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.
>Below you stated that LLC2 is diminishing because of the reliability of
>higher protocols such as TCP, however as I understand SNA does not use TCP
>and therefor you will always need LLC2 if you are running SNA.??????????
You can run SNA over TCP/IP. That's common too in some environments. The
obvious benefit is that it becomes routable.
>Can
>you please clarify or point me in the direction of a good book.
A lot of the design books and courses cover SNA, including mine. I'm just
asking questions now so I can get the history right. I was just getting
into computing when SDLC and HDLC were actually prevalent. But I was a
newbie. They wouldn't let me touch the WAN links. ;-)
>As I understand Netbios & SNA can be encapsulated in TCP ,& therefor use its
>connection orientated services & run over ev2 or 802.3SNAP. If you were
>implementing SNA & NETBIOS straight onto the wire would you then have to use
>LLC2 ( DO THESE PROTOCOLS HAVE TO RUN ON A CONNECTION ORIETATED TRANSPORT)
You don't HAVE to do anything. That's the nice thing about layers. A layer
offers services and a method for the next layer up to interface it. A
programmer takes advantage of this and hopefully offers some configuration
options for administrators also.
In answer to another post on this topic, the term NetBEUI is commonly used
to mean the NetBIOS session layer running directly on a data-link layer.
That method of using NetBIOS is diminishing. (It's not routable.) NetBIOS
over TCP/IP, aka NetBT and other names, is much more common these days.
Priscilla
>rgds. Chris.B
>
>
>
>Chris Burnham,
>Systems Engineer,
>Delphis Consulting Plc.
>Tel: +(44) 020 7916 0200
>Mob: +(44) 07799403576
>[EMAIL PROTECTED]
>
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
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