Subject: Questions on LDP-MIB entity configuration

From: Jim Sullivan <[email-masked]>
Date: Tue, 07 Dec 1999 09:11:21 -0500

I am looking for some clarification regarding 
the configuration of LDP entities. 
Please comment. 

I did an exercise where I tried to configure 
LDP entities communicating over several different 
types of interfaces( Ethernet, LCATM-PTPT, 
LCATM-NBMA, ATMGEN-PTPT, ATMGEN-NBMA).
I had the following questions. 

1. Section 3.1 in the LDP MIB states that each 
entry in the mplsLdpEntityTable will initiate an 
LDP session. This seems to imply that each peer 
that is reachable via a multi-access interface 
must be configured.
Is this correct ? 

I would think that for the case of a broadcast 
interface like Ethernet one would want to 
configure a single entity for all the potential 
peers on the interface. The entity configuration
would then be applied when establishing a session
to any peer that is discovered on the interface. 

On the other hand if the mult-access interface 
was of type LCATM-NBMA, then there would need to 
be an entity defined for each peer on that 
interface.    

For a ATMGEN-NBMA(an ATM interface using 
generic encapsulation) you may want to 
define an entity which is the default configuration
for all peers on the interface, that are not
explicitly configured.  

2. When configuring a LCATM-NBMA interface isn't 
it necessary to configure an entity for each 
peer on the interface ?  

One way to do this would be to configure the 
entity where one of the fields in the entry 
is the peers IP address. Similar to the case 
of an entity configured for extended discovery. 

3. When configuring an LDP entity for a LCATM-PTPT 
interface the indexing into the mplsLdpEntityTable 
is based on the LdpId, and the mplsLdpEntityIndex.  
Doesn't there need to be some way to correlate the 
entity configuration to the interface it is bound to ? 
I think you need to do this so that when a hello is 
received you can look up the configuration(i.e. the 
entity configuration)associated with the interface
the hello was received on.
Maybe the 2-byte label space identifier is the ifIndex ? 

4. What entities would I need to set up in order to  
configure one Ethernet interface to use per platform 
label space and downstream unsolicited label distribution, 
and to configure a second interface of type ATMGEN-PTPT, 
to use per platform label space and downstream on demand label 
distribution.   

It seems that there would need to be two entries in the 
Entity table. Each index would have the 
same LdpId because both are using per platform label space.
That means the mplsLdpEntityIndex is used to differentiate
between the two, but there is no correlation between this 
index and the interface. 
What am I missing here ? 

Thanks Jim