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What does this accomplish " PPP Multilink queue depth qos <number>" ?

Guys,

I have a router with 2 serials configure, they are both bonded with a multilink interface. I noticed a command under the "interface multilink 1" command, "ppp multilink queue depth qos 3".  What does this command do?

Thanks

BV

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Cisco Employee

Re: What does this accomplish " PPP Multilink queue depth qos <n

Hi,

I am not aware of a specific doc for this.

tx_limited = 1(2) << the number in the paranthesis is what I was referring to.

Yes, with qos (service-policy) applied, IOS will autmatically tune it down to 2 packets, per my earlier comment.

-Arun

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Re: What does this accomplish " PPP Multilink queue depth qos <n

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Cisco Employee

Re: What does this accomplish " PPP Multilink queue depth qos <n

Hello,

When you have qos configured, it takes effect only when there is "congestion" on the interface. Congestion is detected when the queue gets filled up. Having a lower queue depth is a good idea when you have RTP (Voice) type of traffic, so that QOS kicks in quickly to service the latency sensitive traffic. By default, when you apply a service-policy to the Multilink, the queue depth is 2 packets.

To take it further, you can do "sh controller | in tx_limit" and you will see this number reflected, when you have qos configured.

The default for FIFO is 8 packets.

HTH.

-Arun

New Member

Re: What does this accomplish " PPP Multilink queue depth qos <n

abaskara,

Is there any docs on this? I did issue show command you stated on the last reply. This is what I got:

chip_state = 2, ds->tx_limited = 0
  chip_state = 3, ds->tx_limited = 0
tx_limited = 1(2), errata19 count1 - 0, count2 - 0
tx_limited = 1(2), errata19 count1 - 0, count2 - 0

You stated "To take it further, you can do "sh controller | in tx_limit" and you  will see this number reflected, when you have qos configured", where is the 2 packets reflected? tx_limited = 1(2) or count2.

I did remove " ppp multilink queue depth qos 3" from the multlink interface. The above output is after I removed the depth command.

I do have a service policy with voip class maps on the multilink interface.

Thanks

Cisco Employee

Re: What does this accomplish " PPP Multilink queue depth qos <n

Hi,

I am not aware of a specific doc for this.

tx_limited = 1(2) << the number in the paranthesis is what I was referring to.

Yes, with qos (service-policy) applied, IOS will autmatically tune it down to 2 packets, per my earlier comment.

-Arun

New Member

Re: What does this accomplish " PPP Multilink queue depth qos <n

Thanks Arun,

This really helped out!!

Bobby

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