yeah, basically what Bryan said. What happens without RED is that all your streams are going to slow down at once due to tail drop and TCP windowing. When things get non-congested again, they all ramp up again at once (global sync.). When your randomly drop packets, you are essentially making things work so that not all your streams ramp up all at the same time.
On Fri, Sep 4, 2009 at 2:14 PM, Bryan Bartik <[email protected]> wrote: > Edward, > > RED stops the global synchronization problem. That is when all sessions > scale back and then speed up at once. RED will cause a few sessions to scale > back, allowing most other flows to continue at the same speed. Like all QoS > mechanisms, it's not going to resolve all bandwidth issues, but should be > able to alleviate some problems where large flows aree causing congestion. > WRED (weighted RED) uses the DSCP bits to differentiate further. > > -hth > > On Fri, Sep 4, 2009 at 12:03 PM, Bodnar, Edward > <[email protected]>wrote: > >> I have a general question. If TCP packets are dropped causing a slow >> down on a network ( Tail drop ) If I enable RED and it starts randomly >> dropping packets before the congestion happens how does this help me. I >> keep reading answers that say it drops the packet before the congestion >> starts but it’s still dropping packets how does this help? >> >> >> >> Ed, >> >> >> >> >> >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> >> > > > -- > Bryan Bartik > CCIE #23707 (R&S), CCNP > Sr. Support Engineer - IPexpert, Inc. > URL: http://www.IPexpert.com > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > -- Regards, Joe Astorino - CCIE #24347 R&S Technical Instructor - IPexpert, Inc. Cell: +1.586.212.6107 Fax: +1.810.454.0130 Mailto: [email protected]
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
