diffserv and qos

Unanswered Question
May 18th, 2007

Hi all, is diffserv the layer 3 marking of the packet, whereas 802.1p is the layer 2 marking ? and do we have to map these at between the layer 2/3 boundaries ?

I have this problem too.
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carl_townshend Thu, 05/31/2007 - 04:16


when i set the qos value on my switch for the port, If the pc or device does not set its own value say for a paticular application etc, how do i make the switch apply the qos value to the traffic to the incoming frames ?

royalblues Thu, 05/31/2007 - 04:28


If your switch supports the features, then you can always classify the packets based on IP address, port no etc, at the ingress and mark them as required.

eg. on a 3750 switch

ip access-list extended VOICE

permit udp any range 16384 32767

class-map match-all VOICE

match access-group name VOICE

policy-map VOICE-ACCESS

class VOICE

set ip dscp ef

interface fa 1/0/1

service-policy input VOICE-ACCESS

HTH, rate if it does


carl_townshend Thu, 05/31/2007 - 04:35

thanks for your help, I know im a pain but could you explain what each line does? so all we are doing here is creating an access list that defines port number etc, and if there are any matches it applies the ef policy to them? also say if we have a phone that already marks the packets, what would we do here

again , many thanks



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