Cell Relay Archive

[Manish Kumar <manish@npi.stpn.soft.net>]

I think I agree with all the derivations and values you have arrived at.
Seems to be OK to me.

Srikrishna wrote:

> Here I go again with PNNI. Please bear with me while I am exposing my
> total ignorance. It is not easy reading the PNNI spec. Hence the
> example
> below.
>
> I have a physical switch which is made up of two logical nodes. One of
>
> them is the "lowest level node" and the other is the "Logical group
> node". The functions of both these node are implemented in the same
> physical switch.
>
> Let us say,
>
> The "lowest level node" part is identified as AESA address A.2.x.y
> where
> A is 12 bytes, 2 takes up 1 byte, x is 6 bytes (ESI of the physical
> switch which implements the lowest level node function)  and y = 0 is
> 1
> byte (SEL) for a total of 20 bytes.
>
> The "logical group node" part is identified as AESA address A.2.x.1
> where A again is 12 bytes, 2 takes up 1 bytes, x is the same 6 bytes
> (ESI of the physical switch whihc implements the LGN function) and y =
> 1
> is 1 byte (SEL) for a total of 20 bytes.



> Before I continue, Is the above theory correct or am I already screwed

> up?
>
> Anyway, assuming I am correct,

A.2.x.0 and A.2.x.1 is OK for lowest level node AESA and logical group
node AESA respectively.


>
>
> Peer group ID of the lowest level node = 104.A.2 where 104 is the
> level
> of the peer group of which this "lowest level node" is a member of.
>
> Node ID of the lowest level node part = 104.160.A.2.x.0 for a a total
> of
> 22 bytes
>
> where 104 is the level of the "lowest level node's" containing peer
> group which is 13 bytes (made up of A.2), 160 indicates that this is
> the
> "lowest level node" and the remaining 20 bytes is the AESA address of
> the "lowest level node" as indicated before.
>
> Peer group ID of the LGN = 96.A where 96 is the level of the peer
> group
> of which this LGN is a member of.

PG ID of 104.A.2 and 96.A is also OK.


>
>
> Node ID of the LGN = 96.104.A.2.x.0 for a total of 22 bytes
>
> where 96 is the level of the LGN containing peer group which is 12
> bytes
> (made up of A), 104 indicates that it is a LGN of the peer group whose
>
> level is 104 and the remaining 20 bytesis the AESA address of the
> "lowest level node" as indicated before.

Node IDs are OK.


>
>
> As one can see that the AESA addresss are different for both the
> "lowest
> level node" and the LGN parts even though they are in the same
> physical
> switch. This difference is in the SEL value (o for lowest level node
> and
> 1 for the LGN) as dictated in section 3.3.1 on page 19.

That's right as per af-pnni..... section mentioned by you.


>
>
> The LGN needs a AESA address obviously to setup an RCC SVC between
> which
> may or may not be directly connected. Why does the "lowest level node"
>
> need its own unique AESA address? Is it because it may need to setup
> SPVC/SPVP other than that I do not see the need from a signalling
> point
> of view
>

But as said in 3.3.1 the AESA for LGN is derivable from the AESA of the
lowest level node. So, this is one immediate necessity that I can think
of - for the definition of a base address from which LGNs can get their
address by making incremental changes.

It is also required in the derivation of node identifiers (for both
lowest level nodes and LGNs).

So, I think it is justified for the lowest level node to have its own
unique AESA.


>
>
> Also the peer group ID's and the Node ID's are different as required.
> Am
> I correct that when the AESA address and the level information are
> configured into the switch, the peer group ID's and the node ID's are
> automatically generated.

Yes, once the AESA and level is configured - peer group IDs and node IDs
need not be set explicitly.
They default to certain values based upon the AESA and the level (Look
up Annex F).


>
>
> Can you confirm if I have derived these #' sabove correctly given the
> initial AESA addresses.

> How I am doing so far?. Now my main Q.
>
> Even after talking out the above example out loud, I am not sure the
> real need for a node ID.
>

I am myself working on the requirements and the necessity for nodeIDs.
I agree with you that its a difficult doc to read and assimilate.


> Thanks for all the help in advance..
>
> Srikrishna..
>
> PS : The above represent my personal views NOT that of my employer.



I am speaking solely for myself.

Regards,
Manish Kumar