At 09:14 AM 7/17/00, Stylen wrote:
>no, ethernet is always CSMA/CD. I believe AppleTalk uses CSMA/CA.
LocalTalk uses CSMA/CA. Hardly anyone uses LocalTalk these days. Most
people run AppleTalk on top of Ethernet (802.3), which, as you say, uses
CSMA/CD in a shared environment.
Here's what the 802.3 spec says about transmission: Monitor the carrier
sense signal and defer to passing traffic. When the medium is clear, frame
transmission is initiated (after a brief interframe delay to provide
recovery time for other CSMA/CD MAC sublayers and for the physical medium).
Here's what Inside AppleTalk says about the LocalTalk datalink layer:
LocalTalk attempts to minimize collisions by requiring transmitters to wait
for the duration of the interdialog gap plus a random period of time before
sending a frame.
It's the addition of a random period that makes LocalTalk collision
avoidance (CA) instead of just collision detection (CD). Ethernet waits a
random time after a collision.
Priscilla
>Richard Foltz, CCNP, CCDP, MCSE+I, Network+, A+
>Technical Solutions Consultant
>Sprint ENS
>
>
>"Luong, David" wrote in message ...
> >Further to your response, a fellow co-worker of mind has mentioned that
> >ethernet used CSMA/CD 802.3 instead of CA? Is it possible for ethernet
>media
> >to deploy both? I have not come across this before....any takers out there?
> >
> >Dave.
> >
> >-----Original Message-----
> >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
> >Sent: Monday, July 17, 2000 12:40 PM
> >To: Luong, David
> >Subject: Re: Deferred Packets
> >
> >
> >
> >
> >Deferred packets are a normal part of an ethernet transmission.
> >
> >If multiple hosts attempt to transmit over the same ethernet media at the
> >same
> >time, a collision occurs. After a specified period of time, both packets
> >involved in the collision are lost and must be retransmitted by the
> >transmitting
> >hosts. Ethernet interfaces employ collision-avoidance methods to detect
> >other
> >traffic on the network and await opportunities for safe transmission,this
>is
> >also known as ethernet deference.
> >
> >Hope this helps.
> >
> >
> >
> >
> >
> >
> >
> >
> >"Luong, David" <[EMAIL PROTECTED]> on 07/17/2000 01:37:57 PM
> >
> >Please respond to "Luong, David" <[EMAIL PROTECTED]>
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > To: "'Cisco Group Study'" <[EMAIL PROTECTED]>
> >
> > cc: (bcc: LOMBMML Hill Michale/Lincoln/Metromail)
> >
> >
> >
> > Subject: Deferred Packets
> >
> >
> >
> >
> >
> >
> >
> >
> >Hi Folks:
> >
> >On a 10-half ethernet connection between two routers, we are seeing
>deferred
> >packets happening as well as the normal usual collisions. Are deferred
> >packets just normal as well? Is it expected in ethernet media? Thanks in
> >advance...
> >
> >David Luong
> >CCNP,CCNA,Network+,A+,i-Net+
> >Telecommunications Analyst
> >Insurance Corporation of B.C.
> >Vancouver, B.C CANADA
> >
> >
> >
>
>
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