The MPLS WG Archive

["Vijayanand C" <vijayc@hclt.com>]

Hello,
Regarding the LSR MIB, the use of InSegmentNpop is not clear to me and I
raised this issue earlier, but have not got a reply. If for a particular
label 'N' pop operations are always done then what is the significance of
the N-1 labels beneath it. Which scenario is this useful and how is the 'N'
value set,especially when it is greater than 1.

Regards,
Vijay

-----Original Message-----
From: Vipul Sharma [mailto:vsharma@senecanetworks.com]
Sent: Tuesday, June 12, 2001 11:59 PM
To: davari@ieee.org
Cc: mpls@UU.NET
Subject: RE: LSR-MIB Question


Shahram,
	I had run into similar question a while ago...Attached is the
info. which
will help you for 1.
My feeling is that since there is no error conditions maybe they need to
be
collected in mplsInSegmentDiscards. But that is just what I beleive
maybe
the gurus have a differing opinion.
For 2, I believe that we are reqd. to keep 2 sets of stats one for the
swapped label and one for the pushed label
	Thanx,
Vip
vsharma@ieee.org

Attached message
=================================================================


>         In the MPLS MIBs (MPLS TE , MPLS LSR MIBs)I see stats for
errored
> packets.
>For e.g. in the MPLS LSR MIB there is mplsInSegmentErrors which is "The
>number of errored packets received on this segment."
>         My question is what type of errors make these packets errored
packets
>because most errored packets are dropped at the physical interface
iteself
>by the chips (my understanding). So does this stats put a req. to run
the
>phy. interface device in promiscous mode?

         Basically any case where a labeled packet is received and
cannot be forwarded by the MPLS software. There are many cases:
out of bandwidth in the switching fabric, illegal labels in the
packet, etc...


         --Tom




>Vip
>

-----Original Message-----
From: owner-mpls@UU.NET [mailto:owner-mpls@UU.NET]On Behalf Of S. Davari
Sent: Monday, June 11, 2001 6:42 PM
To: mpls@UU.NET
Subject: LSR-MIB Question


Hi All,

A few questions regarding LSR-MIB:

1) If TTL expires in an MPLS packet is the packet
counted in
mplsInSegmentErrors" or not?

2) If we receive a labeled packet and swap the label
and then push a new label
do we keep 2 sets of statistics on the outgoing
segment, one for the swapped
label and one for the pushed label or only one?

BTW, I also noticed that in LSR-MIB a swap consists of
a pop on incoming segment followed
by a push on outgoing segment, this is odd !! The
odder thing is that the incoming segment has
a parameter called InSegmentNpop in which "N"
identifies the number of pops to be performed on the
insegment. How does one know in advance how many pops
to perform? If you know that, then it means
that all those labels that you pop are not used at
all.

Thanks,
-Shahram

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