At 07:58 AM 1/10/02, Madisa Ramagoffu wrote: >I have rephrased the question I have removed the F.F >and put the "following" coz thats what I meant when I said FF. FF is >not the address pls read again see if you will understand.Pls understand >as I am not good in speaking English > >This question is the same as like sending an ip packet with no >destination port number or something like that > >In a token ring environment a sender send a packet to a destination >with the following in a packet > >Everything specified excerpt the dsap >DSAP ???? >da specified >sa specified >SSAP specified > > > >The question . what will happen to the packet when it gets to the >destination if the DSAP is not specified???? >Is the packet going to be copied ? >Is the packet going to be dropped ? >Will it wait for the next packet or request a retransmit?? >What about the A C bit ?
I answered the entire question in my previous message. Maybe you did not read past my comment on FF. The gist of my message was that the receiver is going to process the message serially, one byte at a time. If the Frame Control field says that this is an LLC frame (with upper-layer data as opposed to MAC overhead data), then the recipient will assume that the byte following the Source Address (or Routing Info, if present) is a DSAP, whether that's what the sender intended or not. There's no such thing as AC bits. I think you are thinking about the Address Recognized and Frame Copied bits. Those get set at the MAC layer. They have nothing to do with LLC which handles DSAPs. A recipient station sets the address recognized bits at the MAC layer if it recognizes the frame is for it. The station sets the Frame Copied bits if it is able to copy the frame, which it should be able to do unless it doesn't have enough buffer space. (You may want to look into how a bridge behaves when it forwards frames. Should it set these bits?) I think you are remembering the question wrong. It doesn't make a lot sense. It sounds like you're trying to pass the CCIE written test without first getting a good grounding in networking fundamentals. Please don't contact me offline. This is the second time I've asked you not to. Please send questions to the list. Thanks. You should search for the Token Ring paper by Lou Rossi. It has been recommended by many people. It might help. Priscilla ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=31564&t=31564 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
