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RE: Rapidly-variable routing on the time scale of seconds to minutes?

  • From: Charles Shen
  • Date: Mon Jan 31 22:19:22 2005

> On Mon, Jan 31, 2005 at 09:59:39PM -0500, Charles Shen wrote:
> [ snip ]
> > 
> > >From the responses, the answer to "the rapidly-variable routing on 
> > >the time
> > scale of seconds to minutes" seems to be:
> > 
> > 1. It could be link layer load balancing, with the two interfaces 
> > belonging to the same router. 2. It could be per-flow load 
> balancing 
> > where flows are defined via both L3 and L4 info, so 
> traceroute probe 
> > could not reflect the truth.
> > 
> > My question is then: would it be safe to argue that the above two 
> > causes explain all (or most of?) the observed "fluttering" routers? 
> > (some examples listed below)  What we are concerned about is 
> > per-packet load balancing (packets in the same flow go through 
> > different paths), which will cause trouble to protocols 
> that install 
> > state information in routers along the flow path.
> 
> AFAIK, multiple routers showing up in a single-hop in 
> traceroute response is a sign of packet-by-packet load 
> balancing, not flow based.
> 
> I could be wrong, though this was my past observation.
> 
> P.S.: What router-interacting applications are you using?
> 

I am talking about e.g. QoS reservation signaling applications.





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