qos meanings

Unanswered Question
Dec 10th, 2008

Hi all, when we talk about qos, is things like priority queing / and say prioritizing certain dscp traffic a different thing ?

also what is the difference between EF and AF ?

Many thanks

Carl

Can anyone tell me this ?

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
Joseph W. Doherty Wed, 12/10/2008 - 05:18

"Hi all, when we talk about qos, is things like priority queing / and say prioritizing certain dscp traffic a different thing ?"

Likely different, yes. Priority queuing (PQ) might be a reference to one of the QoS methods provided by Cisco on some of their equipment. See http://www.cisco.com/en/US/tech/tk543/tk544/tk530/tsd_technology_support_sub-protocol_home.html. "prioritizing certain dscp traffic" would be a logical policy that could be implemented by one of several method, PQ being one, but so can CBWFQ prioritize DSCP marked traffic.

"also what is the difference between EF and AF ? "

Perhaps best explained by the RFCs that define them. See http://www.ietf.org/rfc/rfc2598.txt for EF and http://www.ietf.org/rfc/rfc2597.txt for AFxy.

carl_townshend Wed, 12/10/2008 - 06:26

so depending on what dscp value there is depends what kind of queing mechanism is used ?

what is low latency queing ?

cheers

Carl

Joseph W. Doherty Wed, 12/10/2008 - 07:40

"so depending on what dscp value there is depends what kind of queing mechanism is used ? "

No, although DSCP markings are often used by QoS mechanisms.

"what is low latency queing ? "

Special class used within CBWFQ. Packets in that queue are all transmitted before all "normal" queue traffic. Note, LLQ has an implicit policer when there's congestion.

Actions

This Discussion