The MPLS WG Archive

[Arthi Ayyangar <arthi@juniper.net>]

Hi,

I have some questions regarding the traceroute mode.

1)
In the Downstream Mapping, there is a field 'Downstream IPv4 Router ID'
that is basically the router ID of the nexthop node, of a valid recipient
of an MPLS echo request. It is assumed that every node knows what the
nexthop 'router ID' for an incoming label is. Is this always true?
Wouldn't it be enough to fill in just the interface address
if the interface is numbered?

2)
In section 4.2, it says

   "If the echo request contains a Downstream Mapping TLV, L MUST further
   check whether its Router ID matches one of the Downstream IPv4 Router
   IDs; and if so, whether the given Downstream Label is in fact the
                                ^^^^^^^^^^^^^^^^^^^^^^^^^
   label that L sent as its mapping for the FEC...."


  From this it seems that we are only verifying the contents of the TLV
(Downstream Label). Don't we care about the actual incoming label that the
echo request arrived with ?

Thanks,
-arthi