[c-nsp] shaper in policy-map is not taken into account
Martin T
m4rtntns at gmail.com
Wed Mar 19 07:09:02 EDT 2014
Velimir,
thank you for pointing this out! Based on "Understanding Queue Limits
and Output Drops on Cisco IOS Software
Platforms"(http://www.cisco.com/c/en/us/support/docs/routers/7200-series-routers/110850-queue-limit-output-drops-ios.html),
the default queue depth in case of pre-HQF is 64 packets for each
class. I was able to confirm this with "sh policy-map int" command and
also saw egress buffer drops in "sh int" output. Once I increased the
queue-limit to 4096 packets, the output drops disappeared.
Two other questions based on the "sh policy-map int" output seen below:
Service-policy output: SHAPER-INGRESS-TRAFFIC
Class-map: INGRESS-TRAFFIC-CLASS (match-all)
1141774 packets, 860950405 bytes
30 second offered rate 4520000 bps, drop rate 0 bps
Match: access-group name INGRESS-TRAFFIC-ACL
Traffic Shaping
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
19000000/19000000 118750 475000 475000 25 59375
Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 0 1141740 860947825 105341 127469015 no
Service-policy : VOIP-INGRESS-TRAFFIC-POLICY
Class-map: VOIP-INGRESS-TRAFFIC-CLASS (match-all)
0 packets, 0 bytes
30 second offered rate 0 bps, drop rate 0 bps
Match: access-group name VOIP-INGRESS-TRAFFIC-ACL
Queueing
Strict Priority
Output Queue: Conversation 264
Bandwidth 4500 (kbps) Burst 112500 (Bytes)
(pkts matched/bytes matched) 0/0
(total drops/bytes drops) 0/0
Class-map: class-default (match-any)
1141774 packets, 860950405 bytes
30 second offered rate 4520000 bps, drop rate 0 bps
Match: any
Queueing
Output Queue: Conversation 265
Bandwidth 14500 (kbps)Max Threshold 4096 (packets)
(pkts matched/bytes matched) 105341/127469015
(depth/total drops/no-buffer drops) 0/0/0
Class-map: class-default (match-any)
1512 packets, 97474 bytes
30 second offered rate 0 bps, drop rate 0 bps
Match: any
1) Am I correct that shaper applied in parent policy-map also shapes
all the traffic classes in child policy-maps, i.e. this 19Mbps shaper
is shared by three traffic classes: traffic in policy-map
VOIP-INGRESS-TRAFFIC-POLICY(it has "VOIP-INGRESS-TRAFFIC-CLASS" and
"class-default" classes) and traffic in policy-map
SHAPER-INGRESS-TRAFFIC(it has only "class-default" class besides
nested policy-map VOIP-INGRESS-TRAFFIC-POLICY).
2) How is the traffic classified in case of multiple classes and
nested policy-maps? Based on the example above, does it works in a way
that if traffic matches "INGRESS-TRAFFIC-ACL" access-list AND
"VOIP-INGRESS-TRAFFIC-ACL" access-list, then it's put into
"VOIP-INGRESS-TRAFFIC-CLASS" class? If traffic matches only
"INGRESS-TRAFFIC-ACL" access-list and not "VOIP-INGRESS-TRAFFIC-ACL"
access-list, then it's put into first default-class? Finally, if
traffic does not match "INGRESS-TRAFFIC-ACL", then it's put into last
default-class(the one which has 1512 packets at the moment)?
thanks,
Martin
On 3/14/14, Velimir Filipov <vfilipov at evolink.com> wrote:
>
> Hello,
>
> When the queues are full packet drop still occurs.
>
> So I suggest that there was a peak traffic at some point during that 30 sec
> period, which filled up the queue and resulted in dropped packets.
>
> You can increase the queue size or the conform interval to achieve lower
> drop rates for peak traffic, but might result in longer delays.
>
> Good luck.
>
> --
> Best regards,
> Velimir Filipov
> Network Administrator
>
>
> EVOLINK AD
> 86 Hristo Maksimov Str.
> 1111 Sofia, Bulgaria
>
> Phone: + 359 2 969 15 13
> Mobile: + 359 887 808 757
> Fax: + 359 2 9710 084
> Email: vfilipov at evolink.com
> www.evolink.com
>
> Thursday, March 13, 2014, 5:49:03 PM, you wrote:
>
>> Hi,
>
>> I have configured 20Mbps shaper("shape average 20000000") in
>> SHAPER-EGRESS-TRAFFIC policy-map under class-default traffic class:
>
>> В Service-policy output: SHAPER-EGRESS-TRAFFIC
>
>> В В Class-map: class-default (match-any)
>> В В В 306585 packets, 88611267 bytes
>> В В В 30 second offered rate 2107000 bps, drop rate 17000 bps
>> В В В Match: any
>> В В В Traffic Shaping
>> В В В В В В Target/Average В Byte В Sustain В Excess В В Interval
>> В Increment
>> В В В В В В В Rate В В В В В Limit В bits/int В bits/int В (ms)
>> В В В (bytes)
>> В В В В В 20000000/20000000 В 125000 500000 В В 500000 В В 25 В В
>> В В 62500
>
>> В В В В Adapt В Queue В В Packets В Bytes В В Packets В Bytes В
>> В Shaping
>> В В В В Active Depth В В В В В В В В В В В В Delayed В
>> Delayed В Active
>> В В В В - В В В 0 В В В В 306384 В В 88306481 В 6992 В В В
>> 9487573 В no
>
>> В В В Service-policy : VOIP-EGRESS-TRAFFIC-POLICY
>
>> В В В В Class-map: VOIP-EGRESS-TRAFFIC-CLASS (match-all)
>> В В В В В 0 packets, 0 bytes
>> В В В В В 30 second offered rate 0 bps, drop rate 0 bps
>> В В В В В Match: access-group name VOIP-EGRESS-TRAFFIC-ACL
>> В В В В В Queueing
>> В В В В В В Strict Priority
>> В В В В В В Output Queue: Conversation 264
>> В В В В В В Bandwidth 4500 (kbps) Burst 112500 (Bytes)
>> В В В В В В (pkts matched/bytes matched) 0/0
>> В В В В В В (total drops/bytes drops) 0/0
>
>> В В В В Class-map: class-default (match-any)
>> В В В В В 306585 packets, 88611267 bytes
>> В В В В В 30 second offered rate 2107000 bps, drop rate 17000 bps
>> В В В В В Match: any
>
>
>> During the last 30 seconds, policy-map has allowed traffic at 2.1Mbps
>> in average and dropped 17kbps in average. Why is my policy-map
>> dropping traffic while it should shape it? And shaping is configured
>> to 20Mbps not around 2Mbps..
>
>
>
>> regards,
>> Martin
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