Recently we added another Cisco Telepresence in our network (CTS 3000) and it gave me an opportunity to work on some QoS configs.

Cisco has a great reference for QoS with Telepresence and is a must read for anyone deploying Telepresence on the network.

[1] Cisco Telepresence SRND

I dealt with the QoS config in 3 different levels :: access, distribution, and WAN edge

At our access level, we use Catalyst OS and IOS in distribution and WAN edge. Refer to the SRND for the recommended values depending on Line cards being used. The example below is for 1p3q8t cards. To find out the QoS capabilities of the port use “show qos info runtime mod/port”.

Access config ::

! trust DSCP on port connecting to Telepresence

set port qos mod/port trust trust-dscp
set port name mod/port TP_CTS3000

! trust DSCP on uplinks

set port qos mod/port trust trust-dscp
set port qos mod/port trust trust-dscp

! config below applies to 1p3q8t line cards

set qos enable
set qos map 1q2t rx 1 1 cos 0-3
set qos map 1q2t rx 1 2 cos 4-7
set qos map 1p3q8t tx 2 cos 0
set qos map 1p3q8t tx 1 cos 1
set qos map 1p3q8t tx 3 1 cos 2
set qos map 1p3q8t tx 3 2 cos 3
set qos map 1p3q8t tx 4 1 cos 4
set qos map 1p3q8t tx 3 3 cos 6
set qos map 1p3q8t tx 3 4 cos 7
set qos wrr 1p3q8t 5 35 30
set qos txq-ratio 1p3q8t 5 35 30 30
set qos wred 1p3q8t tx queue 1 80:80 100:100 100:100 100:100 100:100 100:100 100:100 100:100
set qos wred 1p3q8t tx queue 2 80:100 100:100 100:100 100:100 100:100 100:100 100:100 100:100
set qos wred 1p3q8t tx queue 3 60:70 70:80 80:90 90:100 100:100 100:100 100:100 100:100
set qos cos-dscp-map 0 8 16 24 32 46 48 56
set qos ipprec-dscp-map 0 8 16 24 32 46 48 56

The Distribution config is very similar, but it’s based on IOS and applied at the interface level (also based on 1p3q8t)

Distribution config ::

! Global QoS configs
mls qos
mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos map ip-prec-dscp 0 8 16 24 32 46 48 56

! Uplink Interface level configs
inter gig m/p
! trust markings on uplink
mls qos trust dscp

! Set bw and weights on Q 1-3 and enable random detect on Q 1-3
wrr-queue queue-limit 5 35 30
wrr-queue bandwidth 5 35 30
wrr-queue random-detect 1
wrr-queue random-detect 2
wrr-queue random-detect 3

! limit PQ to 30%
priority-queue queue-limit 30

! 8 Drop thresholds (3q8t) on Q 1-3
wrr-queue random-detect max-threshold 1 100 100 100 100 100 100 100 100
wrr-queue random-detect min-threshold 1 80 100 100 100 100 100 100 100

wrr-queue random-detect max-threshold 2 100 100 100 100 100 100 100 100
wrr-queue random-detect min-threshold 2 80 100 100 100 100 100 100 100

wrr-queue random-detect max-threshold 3 70 80 90 100 100 100 100 100
wrr-queue random-detect min-threshold 3 60 70 80 90 100 100 100 100

! Map cos to egress queues (1-3 w/ thresholds)
wrr-queue cos-map 1 1 1
wrr-queue cos-map 2 1 0
wrr-queue cos-map 3 1 2
wrr-queue cos-map 3 2 3
wrr-queue cos-map 3 3 6
wrr-queue cos-map 3 4 7

! Map cos 4 and 5 to PQ
priority-queue cos-map 1 4 5

Finally, the WAN edge in our case goes out to the provider MPLS network. We change the markings from CS4 to CS5 as the carrier maps CS5 and EF to LLQ. It’s also remarked back to CS4 for ingress traffic from MPLS. It’s also very important to set the burst values correctly as Telepresence traffic can be very bursty. Refer to the SRND. I chose to use only certain QoS classes and set the bandwidth values according to interface speeds.

WAN Edge config ::

mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos map ip-prec-dscp 0 8 16 24 32 46 48 56

class-map match-any VOIP
descript for Voice media
match dscp ef

class-map match-any TELEPRESENCE
descript for Telepresence
match dscp cs4

class-map match-all NETWORK-CONTROL
descript for Routing
match dscp cs6

class-map match-all OAM
descript for Ops/Admin/Mgmt
match dscp cs2

class-map match-all CALL-SIGNALING
descript for Call-Signaling
match dscp cs3

class-map match-all MULTIMEDIA-CONFERENCING
descript for IP/VC
match dscp af41 af42 af43

class-map match-all TRANSACTIONAL-DATA
descript for Trans-Data
match dscp af21 af22 af23

class-map match-all BULK-DATA
descript for Bulk Data
match dscp af11 af12 af13

class-map match-all SCAVENGER
descript for Scavenger
match dscp cs1

policy-map CE-MPLS-EDGE
description T3 speed percentages
class VOIP
priority percent 10 ! PQ for Voice media
class TELEPRESENCE
priority percent 35 256000 ! PQ TP with 256KB burst
set dscp cs5 ! Mark CS4 to cs5 for SP MPLS LLQ treatment
class NETWORK-CONTROL
bandwidth percent 2 ! CBWFQ for Routing
class OAM
bandwidth percent 1 ! CBWFQ for Ops/Admin/Mgmt
class CALL-SIGNALING
bandwidth percent 2 ! CBWFQ for Call-Signaling
class MULTIMEDIA-CONFERENCING
bandwidth percent 10 ! CBWFQ for IP/VC
random-detect dscp-based ! DSCP-WRED for IP/VC
class TRANSACTIONAL-DATA
bandwidth percent 5 ! CBWFQ for Trans-Data
random-detect dscp-based ! DSCP-WRED for Trans-Data
class BULK-DATA
bandwidth percent 4 ! CBWFQ for Bulk Data
random-detect dscp-based ! DSCP-WRED for Bulk Data
class SCAVENGER
bandwidth percent 1 ! Minimum CBWFQ for Scavenger
class class-default
bandwidth percent 30 ! CBWFQ for Best Effort
random-detect

!————-

class-map match-any SP-TELEPRESENCE
descript Remark inbound cs5 from MPLS back to cs4
match dscp cs5

policy-map CE-MPLS-EDGE-IN
description used to mark inbound MPLS Telepresence cs5 to cs4
class SP-TELEPRESENCE
set dscp cs4
exit

Once applied to an interface, check your stats with a “show policy-map interface …” command. Queue drops can be checked to see if enough BW has been allocated to certain types of traffic. Drops would be expected in certain cases.

Ted