[e2e] Is RED dead?

[John Kristoff]

On Mon, 17 Oct 2005 14:32:02 +0800 (CST)
Jing Shen <jshen_cad at yahoo.com.cn> wrote:

> What do you mean by "DSCP are often enabled by default
> for some applications, such as  video"?  Would those
> routers can recognize  video traffic and set
> approprate DSCP to video packets?  Considering a

Some applications, particularly ones that do streaming video, set the
DiffServ codepoint to some AFxy value by default.  ...and if you have
QoS knobs turned on in your network gear, like simply 'mls qos' as on
the Cisco platforms as I've seen, you also get some basic handling of
those marked packets also.  In addition to putting EF marked packets
in a priority queue, AFxy marked packets are probably going into a
specific WRED queue and associated with a specific drop threshold.

> network carrying IPTV and normal traffic, could that
> be possible for each node to allocate/divide bandwidth
> to each class on each hop while balancing requirement
> between IPTV traffic and normal internet traffic?  

I'm not exactly sure what you're asking here.  If the question is,
can the routers allocate capacity, queueing behavior or something
else to different classes of traffic based on DiffServ codepoints
found in IPTV traffic versus other best effort traffic, then the
answer is yes.  If that was not your question, then please restate
and I'll try again.

> > In versions I've used, once you set 'mls qos'
> > globally, you get the
> > default queueing parameters as they are hard wired
> > to the physical
> > interface (modules).
> > 
> 
> do you mean WRED is enabled in those default queueing
> parameters? 

Yes if 'mls qos' is set.  For recent native IOS on a 6509 for example,
type:

  'show queueing interface g5/1'

It will tell your current queuing configuration and what queues
marked packets will be put in if QoS is enabled.

John