[NCLUG] Connectivity problems to ebay, (and possibly others)

[Evelyn Mitchell]

Is this likely to be a problem with Akamai (or whichever cacheing service
the upstream is using)?

Evelyn

* On 2005-12-27 13:59 John L. Bass <jbass at dmsd.com> wrote:
> Hi Guys,
> 
> For the last month I've been working to resolve a very interesting problem
> connecting to ebay (and I believe doubleclick and a few dns servers that
> cause SERVFAIL's from bind). Pages served from various servers hang till
> they timeout the browser, and then the browser retries with a different
> server. I've seen the problem mostly on various ebay servers, but also
> a similar problem with ads served by various other services (may be a
> different problem) - mostly doubleclick.
> 
> The problem is most likely a checksum or CRC failure in a router or load
> balancer between CWX and ebay's Denver connection. The problem changes with
> as little as the IP TTL field changing, and is easily changed by changing
> source IP addresses which cause a different subset of the following addresses
> to fail (sometimes intermittantly):
> 
>         root at fastbox log]# telnet 216.113.178.140 80
>         telnet: connect to address 216.113.178.140: Connection timed out
>         [root at fastbox log]# telnet 216.113.178.140 80
>         telnet: connect to address 216.113.178.140: Connection timed out
>         [root at fastbox log]# telnet 216.113.185.41 80
>         telnet: connect to address 216.113.185.41: Connection timed out
>         [root at test ~]# telnet 216.113.178.10 80
>         telnet: connect to address 216.113.178.10: Connection timed out
>         [root at Bass ~]# telnet 216.113.176.11 80
>         telnet: connect to address 216.113.176.11: Connection timed out
> 
> On several Class C's I've tested from, there are IPs which never seem to
> fail on any of these, some which fail on one or more every time, and
> others which only fail one out of ten connections or less. So it's something
> of a data pattern sensitive intermittant problem. The problem has been
> reproduced at our ISP's help desk intermittantly, which indicates to me
> that problem is broader than just our network connection.
> 
> For testing I've just telnet'ed to each of the above addresses, and if it
> connects, just hit return twice, and up arrow to run again about 5-6 times
> each. I've scanned about a dozen IP's on my class C and other machines in
> CWX on two different Class C's with similar results.
> 
> Our ISP has been unable to determine if the problem is with one of their
> routers, at the Denver NAP, or ebay -- and indication from them this morning
> is that we will just have to live with the problem since no one else is
> complaining, and ebay believes it's not their problem. The problem exists
> from our ISP with both Level3 and Cogent transport ... with the twist that
> the set of source IP's that work/fail changes ... indicating that as little
> as changing the TTL in the IP header provokes or avoids the failure, strongly
> suggesting a checksum/CRC hardware failure or possibly a hashing failure in
> a load balancer.
> 
> Try telneting to each of the addresses above a few times and let me know if
> you are also seeing the problem. If you are, call your ISP's help desk and
> report it too.  If they reply "no problem found", be persistant.  If you have
> more than one public IP address, try it from several. Have your friends and
> coworkers do the same.
> 
> Thanks,
> John Bass
> CWX.net
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Regards,                    tummy.com, ltd 
Evelyn Mitchell             Linux Consulting since 1995
efm at tummy.com               Senior System and Network Administrators
                            http://www.tummy.com/