[c-nsp] ME3600x buffer calculations- revisited
Julie Rudolph
Julie.Rudolph at cdw.com
Thu Dec 26 22:53:19 EST 2013
There is another troubling layer to this. I also need to traffic shape the egress traffic. But, I am unable to write the policies in such a way that when I apply the shaping, I also increase the queue limit.
So, here is one of *present* sample configurations that I'm working with:
----- SAMPLE CFG -----
policy-map CUST1-EGRESS-PARENT-PM
class class-default
shape average 10000000
service-policy CUST1-EGRESS-CHILD-PM
!
policy-map CUST1-EGRESS-CHILD-PM
class REAL-TIME-DSCP-CM
priority
police 8000000
queue-limit 2000000 bytes
class SIGNALING-DSCP-CM
bandwidth 1000
set dscp af31
queue-limit 2000000 bytes
class VIDEO-DSCP-CM
bandwidth remaining percent 10
class class-default
queue-limit 2000000 bytes
bandwidth 1000
----- END -----
The problem is that applying the traffic shaping uses the default queue-limit of 49152 bytes (see snippet below), but since it is not a leaf class, I cannot alter the queue-limit. So, when I send traffic down this interface, it is still hamstrung by that 49152 byte limit. I've tried a couple of configurations to try to address this (including those in http://www.gossamer-threads.com/lists/cisco/nsp/163596) but no configs I can come up with seem to address this. What am I missing? How can you shape traffic AND allow for higher queue-limit AND allow for a child policy? Since the traffic is stepping down from a 10gig input interface to a 100mb interface (which in turn needs to be shaped down to 10mb/sec), I definitely need something. And, since I'm dealing with voice traffic (udp), dropping packets doesn't alter the traffic stream (obviously). i.e. no tcp to back off the traffic.
----- SNIPPET----
ME3600X#show policy-map int gig0/2 output
GigabitEthernet0/2
Service-policy output: CUST1-EGRESS-PARENT-PM
Class-map: class-default (match-any)
7592059 packets, 1108656945 bytes
30 second offered rate 99000 bps, drop rate 0000 bps
Match: any
Traffic Shaping
Average Rate Traffic Shaping
Shape 10000 (kbps)
Output Queue:
Default Queue-limit 49152 bytes >>>>>> this seems to be the problem.
Tail Packets Drop: 0
Tail Bytes Drop: 0
Service-policy : CUST1-EGRESS-CHILD-PM
Class-map: REAL-TIME-DSCP-CM (match-any)
<CUT>
----- END SNIPPET -----
What am I missing??
Thanks much,
Julie
Julie Rudolph
From: Julie Rudolph
Sent: Thursday, December 26, 2013 4:12 PM
To: 'Waris Sagheer (waris)'; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] ME3600x buffer calculations- revisited
Great, thanks so much.
1) Was the dynamic allocation of buffers to the queues/classes that needed them always there, even in 12.2x code releases?
2) Could you oversubscribe the 18Mbytes in code prior to any 15.x release? I do not recall reading anything in the release notes about a change in the behavior such as this so I assume it was always there. (Sorry if I missed something in the docs.) So, perhaps the only limiting factor to how much burst or maximum throughput a port could handle had to do with the 491520 Bytes (pre-15.24S) per queue max. (If you couldn't oversubscribe the 18MB, then that would come out to a max of ~38 queues that could be maxed out to 491520 bytes).
3) I see now how the availability of the queue percent feature allows the ability of a queue to use more than the old (old = 15.2(4)S) max of 2Mbytes provided the resources are available. Not a question, just a comment. And a sigh of relief.
-Julie
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