[NCLUG] Connectivity problems to ebay, (and possibly others)
John L. Bass
jbass at dmsd.com
Wed Dec 28 02:35:51 MST 2005
I don't know which end the packets are being lost from, but rather believe
they are being lost on the way to ebay, the other side of Level3 and Cogent.
This theory is based on FRII's forced routing change from Level3 to Cogent
for one dest IP which changed the src/dest pairings for that dest IP. This
then strongly suggests the problem exists at the Denver NAP, or ebay (with
a small nagging question about the last FRII router in the path).
The only viable theory I have why this changed src/dest pairings is that
the TTL changed because of the number of hops. This theory is also consistant
with another theory that the observed randomness of paired src/dest connection
failings exists because of changes in the timestamp bits, the only other
uncontrolled variable in IP packet data.
If losses were due to the replies from ebay, that route would remain the same,
thru Level3 and one would expect the problem not to be affected by the forced
The theory of a forced web cache remains in question, but as Jeff noted, my
understanding too is the CWX is not behind FRII's web cache.
In addition, there is this free variable regarding problems which appeared at
nearly the same time, with web pages for ads also timing out ... mostly for
doubleclick url's, and partly due to DNS lookup failures returning SERVFAIL
for zones that I can reliably access all the servers for from my desktops.
If these are related to the ebay problem, then that points to the Denver NAP
routers, or possibly other services co-located with the same infrastructure
as the Denver gear serving ebay. However, so far the traceroutes for all
doubleclick services I've found don't have routes terminating at the Denver
NAP (which doesn't rule out a hidden ATM cloud between the visible end points
and Denver). So there might be two or three separate problems.
The most definiative failure would be a Non-FRII hosted machine, which would
move the finger to point clearly at the Denver NAP or Ebay. The second most
definiative test would be a completely clean (1-254) Class C outside FRII,
which passes a couple dozen connections to all four destination IP's at ebay,
with routes thru Level3 or Cogent terminating in Denver, which would point
the finger directly at FRII.
Any other ideas, theories, suggestions, comments?
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