Receive Queuing on 6500 Linecards

kfarrington · ‎03-26-2007

Guys,

Can someone help me here.

I am having a small problem understanding the importance of the receive queues within QoS.

So, You have all the following possibilities below.

But if a packet has arrived on a switchport (received), what do the receive queues do for you.

Lets say a Voice packet arrives with EF the same time as a HTTP packet with BE.

How does the rx queues work in this situation? Could someone let me know?

Its obvious with the TX queueing, you will transmit a better prioritised packet first, but the receive thingy is strange?

Many thx indeed,

Ken

Receive Queues

1q2t

One standard queue with two tail-drop thresholds

1q4t

One standard queue with four tail-drop thresholds

1q8t

One standard queue with eight tail-drop thresholds

2q8t

Two standard queues with eight tail-drop thresholds per queue

8q4t

Eight standard queues with four WRED drop thresholds per queue

8q8t

Eight standard queues with eight WRED drop thresholds per queue

1p1q4t

One strict-priority queue, one standard queue with four tail-drop thresholds

1p1q0t

One strict-priority queue, one standard queue with one non-configurable (100%) tail-drop threshold

1p1q8t

One strict-priority queue, one standard queue with eight configurable WRED drop thresholds and one non-configurable (100%) tail-drop threshold

kfarrington · ‎03-26-2007

also, looking at the cisco product specs, http://www.cisco.com/en/US/products/hw/switches/ps708/products_data_sheet0900aecd801459a7.html

None of the newer cards (DC cards not access) have any rx priority queues, only the old ones.

I assume the datacenter cards rely on receiving a frame from another switch's transmit queue which has been prioritised already? Would that be correct?

So, are receive queues nessecary atall?????? and where??????? High end servers only maybe? not user access?

Can anyone help? I have a big VoIP solution to look at and want to ensure the correct hardware is looked into, its all 6500 based.

Many thx,

Ken

ardenchen · ‎03-27-2007

for 6509, I think there is no congestions on any rx queues. congestions only happened on tx queues. you don't need deploy qos for rx queues at all. just think about the tx queues.

ardenchen · ‎03-27-2007

for 6509, I think there is no congestions on any rx queues. congestions only happened on tx queues. you don't need deploy qos for rx queues at all. just think about the tx queues.