[j-nsp] Interface Errors

[Kevin Oberman]

> Date: Tue, 3 Jun 2008 12:52:23 -0400 (EDT)
> From: Brendan Mannella <bmannella at teraswitch.com>
> Sender: juniper-nsp-bounces at puck.nether.net
> 
> 
> Hello, i have a M7i with a FE-4FE-TX, and i am seeing collisions on
> the interfaces. I am using two ports of the four, and both are showing
> the errors. I am also seeing some FIFO errors. Are these signs of a
> faulty PIC or should i not be concerned? Thoughts?

Looks fine to me. Collisions are NOT errors. They are a normal events
when Ethernet is running half-duplex. Since there are no CRC or framing
errors, which show up on duplex mis-match, I see nothing wrong except
that it is rare to need half-duplex these days. Is either of these ports
connected to a repeater? 

Repeaters are fan-out devices that don't do store and forward. They used
to be much cheaper than switches, but no one buys them these days and,
due to performance penalties, most people have long since replaced
them. If a repeater is used, all devices it connects to must be
half-duplex, but that is the only time half-duplex is normally
required. 

Another is an old Ethernet device that does not support full-duplex, but
these are VERY rare at 100 MHz speeds.

You probably can convert everything to full-duplex. That eliminates
collisions, but will not likely make any noticeable difference in
performance.
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751
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