This is true, but in a half-duplex environment, collisions dont' cause much of a performance drop, as when one side detects a collision, it will send a jamming signal to the other side so it will shut up and traffic can continue. If one side is half and the other is full, the jamming signal is ignored and the two will continue to try to talk over each other and traffic creaps to a halt. A device that is HD will clear the collision counter it generated every time a frame is successfully transmitted after a jam signal is sent, so you generally don't see collision counters on a HD device, if it is working in accordance to the ethernet specs. That's CSMA/CDs nifty little trick to keep you from panicking when you see your error counters in a network that is supposed to have collisions (well, not supposed to I guess, but *will* :-))
------------------ Aubrey Wells Senior Engineer Shelton | Johns Technology Group 404.478.2790 www.sheltonjohns.com On Sep 21, 2007, at 12:43 AM, Peter Wohlers wrote: > I guess thinking about it more, and in the spirit of not propagating > misinformation, collisions are normal in any half-duplex environment. > > Whether there's actually a mismatch or not is just how we're > conditioned to > view it because 100-half really doesn't buy you much but faster > collisions ;) > > Full duplex environments should by definition, not have any > collisions. > > --Peter > > Aubrey Wells wrote: >> I would have TWTC force their side to 100 Full, and you do the >> same on >> yours. Collisions, 99% of the time, only occur as a result of a >> duplex >> mismatch. >> >> * >> * >> *------------------* >> *Aubrey Wells* >> /Senior Engineer/ >> Shelton | Johns Technology Group >> 404.478.2790 >> www.sheltonjohns.com >> >> >> >> On Sep 20, 2007, at 7:10 PM, Jeff wrote: >> >>> >>> >>> On the 7206 the interfaces are FastEthernet interfaces >>> >>> I did try each one from auto to force, etc and did not seem to make >>> any difference >>> >>> But I was not trying to much. Till I asked some pointers >>> >>> Maybe its something I will have to have Timewarner match the >>> switch to >>> my ethernet card, no idea for sure >>> >>> Jeff >>> >>> >>> >>> >>> >>> -------------------------------------------------------------------- >>> ---- >>> *From:* Allan Leinwand [mailto:[EMAIL PROTECTED] >>> *To:* 'Jeff' [mailto:[EMAIL PROTECTED], >>> vyatta-users@mailman.vyatta.com >>> <mailto:vyatta-users@mailman.vyatta.com>, >>> vyatta-users@mailman.vyatta.com >>> <mailto:vyatta-users@mailman.vyatta.com> >>> *Sent:* Thu, 20 Sep 2007 17:36:42 -0400 >>> *Subject:* RE: [Vyatta-users] Errors On Outgoing Ethernet >>> Interface >>> >>> Hi Jeff, >>> >>> I'd guess that you're having an issue with the auto >>> negotiation >>> of speed and/or duplex on that interface. You can set these >>> commands as follows: >>> >>> vyatta <mailto:[EMAIL PROTECTED]># set interfaces ethernet eth0 >>> duplex ? >>> Possible completions: >>> auto Set duplex auto-negotiation mode >>> full Set full duplex mode >>> half Set half duplex mode >>> >>> I'd make sure you're set for auto on both speed and duplex >>> and >>> if that does not work I'd try to force the interface into a >>> setting that you know will work. "show interfaces" on your 7206 >>> can show you the current settings. >>> >>> Take care, >>> >>> allan >>> >>> >>> >>> -------------------------------------------------------------------- >>> ---- >>> *From:* [EMAIL PROTECTED] >>> <mailto:[EMAIL PROTECTED]> >>> [mailto:[EMAIL PROTECTED] >>> <mailto:[EMAIL PROTECTED]>] *On Behalf >>> Of *Jeff >>> *Sent:* Thursday, September 20, 2007 2:23 PM >>> *To:* vyatta-users@mailman.vyatta.com >>> <mailto:vyatta-users@mailman.vyatta.com>; >>> vyatta-users@mailman.vyatta.com >>> <mailto:vyatta-users@mailman.vyatta.com> >>> *Subject:* [Vyatta-users] Errors On Outgoing Ethernet Interface >>> >>> I finally got to do a test run on vyatta today for the 1st run. >>> >>> I have two ethernet interfaces setup one for lan the other >>> for the >>> wan connected to TimeWarner >>> >>> I unplugged my 7206vxr cisco >>> >>> And plugged in the two ethernet interfaces from it into my >>> vyatta box >>> >>> At any rate all seemed fine I could ping in and out, my >>> ipaddresses asgned were visable. >>> >>> All looked great, but then I logged into the vyatta web >>> interface, >>> and seen that the ethernet interface going to the wan >>> >>> to tme warner switch was poplulting errors in the amount of 5 >>> errors at a time every so many seconds >>> >>> At anyrate I viewed the interface and seen it was showing >>> colisions. >>> >>> The ethernet interface to the local lan had no errors at all. >>> >>> So after a little more runtime I plugged back into the cisco, >>> (No >>> errors) and all was totally fine again. >>> >>> Any ideas what may be causing these errors? >>> >>> I have built the vyatta on a Vision 1GHz Pent 3 with 1 gig >>> ram and >>> 80 gig harddrive (basically overkill) >>> >>> Anyway the two ethernet cards are built into the motherboard.. >>> >>> >>> >>> Jeff >>> >>> >>> >>> _______________________________________________ >>> Vyatta-users mailing list >>> Vyatta-users@mailman.vyatta.com <mailto:Vyatta- >>> [EMAIL PROTECTED]> >>> http://mailman.vyatta.com/mailman/listinfo/vyatta-users >> >> >> --------------------------------------------------------------------- >> --- >> >> _______________________________________________ >> Vyatta-users mailing list >> Vyatta-users@mailman.vyatta.com >> http://mailman.vyatta.com/mailman/listinfo/vyatta-users > > > -- > ***************** > * Peter Wohlers * > [EMAIL PROTECTED] > ***************** _______________________________________________ Vyatta-users mailing list Vyatta-users@mailman.vyatta.com http://mailman.vyatta.com/mailman/listinfo/vyatta-users
