Re: errors on my interfaces

From: Donald Becker (becker@scyld.com)
Date: Fri Jan 04 2002 - 09:42:21 EST


On Thu, 3 Jan 2002, Madhav Diwan wrote:

> Hey .. can someone clarify this:
>
> If i send a ping packet or any other packet out to a network where my
> interface is UP but not plugged into anything with a cable, should i
> get an error on the interface when i look at an ifconfig command ?

Perhaps, but not certainly.
It depends on the media type and transceiver.
   With many types of fiber transceivers, no.
   With 10base2 transceivers, always.
   Twisted pair transceivers often have a non-standard mode to ignore
    link beat, but will usually report transmit attempts with no link
    beat. In some cases this will not be reported immediately.

> How else can i get recieve and trasmit errors?

Many, many ways. Check out a good Ethernet "MIB".
 Everyone knows about Rx CRC and length (runt and oversize) errors.
 Most know about Tx out-of-window collisions and 16-collision.
 Some of the less obvious error types are heartbeat, dribble bits, and
 framing/symbol errors. Rx and Tx jabber detection, and IFG
 over-shrinkage...

Other error information that doesn't fit naturally into counters:
 Some 10base2 transceivers can estimate the distance to a short or open
 Some 100baseTx transceivers can estimate the distance to the link
 partner or a bad cable kink.

Other types of failures are internal to the NIC or driver, such dropped,
FIFO and ring errors are also counted.

Donald Becker becker@scyld.com
Scyld Computing Corporation http://www.scyld.com
410 Severn Ave. Suite 210 Second Generation Beowulf Clusters
Annapolis MD 21403 410-990-9993

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