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
where flows are defined via both L3 and L4 info, so
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
balancing traceroute probe 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.