05-29-2012 05:13 PM - edited 03-04-2019 04:30 PM
Hi All,
I am working with a client to implement QoS for their Lync environment. Lync 2010 has this feature to mark dscp values based on packets tagged with logical ports. As an example, packets on port 49000 til 49999 will be marked to dscp 46(ef).
On Cisco 2811 router, I am basically honouring the markings by the application and placing bandwidth priority on them and sending it out to the WAN.
The behaviour that I notice is that when port based packets are marked with a certain dscp value on the application, the router policy map doesn't pick up any packet increment for that dscp. But when all packets without port assigning to it are marked with certain dscp value, I can see increment on the router policy map for that dscp match.
Why is this so???
The client wants the Lync to mark the packets with dscp value and the router is suppose to honour the marking, schedule the priority and send it out.
Pls see below for my config:
class-map match-any QOS-SCHED-CRITICAL
match ip dscp ef
class-map match-any QOS-SCHED-FLASH
match ip dscp af31
match ip dscp af32
class-map match-any QOS-SCHED-FLASHOVERRIDE
match ip dscp af41
match ip dscp af42
match ip dscp af43
!
!
policy-map QOS-QUEUE-OUT
class QOS-SCHED-CRITICAL
priority percent 25
class QOS-SCHED-FLASHOVERRIDE
bandwidth remaining percent 40
class QOS-SCHED-FLASH
bandwidth remaining percent 30
class class-default
bandwidth remaining percent 30
random-detect dscp-based
!
interface FastEthernet0/1
description xxx
bandwidth 12000
ip address xxx
ip accounting output-packets
duplex full
speed 100
service-policy output QOS-QUEUE-OUT
Any help witll be appreciated.
05-29-2012 05:34 PM
Hello,
Couple of questions for a thread start:
1) Are you sure that Lync do correct port based marking - I gues sit is worth doing of sniffer (SPAN) on the switch connected to 2811 router and examine those packets
2) What is the config of the incoming port of 2811. You showed only outgoing fa0/1.
Nik
05-29-2012 05:46 PM
On question 1: Yes, we have verified that with Wireshark. It shows dscp marking done based on ports that has been set.
Question 2: I am only applying QoS on outbound traffic. There's no requirement for inbound traffic.
05-29-2012 06:00 PM
First of all I would recomend that packets with correct marking are actually coming to router input interface.
You can apply ACL below to watch it:
access-list 101 permit udp any any dscp ef
access-list 101 permit ip any any
or the one below to see logs with packet details
access-list 101 permit udp any any dscp ef log-input
access-list 101 permit ip any any
Then we can consider the rest output policies.
Nik
05-30-2012 12:17 AM
Thanks Nik. I'll do that.
The other things is that the Lync client is connected to a switch, and then to a router. I am only doing QoS on the router and not on the switch. Do I need to set anything on the switch to honour the dscp markings based on ports?
05-30-2012 07:08 PM
well, if switch has mls qos enabled - then the port connected to Lync client should trus the dscp marking coming from it (mls qos dscp trust) That is to reserve marking without it switch will drop precedence to 0.
Nik
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