Re: Question on LMP.

[Zafar Ali <zali@cisco.com>]

At 03:22 PM 4/15/2002 +0530, Manoj Sontakke wrote:
> Hi Jonathan,
>
> Thanks for the quick response. Please see my comments inline.
>
> Manoj
>
> Jonathan Lang wrote:
> > 
> > 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.
>
> Manoj-> The draft does not say so explicitly. Besides, all the
> LMP
> messages are IP encoded. So the routing table decides the outgoing
> interface for sending the LMP messages (any packet for that matter)
> depending upon the destination IP address.
>
> So is it possible to make such an association between the LMP
> control
> channel and a physical interface (though it is desirable)?

Hi Manoj, et all:

The association between the CC and
data bearer link is neither prevented nor enforced by the specification,
as you also mentioned. IMO, the association between the CC and data
bearer link is a vendor specific question. Vendors can manage the
available set of CCs in the way they would like to. I.e., a vendor may
choose a specific CC to send all messages that are pertaining to a data
bearer link, etc. The key is that the receiver node for the LMP messages
should be able to receive LMP messages from any CC that it’s running with
a given neighbor. This is of course with the exception of LMP Hellos
messages. 

> Are we
> deviating from the standard IP implementation
> ?

In selecting the CC by making an association between the CC and the data
link, one will NOT be diverting from IP. Specifically, one may consider
CC to be of two different types: interface bound or routed. E.g., SDCC/
LDCC based CCs can be regarded as interface bound IPCCs. LMP application
can select a specific egress interface while using interface bound CCs,
etc. 

Thanks

Regards… Zafar 

<snip>