The MPLS WG Archive

[Ina Minei <ina@juniper.net>]

	Please find below a few comments/questions on this mib.

			Thank you,

				Ina

1) Problem expressing a situation where no frr is configured on any interface

mplsFrrConfIfs OBJECT-TYPE
       SYNTAX        Unsigned32
       MAX-ACCESS    read-only
       STATUS        current
       DESCRIPTION
         "Indicates the number of MPLS interfaces configured for
          protection by the FRR feature, otherwise this value
          MUST return 0 to indicate that LSPs traversing any
          interface may be protected."
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
       DEFVAL { 0 }
       ::= { mplsFrrScalars 5 }

The defval = 0 is misleading in this case. If I have no frr on any of
the interfaces, there is no way for me to express that, unless the
descrioption should say "may not be protected".

Same for
 mplsFrrActProtectedIfs OBJECT-TYPE
       SYNTAX        Unsigned32
       MAX-ACCESS    read-only
       STATUS        current
       DESCRIPTION
         "Indicates the number of interfaces currently being protected
          by the FRR feature if mplsFrrConstProtectionMethod is set to
          facilityBackup(2), otherwise this value should return 0 to
          indicate that LSPs traversing any interface may be protected.
          This value MUST be less than or equal to mplsFrrConfIfs."
       DEFVAL { 0 }
       ::= { mplsFrrScalars 6 }



--------------------

2) Confusion regarding the values of oneToOneBackup and
   facilityBackup.

mplsFrrDetourIncoming
"The number of detour LSPs originating at this PLR if
         mplsFrrConstProtectionMethod is set to oneToOneBackup(1).
         This object MUST return 0 if the mplsFrrConstProtectionMethod
         is set to facilityBackup(2)."

>From this I understand that the values are oneToOneBackup(1),
facilityBackup(2).

However, the definition is different:

mplsFrrConstProtectionMethod OBJECT-TYPE
       SYNTAX        INTEGER { oneToOneBackup(0),
                               facilityBackup(1)

The same values of 1 and 2 appear in the description of other
variables, such as mplsFrrDetourOutgoing.

Also I was wondering why "none" was not a valid value for
mplsFrrConstProtectionMethod, it would seem to make sense as well.

-----------------------

3) Notifications

Do we really want to have notifications emitted with msec granularity?

mplsFrrProtected
mplsFrrUnProtected

The way these two are currently defined, it will be very hard to
correlate protect/unprotect traps, and indeed it is not
guaranteed that the unprotect trap will be sent.
The least we could do is to require that if you sent a protect for
a particular tunnel, make sure to send the unprotect. This is after
all just one trap.

>From previous experience with lsp up/down traps, what customers
want is to be able to correlate the events. The rate limiting that is
applied creates havoc in this correlation. But a simple mechanism can
be set in place to ensure the correlation in the software.

Perhaps an operator will also comment on this.

---------------------
4) Question - Properties of mplsFrrConstEntry

mplsFrrConstEntry OBJECT-TYPE
       SYNTAX        MplsFrrConstEntry
       MAX-ACCESS    not-accessible
       STATUS        current
       DESCRIPTION
         "An entry in this table represents detour LSP or bypass tunnel
          setup constraints for a tunnel instance to be protected by detour
          LSPs or a tunnel.

          Agents must allow entries in this table to be
          created only for tunnel instances that require fast-reroute.
          Entries indexed with mplsFrrConstIfIndex set to 0 apply to all
          interfaces on this device for which the FRR feature can operate
          on."

Why do we want to have the properties of the tunnel instance instead
of the constraints for the tunnel itself?

-------------------
5) Question on the tunnel index

 mplsFrrConstTunnelIndex OBJECT-TYPE
       SYNTAX        MplsTunnelIndex
       MAX-ACCESS    not-accessible
       STATUS        current
       DESCRIPTION
         "Uniquely identifies a tunnel for which fast reroute is
          requested."
       ::= { mplsFrrConstEntry 2 }

    mplsFrrConstTunnelInstance OBJECT-TYPE
       SYNTAX        MplsTunnelInstanceIndex
       MAX-ACCESS    not-accessible
       STATUS        current
       DESCRIPTION
         "Uniquely identifies an instance of this tunnel for which fast
          reroute is requested.

         - lower 16 bits : protected tunnel instance
         - higher 16 bits: must be all zeros"
       ::= { mplsFrrConstEntry 3 }

mplsFrrConstTunnelIndex OBJECT-TYPE - what would be the required value here?


----------------
6) Question on protection type

 mplsFrrConstProtectionType OBJECT-TYPE
       SYNTAX        INTEGER { none(0),
                               linkProtection(1),
                               nodeProtection(2)
                             }
       MAX-ACCESS    read-create
       STATUS        current
       DESCRIPTION
         "Indicates type of the resource protection."
       DEFVAL { nodeProtection }
       ::= { mplsFrrConstEntry 4 }

Why do we have the value of "none" defined here? Isn't this for an
entry that represents either a detour or a bypass? Then how can there
be no protection?

--------------
7) Typo (sorry of nitpicking)
mplsFrrTunARHopEntry  OBJECT-TYPE
       SYNTAX             MplsFrrTunARHopEntry
       MAX-ACCESS         not-accessible
       STATUS             current
       DESCRIPTION
         "This entry contains fast-reroute protection status of a signle
                                                                 ^^^^^^^

-------------------
8) Question on mplsFrrLogEntry

It seems we have two choices - no logging or log until reaching the
limit. Why not also have an option for wrapaournd ? What is the value
of holding on to old log entries forever? Would an operator comment of how
this is used? Wouldn't the nms pick up the values from here and store them
remotely?

---------------
9) Questions on One2one backup

We don't have a variable that specifies the bw on the detour. Don't we
need one?

There are no notifications for the 1-to-1 backup. Wouldn't we want to
track when an lsp starts using the detour and when it stops using it?