Head is spinning after watching QOS video series

WastedYouth · April 2013

Hello. I just got done watching the CBT nuggets series on QOS. Here are some of the terms and oh boy a couple dozen more acronyms to squeeze into my waterlogged sponge of a brain:

DSCP
RED
WRED
Policing
Shaping
NBAR
Link Efficiency
TOS
COS
IP Precedence
Drop Precedence
MQC
AutoQOS
Priority Queuing
Low-Latency Queuing
WFQ
CBWFQ
Custom Queuing
FIFO
Class and policy maps
EF
AF
MLS QOS

I need to help implement QOS in a large enterprise environment in the next couple weeks, and I am struggling with making sense of all these topics. Since there seems to be SO many options here, I am basically looking for best practices. If someone could give me a basic plan to attempt to follow in doing this I would be ecstatic. If someone would dare to attempt to group some of these concepts for me as well that would be fantastic.

In my network we have a lot of VOIP from avaya phones, and video conferencing, and that's basically all the QOS I need to put in place. I'm leaning toward defining some simple NBAR class maps for shaping on all 56 branch office routers, and obviously on the core as well. Prioritize voice, then video, and leave data as best effort. Also I may want to put some kind of congestion management on the internet routers as well limiting http and https. My issue is there seems to be about 25 ways to do this!

My ideas could be way off base and if I would love suggestions and maybe some help making sense of all this.

For more info we have pretty newish gear, at least 2821s at all branch locations, and a lot of 3750x switch stacks.

Thanks so much for your time guys!

Corza · April 2013

Easiest way I have found is classifying it at switch level then prioritise. For example, when voice packet comes in, classify it as your highest, then it will send first.

On router match that DSCP value and specify a class map. Example,

!THIS MATCHES DSCP CS5 WHICH SWITCH HAS ALREADY SET THE DSCP VALUE ON!
class-map match-all VIDEO_QoS
description DATA_FROM_VLAN_7_(VIDEO)
match dscp cs5

!GIVE PRIORITY PERCENT!
policy-map QoS_POLICY
class VIDEO_QoS
priority percent 10

!PUT WHOLE POLICY MAP UNDER A SHAPING POLICY TO MATCH SERVICE PROVIDER WAN SPEED!
policy-map SHAPE_TRAFFIC_20Mbps
class class-default
shape average 20000000
service-policy QoS_POLICY

Don't forget to ask your service provider what DSCP markings they want used too.

I am self taught so some of it may be wrong but willing to accept some criticism to make it better.

aaron0011 · April 2013

Corza wrote: »

Easiest way I have found is classifying it at switch level then prioritise. For example, when voice packet comes in, classify it as your highest, then it will send first.

On router match that DSCP value and specify a class map. Example,

!THIS MATCHES DSCP CS5 WHICH SWITCH HAS ALREADY SET THE DSCP VALUE ON!
class-map match-all VIDEO_QoS
description DATA_FROM_VLAN_7_(VIDEO)
match dscp cs5

!GIVE PRIORITY PERCENT!
policy-map QoS_POLICY
class VIDEO_QoS
priority percent 10

!PUT WHOLE POLICY MAP UNDER A SHAPING POLICY TO MATCH SERVICE PROVIDER WAN SPEED!
policy-map SHAPE_TRAFFIC_20Mbps
class class-default
shape average 20000000
service-policy QoS_POLICY

Don't forget to ask your service provider what DSCP markings they want used too.

I am self taught so some of it may be wrong but willing to accept some criticism to make it better.

This is exactly the same method I use in most scenarios.

azaghul · April 2013

Check out the Cisco Design Zone

Cisco Validated Designs [Cisco Validated Design Program] - Cisco Systems

Most of the Small/Medium/Enterprise Branch Office Design Guides have a good section on QoS implementation. But also don't forget AutoQOS.

WastedYouth · April 2013

Corza wrote: »

Easiest way I have found is classifying it at switch level then prioritise. For example, when voice packet comes in, classify it as your highest, then it will send first.

One quick thing here: I thought shaping didn't involve marking or re-marking of any kind, or are you combining the two? Sorry I'm very green on this.

On router match that DSCP value and specify a class map. Example,

!THIS MATCHES DSCP CS5 WHICH SWITCH HAS ALREADY SET THE DSCP VALUE ON!
class-map match-all VIDEO_QoS
description DATA_FROM_VLAN_7_(VIDEO)
match dscp cs5

Ok, so I thought the TOS byte which includes the IP prec and drop prec simply said what priority to set the traffic at and NBAR would match that priority to a protocol or traffic type? Or in the unseen "VIDEO_QoS" map do you define this?

!GIVE PRIORITY PERCENT!
policy-map QoS_POLICY
class VIDEO_QoS
priority percent 10

With the command, "priority percent 10", is that priority queuing, or custom queuing or neither?

!PUT WHOLE POLICY MAP UNDER A SHAPING POLICY TO MATCH SERVICE PROVIDER WAN SPEED!
policy-map SHAPE_TRAFFIC_20Mbps
class class-default
shape average 20000000
service-policy QoS_POLICY

Ok I get this part. Thank you so much for your detailed and helpful reply!

Don't forget to ask your service provider what DSCP markings they want used too.I am self taught so some of it may be wrong but willing to accept some criticism to make it better.

You won't hear any from me

Thanks so much!

WastedYouth · April 2013

azaghul wrote: »

Check out the Cisco Design Zone

Cisco Validated Designs * [Cisco Validated Design Program] - Cisco Systems

Most of the Small/Medium/Enterprise Branch Office Design Guides have a good section on QoS implementation. But also don't forget AutoQOS.

Wow, there are so many good whitepapers to be found. This is definitely one of them. Thanks, I bookmarked it and will spend some time with it as things progress.

Head is spinning after watching QOS video series

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