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UUnet and CEF , was: Re: DNS and root servers

  • From: Kai Schlichting
  • Date: Mon Oct 25 12:25:11 1999

At 10:40 AM 10/25/99 -0400, James Smith wrote:

>Has anybody noticed any problems this morning with some of the root name
>servers?  (Particularly

No, but UUnet sure is funky today. Seems their load balancing with CEF is
broken again (like every 3-4 weeks), and it seems to occur between
EWR1 and routes more often than elsewhere.
General symptom: machines (local or remote) in the same subnets can/cannot
reach remote machines depending on whether the IP number (source or
destination) is odd or even, or the path (forward or return) to remote
machines is different depending, once again, on whether IP addresses are odd
or even. That leaves the question: how does CEF decide which circuit to
shove a packet into ?

3 ping runs from 3 separate, unloaded machines on the same subnet,
with the last octet of their IP's being .6 , .3 and .5)

--- ping statistics ---
55 packets transmitted, 55 packets received, 0% packet loss
round-trip min/avg/max = 481.775/528.385/586.649 ms

--- ping statistics ---
67 packets transmitted, 63 packets received, 5% packet loss
round-trip min/avg/max = 216.211/271.548/310.969 ms

--- ping statistics ---
62 packets transmitted, 62 packets received, 0% packet loss
round-trip min/avg/max = 83.303/130.738/174.111 ms

And the same machines (sequence preserved) pinging Netscape:

Message from [email protected] on ttyp0 at 12:16 ...
--- ping statistics ---
91 packets transmitted, 87 packets received, 4% packet loss
round-trip min/avg/max = 11.679/23.564/55.384 ms

--- ping statistics ---
84 packets transmitted, 84 packets received, 0% packet loss
round-trip min/avg/max = 209.768/241.706/270.967 ms

--- ping statistics ---
106 packets transmitted, 104 packets received, 1% packet loss
round-trip min/avg/max = 1637.63/1688.41/1722.27 ms

The same is true for a whole boatload of other sites (tested from a
UUnet-connected site as well as a Globix-connected site), whether they
are webservers with Local Director on the front end, or small 2501's
tucked away under someone's staircase.

Now try to explain that to a
UUnet "Did you power-cycle your router? It must be your telco's problem!" 
Customer Service person - I won't waste my time :)