>Thank-you to Howard, Rita, and others for their answers.
>
>At 05:22 AM 6/13/01, Burnham, Chris wrote:
>>Michael I am a bit confused.If you have SNA still on the network (which
most
>>big Corporates do) would you not be using Token Ring?
>>Can you run SNA over Ethernet using LLC2?
>
>Yes, running SNA over LLC2 and 802.3 is quite common. Many networks are
>transitioning from Token Ring to Ethernet, but they still have SNA.
>
>>why only LLC2 & not LLC1 or EV2 ??
>
>SNA implementations are typically written to interface to LLC2. Why?
>Perhaps because LLC2 is so similar to SDLC. It probably just made the
>coding easier. A side benefit is the reliability. A disadvantage, of
>course, is overhead.
Do not underestimate the extent to which IBM did things because they
were easier to code. Have you ever noticed that you can't use the
hex digits A-F in an IBM locally administered MAC address?
The normal assumption in SNA is that all remote devices activate only
when they are told to by the Master Controller (i.e., PU4 or PU5).
One exception, of course, had to be dialup access.
They reused the dialup access code for LAN stations, which also could
activate on their own. In reusing the code, they assumed that a MAC
address had the same format as a telephone number. Ever seen A-F in a
telephone number?
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=8510&t=8315
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