QoS - Class Based WFQ vs. WFQ on MPLS

[shaungiefer]

We are trying to determine our QoS strategy. Most of our WAN links are higher speed MPLS links, but there are a few slower F/R links.

I think there would be benefits to using CB WFQ on the F/R links, but is there a benefit to using it on the higher speed links? We want to prioritize voice and video traffic, but aren't sure there is a benefit on a fast ethernet interface.

Thanks in advance for your thoughts,

Shaun

[sundar.palaniappan]

Shaun,

If bandwidth isn't a constraint and if your router can quickly process those packets then technically there's no should be no need for QOS. With that said it doesn't hurt to enable QOS for real time traffic like voice/video as that would ensure those critical packets get priority over other not-so delay sensitive traffic like data during periods of congestion. For voice and video configure LLQ (priority queueing) and enable WFQ for all other traffic. Though you may have configured LLQ on the router it would only come into play when there's congestion on the network.

Here's a sample configuration for voice.

class-map match-all voice

match access-group 101

policy-map voice_qos

class voice

priority percent 50

class class-default

fair-queue

access-list 101 permit tcp any any eq 1720

access-list 101 permit udp any any range 16384 32767

int f0/0

service-policy out voice_qos

HTH

Sundar

[Pavel Bykov]

Hi Shaun.

Cisco were the first ones to discover the need for QoS in their high-speed LAN network. Whenever there are bursts of data, there can be disruptions of real time sensitive traffic, like Voice, even on the high speed links.

If your man-power capacity enables this, i would recommend enabling QoS.