10-29-2009 08:08 PM - edited 03-06-2019 08:23 AM
expert
I am currently trying QoS for video conferencing,
And the main protocol of video conferencing is H.323, current setting on the port which end point plugged in is: (cat3750)
interface FastEthernet1/0/6
description testing
switchport access vlan 10
switchport mode access
switchport voice vlan 110
switchport port-security maximum 2
switchport port-security
switchport port-security aging time 1
switchport port-security violation restrict
switchport port-security aging type inactivity
srr-queue bandwidth share 10 10 60 20
srr-queue bandwidth shape 10 0 0 0
priority-queue out
mls qos trust device cisco-phone
mls qos trust cos
auto qos voip cisco-phone
macro description cisco-phone | cisco-phone
spanning-tree portfast
spanning-tree bpduguard enable
service-policy input AutoQoS-Police-CiscoPhone
end
basically autoQoS from cisco.
Can I get advice on?
1. Is above base QoS from Cisco including video conferencing? If not, what I should include? And how can I do it?
2. If I have 1G Ethernet link for a WAN do I need QoS on WAN interface? If I do, what I should do? If it is cat6500, will it cause performance issue? What about if wan router is cat3750?
Sorry for the silly question, Could anyone help me?
Any comments will be appreciated
Thanks in advance
Solved! Go to Solution.
10-30-2009 01:42 AM
You will need the port to trust dscp from the video-device: mls qos trust dscp
A phone wil not be connected so you may remove the phone-qos settings.
You will also need to map the corresponding dscp value to a cos value.
Mostly this is CS4 - cos4 which is a default value but check it anyway.
You must also verify that there is sufficient bandwidth reserved for CS4 traffic in the WAN.
regards,
Leo
10-30-2009 01:42 AM
You will need the port to trust dscp from the video-device: mls qos trust dscp
A phone wil not be connected so you may remove the phone-qos settings.
You will also need to map the corresponding dscp value to a cos value.
Mostly this is CS4 - cos4 which is a default value but check it anyway.
You must also verify that there is sufficient bandwidth reserved for CS4 traffic in the WAN.
regards,
Leo
10-30-2009 02:49 AM
great thanks for help.
Could you please advice me how can I check if the map is CS4 - cos4?
Many regards
11-02-2009 04:45 AM
To see the switch mappings between Cos/IP Prec/DSCP you need to use the "sh mls qos maps ..." command -
As for trusting DSCP, as Leo suggested it all depends on whether you trust the end device or not. It's important to establish a trust boundary and often this is done on the first ingress switch where you classify and mark/remark the traffic.
Bear in mind if you trust DSCP and a user could disconnect the device and attach their pc and mark their packets with the correct DSCP value then their traffic would get preferential treatment. And the traffic would not need to be video traffic as you are only looking for a DSCP value and then trusting it.
Only you really know how likely, how much of a threat that would be in your network.
Jon
10-30-2009 03:32 AM
sorry, I forgot mention one thing, that the video conferencing is third party equipment. So, I should be still trust dscp, right?
11-02-2009 04:34 AM
That is one option. In most cases trusting is an acceptable solution because of its simplicity.
It provides the easiest way to differentiate packets as long as the user is unable (or incapable) to manipulate the qos levels.
If the latter is seen as a potential risk, you may choose to rewrite dscp values using class maps or acl's.
regards,
Leo
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