08-23-2010 05:10 AM - edited 03-06-2019 12:36 PM
Dear All,
please help me to understand , bandwidth sharing between LLQ and CBWFQ .
I have configured QOS with LLQ . one class is for strict priority and another class is bandwidth , last is default
I have 3mbps link . 1 mbps bandwidth I have configured strict priority . 1.5 mbps bandwidth, 512kbps for default class
consider strict priority class is totally empty , no traffic . and Bandwidth and Default class are fully choked ( 2mbps full) . is router allow to use strict priority class ??? even though it is completely nill usage . or it will not allow to use Strict priority bandwidth 1 mbps class .
Solved! Go to Solution.
09-17-2010 05:38 AM
Hi,
1),yes
2),yes
3),I guess you mean default class use business and premium class. The answer is yes.
4),For software based router, the default queueing is FIFO for GE interface. All classes share the link bandwidth.
HTH,
Lei Tian
08-23-2010 06:38 AM
Hi,
The queuing and scheduling might be little bit different on platform and code versions; in general, when there is no congestion on the link, any class of traffic can use all available bandwidth (unless there is policer for that class); during congestion, all class can use the guaranteed amount of bandwidth if needed, and they can share the rest available bandwidth base on their weight.
To your question, if the LLQ is empty other class can use the bandwidth assigned to LLQ.
Hope that answers your question.
HTH,
Lei Tian
08-23-2010 10:08 PM
Hi ,
when I configure the LLQ class and assign the bandwidth 1 mbps , as a strict priority . then policing will play a role . beow is configuration example .
In such scenario , is Strict priority class allow to pump traffic from other class , in its available free bandwidth
LLQ configuration exampls . total link capacity is 4 mbps .
Class VOICE_VIDEO_CLASS
Strict Priority
Bandwidth 1024 (kbps) Burst 512000 (Bytes) ---------------------------------------- 1 mbps ,no usage , strict priority configured
Class Hig-data-CLASS
Bandwidth 2048 (kbps) Max Threshold 64 (packets) -------------------------------------- completely choked , Bandwidth configured
Class class-default
Flow based Fair Queueing
Bandwidth 0 (kbps) Max Threshold 64 (packets) ----------------------- 1mbps completely choked ...
As what I understand , bandwidth class and default class traffic can allow to pump the traffic , but strict priority class will not allow to pump traffic to other class and either it will push its own traffic to other class . please suggest .
08-24-2010 03:34 AM
The LLQ/CBWFQ mechanism does not engage unless there is back pressure due to congestion. Any traffic can use all available bandwidth.
When there is back pressure, the PQ is serviced before any of the other CBWFQs.To prevent the PQ from starving out the CBWFQs, the PQ class of
traffic will be implicitly policed. So PQ cannot use other available bandwidth. If the PQ is empty, the bandwidth classes are allowed to use the bandwidth assigned to PQ based on their weight. There is no bandwidth reservation even it is called reserve bandwidth. Class-default is not subject to use available bandwidth if no 'bandwidth' configured on the class. Now that behavior has changed on HQF, because class-default has 1% bandwidth by default.
Please rate if it helps.
HTH,
Lei Tian
09-16-2010 11:41 PM
Thanks for the inputs . I have few more queries .
I have below scanarios
I have configured class name premium where voice and multicast traffic is marked and bandwidth reserved 10 mbps - precedence 5
Business class configure 20 mbps ( CBWFQ) - precedence 4 , default class - precedence 0 30 mbps
from your inputs its got clear if 10 mbps is fully utilized ( precedence 5) it will not utilize business class bandwidh ( CBWFQ )and default clas
2) Scanario : If Business class is completely choked ( 20 mbps), where i have configured below configuration .is it push the traffic to default class and premium class if there is free bandwidth available.
Class Business-Application-class
set precedence 1
bandwidth 20 mbps
3) Scanario : if default class 30 mbps is completely choked , premium class and business class nil utilized . is business class pump the traffic to premium class and business class .
4) Also I need understand . If I am marking only traffic at CE router and not allocating any bandwidth . how much by default it will allocate bandwidth for each class . below are the configuration and qos out put of each class . please help.
7200-IOR#sh policy-map MPLS-QOS
Policy Map MPLS-QOS
Class voice-video-control-class
set precedence 5
Class Business-Application-class
set precedence 1
Class class-default
set precedence 0
7200-IOR#sh class-map voice-video-control-class
Class Map match-all voice-video-control-class (id 2)
Match access-group 150
7200-IOR#sh class-map Business-Application-class
Class Map match-all Business-Application-class (id 1)
Match access-group 152
7200-IOR#sh class-map class-default
Class Map match-any class-default (id 0)
Match any
7200-IOR#sh policy-map interface gigabitEthernet 0/1
GigabitEthernet0/1
Service-policy input: MPLS-QOS
Class-map: voice-video-control-class (match-all)
690408597 packets, 66527045912 bytes
5 minute offered rate 58000 bps, drop rate 0 bps
Match: access-group 150
QoS Set
precedence 5
Packets marked 690408624
Class-map: Business-Application-class (match-all)
561255 packets, 70341513 bytes
5 minute offered rate 1000 bps, drop rate 0 bps
Match: access-group 152
QoS Set
precedence 1
Packets marked 561255
Class-map: class-default (match-any)
3801832539 packets, 1396390966707 bytes
5 minute offered rate 4024000 bps, drop rate 0 bps
Match: any
QoS Set
precedence 0
Packets marked 3801832565
09-17-2010 05:38 AM
Hi,
1),yes
2),yes
3),I guess you mean default class use business and premium class. The answer is yes.
4),For software based router, the default queueing is FIFO for GE interface. All classes share the link bandwidth.
HTH,
Lei Tian
09-30-2010 06:35 PM
Hi Thanks for the input ,
I need more help from you . I have 6509 core switch . where CEF is ruunning . I am applying QOS for the one of the application
where I am calling ACL and defining 1) perimit ip host 10.200.250.10 any
2) permit udp range 49000 49100 any
In clas-map OCS for the ACL i am marking ip precedence 5 . and applying on the interface
for the second statement of ACL i am finding hits , same time for the first statement ACL I am not finding ACL hits . As CEF being eanbled is that reason i am not finding hits at ACL at first statement and not marking the packets for precedence 5 . is there any way to check precedence 5 has been marked for the packetes . please suggest .
On the second scenario . for the above configuration . I am applying "service-policy output LLQ" on two interface .( both interface are connecting to my WAN router ) when I try to apply i got below error , is it makes any issue.please help .
6509-DC-Core(config)#int gigabitEthernet 5/2
6509-DC-Core(config-if)#service-policy output LLQ
QoS: Match criteria in class OCS on GigabitEthernet5/2 cannot simultaneously have match dscp | precedence | exp and match ACL
QoS: Match criteria in class OCS on GigabitEthernet5/2 cannot simultaneously have match dscp | precedence | exp and match ACL
6509-DC-Core(config)#int gigabitEthernet 3/6
6509-DC-Core(config-if)#service-policy output LLQ
QoS: Match criteria in class OCS on GigabitEthernet5/2 cannot simultaneously have match dscp | precedence | exp and match ACL
QoS: Match criteria in class OCS on GigabitEthernet5/2 cannot simultaneously have match dscp | precedence | exp and match ACL
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide