interfaces when teleconference is not being used?


Giuseppe wrote...

Unused resources are available to other traffic classes so this is not a problem to have priority 1200 on interface


### Config to be applied to both Routers ####


access-list 104 permit tcp any any range 3230 3243
access-list 104 permit udp any any range 3230 3285


class-map match-all POLYCOM-CONF
match access-group 104


policy-map POLY-POLICY
class POLYCOM-CONF
priority 1200
class class-default
fair-queue

interface Serial3/0:0
bandwidth 2048
ip address 10.218.92.25 255.255.255.252
ip load-sharing per-packet
service-policy output POLY-POLICY


interface Serial3/1:0
bandwidth 2048
ip address 10.218.92.21 255.255.255.252
ip load-sharing per-packet
service-policy output POLY-POLICY



Regards,

Colm

Correct Answer
Giuseppe Larosa Tue, 11/24/2009 - 08:00
User Badges:
  • Super Silver, 17500 points or more
  • Hall of Fame,

    Founding Member

Hello Colm,


>> If I apply 1200kbps (PQ) for teleconference traffic on both serial interfaces, does this allow all traffic 'default' to use the full 2mb on both serial interfaces when teleconference is not being used?


yes, this is the elasticity of LLQ CBWFQ




Hope to help

Giuseppe

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