Question on LMP.

[Manoj Sontakke <manojs@sasken.com>]

Hi,

I have two questions on LMP.

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Q1.  Control Channel Question

Assuming a configuration as shown.


                -----------------               -----------------
                |               |               |               |
                |            if1|---------------|if1            |
                |            if2|---------------|if2            |
                |     OXC 1     |               |     OXC 2     |
                |             d1|---------------|d1             |
                |             d2|---------------|d2             |
                -----------------               -----------------       
                
                
I have two OXCs connected by four links. Consider d1, d2 are configured
to carry data and 
if1 and if2 are configured to carry control data ( LMP messages and RSVP
and OSPF messages).

The LMP document defines control channels with an unique identifier (
control channel identifier ) between the negibouring nodes. So also, the
LMP messages are IP encapsulated.

Now, I have a couple of questions

1. Is there any association between the LMP control channels to the
physical interfaces( if1, if2). Because all the IP packets are routed on
the physical interfaces according to the routing table. The control
channel messages like  ( config and configAck etc.. ) can go on the any
physical interface which is decided by the routing table.

In such case, are the control channels a pure logical concept or do they
have any physical interface significance & correlation [ mapping between
control channles ( ccid ) and interfaces ( if1 and if2 )] ?

-------------------------------------------------------------------------------------------
Q2. MessageId question

In the LMP document, the config Message & config ack messages are
defined as 

        <configMessage> ::= <common header> <LOCAL_CCID> <MESSGAE_ID>
<LOCAL_NODE_ID> 			    <CONFIG>
        
        <configAckMessage> ::= <common header> <LOCAL_CCID>
<LOCAL_NODE_ID> <REMOTE_CCID> 				<MESSAGE_ID_ACK> <REMOTE_NODE_ID>

Assume the following sequence.

                                   ConfigMessage        
                OXC1    ---------------------------------->     OXC2

                                   ConfigMessage        
                OXC1    ---------------------------------->     OXC2

                                   ConfigMessage        
                OXC1    ---------------------------------->     OXC2

                                  ConfigAckMessage      
                OXC1    <----------------------------------     OXC2

On the OXC1 when the configAck Message is received then the OXC1 can
come to know that the config Message has been received by the OXC2 and
it can identify that it received the ack for a LOCAL_CCID. Any configAck
recevied will result in bringing that control channel UP.

So how does the <MESSAGE_ID> and <MESSAGE_ID_ACK> helps improve the
message realiability ?

-----------------------------------------------------------------------------------------

Any comments in this regard will be appreciated.

Thanks,
Manoj