08-27-2009 02:23 PM - edited 03-04-2019 05:52 AM
Hi.
I have the following problem.
A Client with a main and a remote site entering to an MPLS network. I have consistent QoS politics and we have voice traffic (precedence 5, priority queue) with not delay variation in the delay when congestion occurs. But when the video traffic circulates (prec 4, bandwitdh command) the delay in this traffic increases when cogestion occurs. Is this behavior normal? how can to avoid this behavior?
thanks.
08-27-2009 02:59 PM
Hi,
what kind of Queuing does class Video traffic has?
If its CBWFQ, then yes, as Bandwidth is guranteed, but delay is not Guranteed. If its delay sensitive, Configure LLQ for that class of traffic.
HTH
Mohamed
08-27-2009 04:06 PM
Video is offen very variable in its bandwidth demand. It's possible your CBWFQ bandwidth statement provides enough bandwidth for your video's average bandwidth demand, but not enough to prevent queuing bursts. You could try increasing the bandwidth allocation. (Your video won't use any more average bandwidth, but a higher allocation means bursts are less likely to queue relative to other traffic.)
Another possible solution might be moving/converting the video to an LLQ class.
PS:
Since you mention MPLS, much can also depend on what your MPLS provider guarantees for IP Prec 4 traffic.
08-27-2009 04:08 PM
Hi there Pedro,
Can you post the QoS and interface configs?
Thanks,
Brad
08-28-2009 12:33 PM
(CE)-1-(PE)-2-(P)-3-(PE)-4-(CE)
(CE)1 (fast ethernet interface)
policy-map Shaping_Datos_FE
class class-default
shape average 3072000
service-policy QoS_Out
policy-map QoS_Out
class 6CoS_Prec5
priority 256
police cir 256000 bc 48000 be 96000
conform-action set-prec-transmit 5
exceed-action drop
class 6CoS_Prec4
set ip precedence 4
police cir 768000
conform-action transmit
exceed-action drop
class 6CoS_Prec3
bandwidth 512
set ip precedence 3
class 6CoS_Prec67
bandwidth 16
class 6CoS_Prec2
bandwidth 256
set ip precedence 2
class 6CoS_Prec1
bandwidth 256
set ip precedence 1
class class-default
set ip precedence 0
(PE)1 (Gigabit ethernet 100 Megas)
policy-map SHAPING3M
class class-default
shape average 3072000
service-policy CE
policy-map CE
class prec5
priority
police cir percent 9 (cir 276000 bps)
conform-action transmit
exceed-action drop
class prec4
bandwidth percent 25 (768 kbps)
class prec3
bandwidth percent 17 (522 kbps)
class prec2
bandwidth percent 9 (276 kbps)
class prec1
bandwidth percent 9 (276 kbps)
class prec67
bandwidth percent 1 (30 kbps)
2,3 10 GIGA LINKS WITH 10 PERCENT OF UTILIZACION AT MUCH
(PE)4
interface ATM0/0.5 point-to-point
description ROUTER 1841 BASICO - MAQUETA MPLS
bandwidth 1024
ip vrf forwarding vpn_12956_10000
ip address 10.19.10.22 255.255.255.252
no ip directed-broadcast
no atm enable-ilmi-trap
snmp trap link-status
pvc MQT 4/32
vbr-rt 1153 1153
encapsulation aal5snap
service-policy in QoS_In_ATM0/0.5
service-policy out QoS_Out_ATM0/0.5
policy-map QoS_Out_ATM0/0.5
class prec4
bandwidth percent 25
class prec5
police cir percent 10 conform-action transmit exceed-action drop
priority
class prec3
bandwidth percent 20
class prec2
bandwidth percent 15
class prec1
bandwidth percent 5
class prec67
bandwidth percent 2
(CE)4
map-class frame-relay FR_Out
frame-relay cir 1024000
frame-relay bc 10240
frame-relay mincir 1024000
service-policy input QoS_In
service-policy output QoS_Out
policy-map QoS_Out
class 6CoS_Prec5
priority 128
police cir 128000 bc 24000 be 48000
conform-action set-prec-transmit 5
exceed-action drop
class 6CoS_Prec4
set ip precedence 4
police cir 128000
conform-action transmit
exceed-action drop
class 6CoS_Prec3
bandwidth 128
set ip precedence 3
class 6CoS_Prec67
bandwidth 16
class 6CoS_Prec2
bandwidth 96
set ip precedence 2
class 6CoS_Prec1
bandwidth 128
set ip precedence 1
class class-default
set ip precedence 0
08-28-2009 02:55 PM
Some suggestions:
You might want to define an explict bandwidth allocation for your IP Prec 4 class.
You might want to stop using (implicit) FQ within class-default.
You might need to tune your shapers, either smaller Tc and/or define less bandwidth (to allow for L2 header bandwidth).
Questions:
PE4 shows 1 Mbps Vbr-rt and CE4 shows 1 Mbps frame-relay? If these two interconnect you need to allow for the bandwidth difference between ATM and frame-relay (ATM uses more bandwidth because of cell header overhead and cell padding). Also, what's the max bandwidth of the frame-relay link since w/o a shaper (I believe) it's limited by the physical interface not CIR setting.
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