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Community Member

How do you tell if a 3750 switch is shaping traffic?

We have an Avaya PBX Medpro board plugged into a 3750 port with the following configuration:

interface FastEthernet1/0/4

description PBX Medpro-1

switchport access vlan 10

switchport mode access

duplex full

speed 100

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape 10 0 0 0

mls qos trust dscp

auto qos voip trust

Everything was working fine until the PBX call level went above 110 calls (G-711) which pushed the interface to more than 10mbps. When this happened random calls out of that medpro became garbled and after lots of troubleshooting we came to the conclusion that the default auto qos settings where the problem.

Default auto qos puts these statements on an interface:

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape 10 0 0 0

...which means that queue 1 will allow for 10mbps of traffic and then shaping will kick in.

Adding the line 'priority-queue out' to the interface disables the 10mbps limitation of queue 1 and instead forces the interface to process every packet that goes into the priority queue before anything else.

My question is - is there a 'show' command that we can use to see shaping at work? On router ports with a service policy that has shaping or policing on it you can see the shaping/policing in real time with 'show policy....'

What about on the 3750 switch ports?

2 REPLIES
Blue

Re: How do you tell if a 3750 switch is shaping traffic?

for the 3750, use the 'show mls ....' and the 'show policy-map...' qos commands to view the standard qos information.

please see the following link for more info:

http://www.cisco.com/en/US/products/hw/switches/ps5532/products_configuration_guide_chapter09186a00801eea0e.html#1021811

Community Member

Re: How do you tell if a 3750 switch is shaping traffic?

The 'sh mls qos...' commands do not tell me anything about the shaping or sharing part of the config. Here is the config of the switch port my medpro is connected to and then the output of 'sh mls qos int f1/0/17 statistics' which doesn't display anything about shaping or sharing.

interface FastEthernet1/0/17

description ROC-MPX

switchport access vlan 10

switchport mode access

duplex full

speed 100

srr-queue bandwidth share 10 10 60 20

srr-queue bandwidth shape 10 0 0 0

priority-queue out

mls qos trust dscp

auto qos voip trust

no mdix auto

spanning-tree portfast

end

ROC-SW55-15-MDF#sh mls qos int f1/0/17 statistics

FastEthernet1/0/17

dscp: incoming

-------------------------------

0 - 4 : 0 0 0 0 0

5 - 9 : 0 0 0 0 0

10 - 14 : 0 0 0 0 0

15 - 19 : 0 0 0 0 0

20 - 24 : 0 0 0 0 0

25 - 29 : 0 0 0 0 0

30 - 34 : 0 0 0 0 0

35 - 39 : 0 0 0 0 0

40 - 44 : 0 0 0 0 0

45 - 49 : 0 1574039946 0 0 0

50 - 54 : 0 0 0 0 0

55 - 59 : 0 0 0 0 0

60 - 64 : 0 0 0 0

dscp: outgoing

-------------------------------

0 - 4 : 14077591 0 0 0 0

5 - 9 : 0 0 0 0 0

10 - 14 : 0 0 0 0 0

15 - 19 : 0 0 0 0 0

20 - 24 : 0 0 0 0 571

25 - 29 : 0 0 0 0 0

30 - 34 : 0 0 0 0 0

35 - 39 : 0 0 0 0 0

40 - 44 : 0 0 0 0 0

45 - 49 : 0 1552631999 0 859946 0

50 - 54 : 0 0 0 0 0

55 - 59 : 0 0 0 0 0

60 - 64 : 0 0 0 0

cos: incoming

-------------------------------

0 - 4 : 1574071371 0 0 0 0

5 - 7 : 0 0 0

cos: outgoing

-------------------------------

0 - 4 : 14095863 0 0 571 0

5 - 7 : 1552631999 859946 1

Policer: Inprofile: 0 OutofProfile: 0

Notice the counters for the Policer are '0'. Shouldn't there be something in these counters since I have the 'priority-queue out' statement? With or without the priority-queue out statement, how do I tell that shaping is occuring? Again there is no policy map, just the two SRR statements that auto qos put on the interface.

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