01-02-2007 08:00 AM - edited 03-03-2019 03:13 PM
IOS Version 12.2(12a)
I need to implement QOS to Prioritize VOIP traffic.
Router has 2 interfaces
FastE 1
FastE 2
I have set up my Class map and policy map
I have tried to change class-default to fair-queue but nothing changes, it does not show in my config or when I do a show int.
Any sugestions on how to make this qos solution better?
Here is my config -
class-map match-any VOIP
match ip rtp 16384 16383
match access-group 100
match ip precedence 5
match ip dscp ef
!
!
policy-map qos-policy
class VOIP
set ip precedence 5
class class-default
!
!
!
!
interface FastEthernet0
description WAN
full-duplex
!
interface FastEthernet1
description LAN
full-duplex
service-policy input qos-policy
!
access-list 100 permit udp any any eq 5060
access-list 100 permit udp any any eq 5061
Thanks,
01-02-2007 09:21 AM
You can also use NBAR to prioritize traffic based on protocol instead of using access-list if your router is capable of handling it.
You marked packets as "ip precedence 5 and ef"...which means the same thing, just different field in the packet that's being marked. Use EF as the standard.
class-map match-any VOIP
match ip dscp ef
match ip rtp 16384 16383
match ip access-group 100
class-map match-any VOIP-Signaling
match ip dscp cs3
policy-map qos-policy
class VOIP
priority percent (of your bandwidth that you would like to designate for VOIP)
class VOIP-Signaling
bandwidth percent 5 (default as recommended by Cisco)
class class-default
bandwidth percent (of your bandwidth that you would like to designate for class-default)
random-detect dscp-based
By default, cisco wont' allow you to use more than 75% of BW, so you can use this command to override it (max-reserved bandwith 100) if you want, then apply the policy-map "service-policy output qos-policy" to your interface.
HTH,
hieu
Pls rate post if helpful.
01-02-2007 10:22 AM
When I am setting a percentage of bandwidth, what is that a percentage of? The 100mbs ethernet connection?
The WAN uplink goes into a wireless connection that is slower then 100mbs.
Thanks,
01-02-2007 10:55 AM
Friend,
It is better to apply QoS as an Output policy since it will prioritize the traffic on the slower interface.
Service-policy output
HTH, rate if it does
Narayan
01-02-2007 10:55 AM
In your case, that's the 100MBits ethernet connection of your FE1.
01-02-2007 11:04 AM
When you have a situation as you describe it really doesn't matter what you configure. QoS setting have little impact until you have caused a queue on the interface. Since you have a bottleneck past your router you will have problems long before your ethernet port becomes conjested.
You will need to cause a artifcial queue on your ethernet port to prevent the traffic from being send into your wan network too quickly.
Something like
policy shape
Class class-default
shape average 100000
service-policy QoS-policy
This cause it to first shape all traffic to a desired rate and then apply the service policy to that traffic after it is limited
01-02-2007 11:26 AM
Good to know, thanks Tim.
hieu
01-02-2007 11:41 AM
I may be completely wrong but i was under the impression that regaurdless of the utilization, prioritized packets still get transmitted first?
When you say
shape average 100000
do I adjust this value to the bottleneck rate?
Thanks,
01-02-2007 11:57 AM
In a way yes it does transmit them first but first implies there is more than one packet then you have a queue and QoS is in effect.
If a packet arives and the interface is idle it will be tranmitted immediately. If a voice packet now comes in it will not stop tranmiting the first packet and send the voice packet. On fast interfaces like this it makes no difference it is pretty mush fifo unless you get a burst of traffic.
Yes 100000 is just a random sample I used.
01-02-2007 06:28 PM
Ok, just so I understand correctly-
So if the link utilization is at 50% for a sustained period, QOS will still transmit priortized packets first before packets classified as class-default?
Thanks,
01-02-2007 07:20 PM
Also, when I create:
policy shape
Class class-default
shape average 100000
service-policy QoS-policy
I would then apply on my interface
( service-policy output shape ) ?
Both of my ethernet ports have a bottleneck on each side, what interface should I apply this policy to and what direction?
Thanks again,
01-03-2007 07:39 AM
hi,
i would also mark packets in the default-class with 1 or 2 or 3.
so it would not possible that a ip device (pc or whatever) sends pakets with ip prec=5 and goes into the voice queue
01-03-2007 09:23 AM
My new configuration -
(classification is done at the endpoints)
class-map match-any voip-signal
match ip dscp cs3
match ip dscp af31
class-map match-any voip-media
match ip dscp ef
!
!
policy-map qos-policy
class voip-media
bandwidth percent 75
class voip-signal
bandwidth percent 5
class class-default
fair-queue
policy-map shape-wan
class class-default
shape average 48800000
service-policy qos-policy
!
!
!
!
!
interface FastEthernet0
description WAN
bandwidth 48800
full-duplex
service-policy output shape-wan
!
interface FastEthernet1
description LAN
bandwidth 33000
There is a wireless link on both sides (lan) and (wan), should I be applying the policy to both interfaces?
I would want the default class marked with dscp 0 (best effort) I thought this was the default behavior?
Thanks,
01-04-2007 05:22 PM
Dan,
It's not neccessary that you've to apply the same policy to both FE0 and FE1. Just the FE0(WAN) will do, but also config it the same at the other end of the WAN link and monitor its performance from both ends.
Class class-default is already set at dscp 0 as the default setting.
hieu
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