schemers@vela.acs.oakland.edu (Roland Schemers III) (10/17/90)
Hello! We are running Ultrix 4.0 on various machines:VAX 6000/310, DECsystem 5820, VAXstation 3100's, DECstation 3100's and DECstation 5000's. Someone suggested that we should have a -trailers option on our ifconfig command in rc.local. He said it ehances network performance. Here is part of the man page on ifconfig: trailers Enables the use of a trailer link level encapsulation when sending. This is the default. If a network interface supports trailers, the system, when possible, encapsulates outgoing messages in a manner that minim- izes the number of memory-to-memory copy operations performed by the receiver. -trailers Disables the use of a trailer link level encapsulation. By intuition it seems you would want trailers. Any comments? Thanx, Roland -- Roland J. Schemers III Systems Programmer schemers@vela.acs.oakland.edu (Ultrix) Oakland University schemers@argo.acs.oakland.edu (VMS) Rochester, MI 48309-4401 "So what's your pointer?" (313)-370-4323
treese@crl.dec.com (Win Treese) (10/17/90)
Disable trailers. Win Treese Cambridge Research Lab treese@crl.dec.com Digital Equipment Corp.
mathisen@dali.cs.montana.edu (Jaye Mathisen) (10/17/90)
In article <3411@vela.acs.oakland.edu> schemers@vela.acs.oakland.edu (Roland Schemers III) writes: >Someone suggested that we should have a -trailers option on our ifconfig >command in rc.local. He said it ehances network performance. > >By intuition it seems you would want trailers. Any comments? Somewhere, there was a large discussion about how the use of trailers wasn't supported by all implementations of TCP/IP, and it could cause all kinds of difficulties. While I don't remember the specifics, we used to run with trailers here and problems, that disappeared when we used -trailers. I would guess that if all you had were DEC machines running flavors of Ultrix, you could use trailers and not have a problem, but be wary when you mix vendors.
pavlov@canisius.UUCP (Greg Pavlov) (10/19/90)
In article <3411@vela.acs.oakland.edu>, schemers@vela.acs.oakland.edu (Roland Schemers III) writes: > Hello! We are running Ultrix 4.0 on various machines: ......... > Someone suggested that we should have a -trailers option on our ifconfig > command in rc.local. He said it ehances network performance. > > Here is part of the man page on ifconfig: > > trailers Enables the use of a trailer link level encapsulation > when sending. This is the default. .......... Your "somebody" was right in suggesting that you disable trailers (tho I doubt that you will see very much difference in network performance: your cpus outrun your ethernet cards by a wide margin). See mail on this issue two weeks ago: the trailers option is not all that standard anymore. Regarding the man page: its one of those man pages that should have been revised years ago, since (in this case) it was written when systems were much, much slower - in all respects. greg pavlov, fstrf, amherst, ny pavlov@stewart.fstrf.org