Why should you police VoIP to 128kpbs on an ingress port?

[wchatcher]

In all of the examples I have looked at in the QoS SRND and the Medianet Campus QoS Design 4.0 guide they show inbound VoIP being policed at 128kbps and inbound signaling being policed at 32kbps on the ingress switch port.  None of the examples really say why they are policing at this rate.  What are the risks/effects should you police inbound VoIP at say 256kbps?

C3750-E(config)#policy-map PER-PORT-POLICING

C3750-E(config-pmap)# class VVLAN-VOIP

C3750-E(config-pmap-c)#  set dscp ef

C3750-E(config-pmap-c)#  police 128k 8000 exceed-action drop

 ! VoIP is marked EF and policed to drop at 128 kbps

C3750-E(config-pmap-c)# class VVLAN-SIGNALING

C3750-E(config-pmap-c)#  set dscp cs3

C3750-E(config-pmap-c)#  police 32k 8000 exceed-action drop

 ! (VVLAN) Signaling is marked CS3 and policed to drop at 32 kbps

[Chris Deren · Accepted solution]

256kbps is perfectly fine, the idea is to keep it low which 256 on LAN is very low to prevent any worm, virus, etc from emulating voice traffic. In fact I use 256kpbs on my deployments as with built in bridge with G711 you reach 128kbps of payload.

HTH,

Chris

[wchatcher]

Chris,

Sorry for not replying before now.  That helped alot, thank you for your responce.

Thanks

Bill Hatcher

[Chris Deren]

NP, thank you for nice rating.

Chris