At 06:29 PM 10/3/01, Lists Wizard wrote: >Hi Group, > >I am checking on the what the Certification Zone CD is saying about 802.3 >ethernet frames. Here is what they say: > >"Novell 802.3 raw frames do not use 802.2, so they do not have a protocol >identifier. In >practice, encapsulated IPX frames do have an hexadecimal FF in the first >byte, so the >protocol can be identified."
They missed the point that the IPX header immediately follows the 802.3 header with Novell raw. The first two bytes of an IPX header are a checksum. The checksum isn't used usually and has the value FF FF. It's two bytes and it is not a protocol identifier. Actually, Novell does have some implementations that use the checksum, but if it's used, then you can't use the raw frame format, because over the years software has come to rely on the FF FF following 802.3. Software uses that to recognize the frame format. Lots of other protocols can and do use 802.3. AppleTalk does, for example, (although it also uses SNAP). But the other protocols also use 802.2 which has a Service Access Point (SAP) that identifies the next layer. Anyway, since you have CertificationZone, please see the paper that I wrote on Troubleshooting Ethernet. It goes into gory detail on Ethernet frame formats. Priscilla >my questions are: > >What protocols other than novell can use the 802.3 frame? How are they >identified within the frame header? > >Any comments are welcomed > >Thanks > >Lists Wizard ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=21954&t=21945 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
