Cisco QoS Configuration

Optimize VOIP traffic with RTP compression and priority

contactus@wirethink.com (CiscoNET) — Wed, 31 Mar 2010 19:33:30 +0000

Here is simple configuration for VOIP traffic makes more efficiently handling by WAN or Interconnect.

Router-RTP-1(config)# class-map VOIP
Router-RTP-1(config-cmap)# match protocol rtp

Router-RTP-1(config)# policy-map VOIP_SHAPE
Router-RTP-1(config-pmap)# class VOIP
Router-RTP-1(config-pmap-c)# priority percent 75
Router-RTP-1(config-pmap-c)# compression header ip rtp

Applying LFI on Multilink PPP for Real-Time Traffic(VOIP)

contactus@wirethink.com (CiscoNET) — Wed, 31 Mar 2010 18:46:58 +0000

LFI stands for Link Fragmentation and interleaving is not of QoS mechanism. However, it is help for real-time traffic such as VOIP on small size of link. LFI on Multilink PPP allows large packets to be fragmented into a small size to fit a minimum delay requirement for real-time traffic. Also, interleaving function provides a special transmit queue for the high priority traffic can be sent earlier than others.

1. Configuring LFI on Multilink PPP

Router-LFI-1#conf t
Router-LFI-1(config)# interface multilink 1
Router-LFI-1(config-if)# ppp multilink fragment delay 10 ; 10ms for VOIP delay requirement
Router-LFI-1(config-if)# ppp multilink interleave
Router-LFI-1(config-if)# ip address 1.1.1.1 255.255.255.0
Router-LFI-1(config-if)# bandwidth 1536 ; Specify for auto fragmentation calculation
Router-LFI-1(config-if)# ppp multilink endpoint hostname

Router-LFI-1(config-if)# interface serial1/0
Router-LFI-1(config-if)# encapsulation ppp
Router-LFI-1(config-if)# ppp multilink group 1

VOIP QoS sample

contactus@wirethink.com (CiscoNET) — Mon, 29 Mar 2010 04:17:56 +0000

1. Configure class map

Cisco-QoS#conf t
Cisco-QoS(config)#class-map EF
Cisco-QoS(config-cmap)#match ip precedence 5

Cisco-QoS#sh class-map EF
Class Map match-any EF (id 1)
Match ip precedence 5

Cisco-QoS#sh class-map class-default
Class Map match-any class-default (id 0)
Match any

2. Configure policy map

Cisco-QoS#conf t
Cisco-QoS(config)#policy-map voip
Cisco-QoS(config-pmap)#priority percent 90
Cisco-QoS(config-pmap)#police cir percent 90 bc 25 ms be 25 ms
Cisco-QoS(config-pmap-c-police)#conform-action transmit
Cisco-QoS(config-pmap-c-police)#exceed-action drop

Cisco-QoS(config-pmap-c-police)#class class-default
Cisco-QoS(config-pmap-c)#random-detect
Cisco-QoS(config-pmap-c)#random-detect precedence 0 19 64 1
Cisco-QoS(config-pmap-c)#random-detect precedence 1 19 64 1
Cisco-QoS(config-pmap-c)#random-detect precedence 2 19 64 1
Cisco-QoS(config-pmap-c)#random-detect precedence 3 19 64 1
Cisco-QoS(config-pmap-c)#random-detect precedence 4 19 64 1
Cisco-QoS(config-pmap-c)#random-detect precedence 5 19 64 1
Cisco-QoS(config-pmap-c)#random-detect precedence 6 64 70 1
Cisco-QoS(config-pmap-c)#random-detect precedence 7 64 70 1

Cisco-QoS#sh policy-map voip
Policy Map voip
    Class EF
     police cir percent 90 bc 25 ms be 25 ms
       conform-action transmit
       exceed-action drop
      Strict Priority
      Bandwidth 90 (%)
    Class class-default
      Bandwidth 10 (%)
            exponential weight 9
            class    min-threshold    max-threshold    mark-probablity
            ----------------------------------------------------------

            0          19                 64               1/1
            1          19                 64               1/1
            2          19                 64               1/1
            3          19                 64               1/1
            4          19                 64               1/1
            5          19                 64               1/1
            6          64                 70               1/1
            7          64                 70               1/1
            rsvp       -                  -                1/10

3. Apply service policy to interface

Cisco-QoS#conf t
Cisco-QoS(config)#interface serial1/1
Cisco-QoS(config-if)#service-policy output voip