At 11:55 AM 6/13/01, Howard C. Berkowitz wrote:
>Lots of books are indeed wrong, when judged against the ISO Internal
>Organization of the Network Layer document. Stripping to a minimum
>of OSI speak, what we think of the network layer actually has three
>sublayers, one of which arguably extends into the data link layer or
>at least overlaps it.
>
>The Subnetwork Independent Convergence Layer is the truly
>link-independent part such as IP or CLNP.
>
>The Subnetwork Access Protocol is the interface to intelligent layer
>2 protocols that have payload identification -- X.25, ATM, LLC, etc.
Same SNAP that we have come to love and know on LANs? It seems to do
nothing except payload identification. It has five bytes: 3-byte vendor
code and 2 byte Type. Protocols with an Ethernet history put their
EtherType in the Type field.
I'm just checking my understanding. Thanks.
Priscilla
>The Subnetwork Dependent Convergence Facility maps between the
>Subnetwork Independent and Subnetwork Access parts. ARP goes here.
>
>Going a step farther, it's also worth considering the functional as
>well as layering models of B-ISDN/ATM, which identify the U(ser),
>C(ontrol)/signaling and M(anagement) planes at each layer. ARP is a
>C plane protocol between the end host and the ingress relay, much as
>is Q.931 and Q.2931. IP routing protocols, PNNI and SS7 are
>relay-to-relay M plane protocols.
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=8566&t=8335
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