From: Diment, Andrew (Andrew.Diment@qwest.com)
Date: Wed May 25 2005 - 13:16:29 GMT-3
From the Doc.
"An interface first removes the packets from the layer-3 queueing system and then queues them on the transmit ring. Service policies apply only to packets in the layer-3 queues and are transparent to the transmit ring."
The way I understand it is the "queue" and "ring" are proportional to each other...meaning changing one automatically changes the other. Or more specifically, when you change the TX-RING it automatically changes the TX-QUEUE.
As for your question 3. QoS is not applied to the tx-ring...only the tx-queue. Once a packet is in the tx-ring it waits to be transmitted. Say you have a 1000 packets in the tx-ring and a limit of 50 in the tx-queue. If the interface has Qos and a VOIP packet needs to get transmitted it comes into the tx-queue and get priority and put on the tx-ring. But now there are 999 packet in from of it so it will still be delayed. On the other hand, if you have 50 packets in the tx-ring and 1000 in the tx-queue that same VOIP packet would get put on the tx-ring (spot number 50) over the other 999 packets in the tx-queue.
I played with this once in real life for VOIP on an ATM interface with several VC's. It's mostly used there to try to speed up the physical transmittion of a "logical" subinterface.
HTH
Andy
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Mark Lasarko
Sent: Wednesday, May 25, 2005 10:51 AM
To: <Andrew Lee Lissitz; ccielab@groupstudy.com; Diment, Andrew
Subject: RE: tx-?-limit
Greetings Andrew & Andy, respectively
Unfortunately, the link offered was one of those that was not helpful to me.
Per my initial post, I already read all the ATM-PA stuff.
My questions are:
1) Why is the tx-queue-limit command automagically added?
(translation: when you issue tx-ring-limit this phantom command appears)
2) Why is the tx-queue-limit command unavailable directly?
(translation: it's not there in the command line)
3) What exactly do these commands do on non-PA interfaces?
(translation: I am a little slow and I still don't get it)
Thanx!
~M
>>> "Diment, Andrew" <Andrew.Diment@qwest.com> 05/25/05 11:37 AM >>>
I helps tweak QoS.
http://www.cisco.com/en/US/tech/tk39/tk824/technologies_tech_note09186a00800f
bafc.shtml
Andy
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Mark Lasarko
Sent: Wednesday, May 25, 2005 10:28 AM
To: 'GroupStudy'
Subject: tx-?-limit
Looking for other ways to tweak interfaces:
Rack1R1(config-if)#tx?
tx-ring-limit
Rack1R1(config-if)#tx-ring-limit 123
Rack1R1(config-if)#end
Rack1R1#sh run | b interface Serial0/0
interface Serial0/0
no ip address
encapsulation frame-relay
tx-ring-limit 123
tx-queue-limit 123
(note: tx-queue-limit is automagically added to the config)
I tried looking this up only to find some ATM-PA references that did not
clarify.
...Same commands (or lack thereof) appear to be true/available on ethernet,
etc...
I hope am clear in thinking this has nothing to do with the hold-queue in |
out command
(which defines the maximum # of input and output queues as I understand it)
That said, I am curious just what this does, if anything
And why we cannot do just a queue-limit?
(since that command does not exist??)
~M
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