Re: errors on my interfaces

From: Donald Becker (
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

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
Scyld Computing Corporation
410 Severn Ave. Suite 210 Second Generation Beowulf Clusters
Annapolis MD 21403 410-990-9993

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