The MPLS WG Archive

["Thomas D. Nadeau" <tnadeau@cisco.com>]

At 02:35 PM 7/30/2001 +0530, Apratim Mukherjee wrote:
>Hi Abhishek,
>
>         > if u look at the mplstunnelHopTable it's triply indexed.
> >mplsTunnelHopTableIndex is the first and mpldTunnelPathInUse is the >second
>index to that table. using these two indexes u get a list of hops >which is
>being used by this tunnel instance.
>
>Ya , you are right . But would not the values of the two indexes be the same
>for any tunnel instance , as Abhay also pointed out . If two indexes have
>the same value , wouldn't that mean a duplication ? Or is that the Hop Table
>could look like this :
>
>HopListLindex  PathOptionIndex HopIndex [ Hop Details ]
>         1                       1              1                ERO1
>         1                       1              2                   ERO1
>         1                       1           3                   ERO1
>         1                       2              4                   ERO2
>         1                       2              5                   ERO2
>         1                       2              6                   ERO2
>         1                       2              7                   ERO2
>
>         where the ERO1's denote the subobjects of the primary ERO
>         and ERO2's denote the subobjects of the secondary ERO ?
>
>         In the normal case then HopListIndex = PathOptionIndex always and
>also HopListIndex is a misleading name as it is the index to TWO hop lists
>and is not an unique identifier of a Hop List .

         If you have the same first two indexes, you
are indicating hops that are part of the SAME
path option. Any of the hops denoted by the third
index in this case are all considered to be part
of the same path option. What might be confusing is that
the description clause in the mplsTunnelHopTable has
not been updated to reflect the tertiary indexing.
We will update this as part of the IESG review of
the document.

         Incidentally, the purpose of having the indexes the
way that we do is to allow one to configure a tunnel
instance to have multiple paths (i.e.: what you were
referring to as path options before). For example, the
following demonstrates how one would configure two
paths for a particular tunnel:

         (mplsTunnelHopListIndex,
         mplsTunnelHopPathOptionIndex,
          mplsTunnelHopIndex ):          hop address

         -- first path option
         (1,1,1):        1.2.3.1
         (1,1,2):        2.3.4.1
         (1,1,3):        4.5.6.1

         -- second path option
         (1,2,1):        1.2.4.1
         (1,2,2):        5.6.5.1
         (1,2,3):        7.8.1.1

         ...


         --Tom




>         Thanks
>         Apratim
>
> > -----Original Message-----
> > From: Apratim Mukherjee [ mailto:ApratimM@netbrahma.com]
> > Sent: Saturday, July 28, 2001 7:02 PM
> > To: mpls@UU.NET
> > Subject: mplsTunnelHopTableIndex and mplsTunnelPathInUse
> >
> >
> > Hi,
> >
> > Could someone explain as to what is the difference between the
> > mplsTunnelHopTableIndex and mplsTunnelPathInUse objects in the
> > mplsTunnelTable . Dont they both point to an Explicit Route for the tunnel
> > ?
> >
> > Thanks,
> > Apratim
> >
> >