RE: Question on LMP.

[Jonathan Lang <jplang@calient.net>]

Manoj,
  Please see inline.

Thanks,
Jonathan

> -----Original Message-----
> From: Manoj Sontakke [mailto:manojs@sasken.com]
> Sent: Thursday, April 11, 2002 7:02 AM
> To: ccamp@ops.ietf.org
> Subject: Question on LMP.
> 
> 
> Hi,
> 
> I have two questions on LMP.
> 
> --------------------------------------------------------------
> -----------------------------
> 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 )] ?
Control channels are associated with interfaces.

> 
> --------------------------------------------------------------
> -----------------------------
> 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 ?
Message_ID helps identify new Config/ConfigAck messages for the same control
channel.

> 
> --------------------------------------------------------------
> ---------------------------
> 
> Any comments in this regard will be appreciated.
> 
> Thanks,
> Manoj
>