SDH/PDH and the OSI model

[Fred]

This might be a silly question but it does bug me. Where does SDH/PDH fit in
the model?
I'd say Layer 1. But since there sare some logical routing functions (VC)
and errordetection
maybe it has a place in Layer 2 as well.

Please elaborate on this one and give references if possible.

TIA
/Fred

[keep-it-clean]

I guess it is take home final exam time-of-year again.

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"Fred" <ir...@online.no> wrote in message
news:hR6K9.489$CG6....@news4.e.nsc.no...

[Yoram]

Hi Fred,

SDH/SONET fits into layers 1 and 2.

In general, layers 1+2 are the layers that defines connectivity between
DIRECTLY ATTACHED NE's.

Layer 1 defines the physical interface, bit rates etc, and layer 2 defines
the packet structure, the algorithms etc.

You can say that SDH has it's own "routing from the SDH point of view, but
for the end routers (in data network), it will still be a directly attached
connection.

You can get confused because of the fact that SDH carries other layer 2
protocols like ATM, FR and so on, but this is a common case in
communucations.

Yoram

"Fred" <ir...@online.no> wrote in message
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