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b2kzone-beniamin
Beginner

QoS Example, Config, Docs, ETC help

Hello,

 

So I will try to be short and precious.

 

First thing first I need doc or some resource from where I can learn and see different types of QoS and some examples,

 

Second I have a host --> SW --> Router and I want to apply QoS at the layer 2 and router, I have a cisco sw 2950 with 2 ports of 10gbits uplink and I want to now how to apply the QoS.

 

The last thing

 

I know that about the classification and marking and the best practice is to apply at the very beginning (in my case at the SW and when the packets leave the sw to go to router to be mark), also the policing, congestion management = queuring and concestion avoid but I can't find some example where to see the QoS in action 

 

What I want is to classify the traffic for voice, video, and browsing, priorities the voice and video from a wifi AP

1 ACCEPTED SOLUTION

Accepted Solutions

NB: I haven't studied the 2950 QoS, at least for some years, so my answers will be based on a quick scan of the documentation and/or how other older Cisco switches QoS worked.

#1 On older Cisco switches, once you enable QoS, incoming CoS/ToS were reset unless you explicitly trusted such markings or use an ingress policy.  If so, whether the need to do this was an option or a "must" depending on what you wanted to happen.

#2 Yes for using class-maps which may, optionally, use ACLs.  What you have posted appears to overlap if using "any" or redundant if using "all".

#3 What the policer is doing is marking traffic that's over 5 Mbps.

#4 and 5. Generally default mappers map banks of 8 DSCP values to/from CoS values.  Unless you wish to change the defaults, you don't need to use those commands.

#6, 7 and 8.  These command controls how queues are dequeued relative to each other and what markings are directed to which queues.  These too have default values.  Often the default tags to queue mappings don't need to be changed, but often how queues are dequeued, again relative to each other, may need adjustment.

For example CoS 0 and 1 may (by default) map (i.e. directed) to Q1, CoS 2 and 3 to Q2, CoS 4 and 5 to Q3, and CoS 6 and 7 to Q4.  Further all four queues (by default) may obtain an equal allocation of bandwidth (to each other).  I.e. two active queues would split bandwidth 50/50, three active queues would get one third each while all four active queues would get 25% each.

Now suppose you had VoIP traffic.  Often you want such traffic to have absolute priority to being dequeued first.  If your platform supported priority queuing (PQ), it might only support that on one specific queue, let's assume that's Q1.  Further assume such traffic is tagged with CoS 5.  So we enable PQ, map CoS 5 to Q1 and likely map CoS 0 and 1 to one of the other queues.

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5 REPLIES 5
Joseph W. Doherty
Hall of Fame Expert

Your question(s) are very broad.  Have you tried searching the Internet, or Cisco's main site?

BTW, QoS, for WiFi is rather "weak" and often WiFi devices don't support it.

Often VoIP or video will have issues, when there contention for bandwidth on WiFi.

hey, yes, yes, yes, I'm a man of yes :)))))

 

now I'm back to serious, I tried to search on internet, nada, nothing, void. on the other side on the cisco website the same nada, nothing, void probably because the switch is (end-of-life or end-of-sale)

 

the problem for me is with the switch I can't find some examples where to see how to confing my SW (2950T) with class-map, policy-map and service-policy, on the other side for my router I have a lots of docs, video, all kind of resource.

 

so to come back to the topic, let me tell you something about my network, I have few few devices connected to my SW all of the devices are connected via Access-Point, I want a example or a guideline of how to config my SW to apply the QoS for devices to priorities the video(youtube, live and other) voice(facebook call, skype, teams, others) and the rest of traffic.

 

I will put here some commands that I fond on the IOS and the version of IOS probably you se something that I don't

IOS vers: c2950-i6k2l2q4-mz.121-22.EA14.bin (C2950 Software (C2950-I6K2L2Q4-M), Version 12.1(22)EA14) is the las IOS for this SW

command that I have in the IOS for QoS:

#class-map ?
WORD class-map name
match-all Logical-AND all matching statements under this classmap

 

#class-map data-network

(config-cmap)#?
Calhoun QoS class-map configuration commands:
description Class-Map description
exit Exit from QoS class-map configuration mode
match classification criteria
no Negate or set default values of a command
rename Rename this class-map

 

(config-cmap)#match ?
access-group Access group
ip IP specific values

 

for policy-map

#policy-map ?
WORD policy-map name

 

(config-pmap)#?
Calhoun QoS policy-map configuration commands:
class policy criteria
description Policy-Map description
exit Exit from QoS policy-map configuration mode
no Negate or set default values of a command
rename Rename this policy-map
<cr>

 

(config-pmap-c)#?
Calhoun QoS policy-map class configuration commands:
exit Exit from QoS class action configuration mode
no Negate or set default values of a command
police Police
set Set QoS values

 

(config-pmap-c)#police ?
<1000000-1000000000> Bits per second (1M - 100M and multiple of 1M for FE ports; 8M - 1000M and multiple of 8M for Gig ports)

 

(config-pmap-c)#SET ?
ip Set IP specific values

 

and that's it, again the problem is with the SW I don't have any idea how to conf. the sw to classify and marking the traffic for what I want.

Ah, you're looking for QoS specific to 2950 switches, eh?

I recall, depending on the model they have a light (EI) to weak (SI) QoS feature set, at least compared to newer platforms.

Ideally what you want is the configuration guide for your switch model and IOS version and the chapter for QoS.

See if this helps: file:///C:/Users/12152/AppData/Local/Temp/P2_Qos%20en%20Catalyst%202950%20Switch.pdf

or

https://www.manualslib.com/manual/1287341/Cisco-Catalyst-2950.html#page=527-manual

or

https://www.cisco.com/c/en/us/support/docs/lan-switching/lan-quality-of-service/46523-2950qosfaq.html

hello again,

I write you back with half of understand and half of confusion, i will start from the beginning of the manual https://www.manualslib.com/manual/1287341/Cisco-Catalyst-2950.html#page=527-manual 

 

Starting with The chapter QoS and sub-chapter of Config Standard Qos

 

1. Do I need to "Configuring Classification Using Port Trust States" from QoS chapter ? if is an option or is a must ?

 

2. Classifying Traffic by Using Class Maps here I go the next things right ?

ip access-list VIDEO-VOICE-CALL

     permit udp 192.168.1.0 0.0.0.255 any dscp 46

     permit udp 192.168.1.0 0.0.0.255 any dscp 34

     permit udp 192.168.1.0 0.0.0.255 any dscp 32

class-map VIDEO-VOICE-CALL-CLASS

    match access-group name VIDEO-VOICE-CALL

    ip dscp 46 34 32

I define it the ACL and class map right ?

 

3. Classifying, Policing, and Marking Traffic by Using Policy Maps

policy-map VIDEO-VOICE-CALL-POLICY

     class VIDEO-VOICE-CALL-CLASS

     police rate-bps burst-byte [exceed-action {drop | dscp dscp-value}] this a line of comand that I don't understand what is doing

     police 5000000 8192 exceed-action dscp 10

     ip dscp 46 34 32

     exit

    exit

interface f0/2

     sw mode access

     service-policy input VIDEO-VOICE-CALL-POLICY (with this command i set the ingrees marking on the port and set the policy on the port)

untill here almost all is crystal clear , from here is the other half that confuse me

 

.4. Configuring CoS Maps do I must do this thing ?

mls qos map cos-dscp 8 8 8 8 24 32 56 56 (if I must do why? )

 

5. Configuring the DSCP-to-CoS Map

mls qos map dscp-cos 26 48 to 7 (if I must do why? )

 

6. Configuring the Egress Queues

Configuring CoS Priority Queues

wrr-queue cos-map qid cos1...cosn (if I must do why? and for what is this command)

 

7. Configuring WRR Priority

wrr-queue bandwidth weight1...weight4 (if I must do why? and for what is this command)

 

8. Enabling the Expedite Queue and Configuring WRR Priority

wrr-queue bandwidth weight1 weight2 weight3 0 (if I must do why? and for what is this command)

 

 

NB: I haven't studied the 2950 QoS, at least for some years, so my answers will be based on a quick scan of the documentation and/or how other older Cisco switches QoS worked.

#1 On older Cisco switches, once you enable QoS, incoming CoS/ToS were reset unless you explicitly trusted such markings or use an ingress policy.  If so, whether the need to do this was an option or a "must" depending on what you wanted to happen.

#2 Yes for using class-maps which may, optionally, use ACLs.  What you have posted appears to overlap if using "any" or redundant if using "all".

#3 What the policer is doing is marking traffic that's over 5 Mbps.

#4 and 5. Generally default mappers map banks of 8 DSCP values to/from CoS values.  Unless you wish to change the defaults, you don't need to use those commands.

#6, 7 and 8.  These command controls how queues are dequeued relative to each other and what markings are directed to which queues.  These too have default values.  Often the default tags to queue mappings don't need to be changed, but often how queues are dequeued, again relative to each other, may need adjustment.

For example CoS 0 and 1 may (by default) map (i.e. directed) to Q1, CoS 2 and 3 to Q2, CoS 4 and 5 to Q3, and CoS 6 and 7 to Q4.  Further all four queues (by default) may obtain an equal allocation of bandwidth (to each other).  I.e. two active queues would split bandwidth 50/50, three active queues would get one third each while all four active queues would get 25% each.

Now suppose you had VoIP traffic.  Often you want such traffic to have absolute priority to being dequeued first.  If your platform supported priority queuing (PQ), it might only support that on one specific queue, let's assume that's Q1.  Further assume such traffic is tagged with CoS 5.  So we enable PQ, map CoS 5 to Q1 and likely map CoS 0 and 1 to one of the other queues.

View solution in original post