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Community Member

Calling all WAN Experts: 7304 PXF Queue vs Interface Output Queue vs WRED

All,

I have a slighly congested link and while this is not too much of an issue, I would like to know the process of the following on a 7304 Interface.

I seem to have the following:-

A PXF Queue class class-default CBWFQ - Depth 128

An interface output queue - Depth 40

A WRED Queue - Depth upto 4096 ??

Now, because I have a PXF Queue, for each class within my policy-maps, is the interface output-queue (depth 40) not used?

Also, How does this relate to the WRED queue depth?

A couple of points to note:-

You can configure a WRED queue as follows :-

policy-map ken10

class ken10

bandwidth 10000

random-detect dscp-based

random-detect dscp 48 1 4096 65535

So queue depth can be upto 4096 I assume

Also, Please note the data below as you can see my PXF queue in times of congestion being filled up.

I would just like to know how this all fits in together.

At the moment, my thinking is this.

Packet arrives from input ring. There is congestion, so it fills up the PXF queue. As I see the PXF depth utilising higher that 40, ie I see 53, this is emptied, and placed onto the output interface queue. As this goes onto the Interface output queue, if there is more that 40 packets, tail drop will occur.

Not sure how WRED fits it to all of this thought.

Can any explain the flow for me please.

Kind regards,

Ken

Data below:-

WAN-ROUTER#sh int gi2/0/0

GigabitEthernet2/0/0 is up, line protocol is up

Hardware is SPA-2GE-7304, address is Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 47591390

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 8926000 bits/sec, 4896 packets/sec

30 second output rate 33941000 bits/sec, 6681 packets/sec

8433571569 packets input, 2260345731297 bytes, WAN-ROUTER#

WAN-ROUTER#sh pxf queue gi2/0/0

PXF queues for TIF 00016:

Class QID Depth/Max Drops

$ <crucial> 0 0/1024 0

$ carrier_voice 1 0/1024 0

$ carrier_video 2 0/1024 0

~ carrier_priori 3 0/128 0

~ carrier_bulk 4 0/128 0

~ class-default 7 46/128 0

Legend:

$: Priority Queue

~: RED Queue

WAN-ROUTER#

WAN-ROUTER#sh pxf queue gi2/0/0

PXF queues for TIF 00016:

Class QID Depth/Max Drops

$ <crucial> 0 0/1024 0

$ carrier_voice 1 0/1024 0

$ carrier_video 2 0/1024 0

~ carrier_priori 3 0/128 0

~ carrier_bulk 4 0/128 0

~ class-default 7 35/128 0

Legend:

$: Priority Queue

~: RED Queue

WAN-ROUTER#sh pxf queue gi2/0/0

PXF queues for TIF 00016:

Class QID Depth/Max Drops

$ <crucial> 0 0/1024 0

$ carrier_voice 1 0/1024 0

$ carrier_video 2 0/1024 0

~ carrier_priori 3 0/128 0

~ carrier_bulk 4 0/128 0

~ class-default 7 53/128 0

1 REPLY
Community Member

Re: Calling all WAN Experts: 7304 PXF Queue vs Interface Output

Also have attached the entire file for viewing :)

Regards,

Ken

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