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Re: (ASCEND) Request for comments: Proposed changes to the SNMP Interface MIB support

At 21:05 1998/04/23 -0400, ken wrote:
>We have completed a draft of the changes that we plan on making to the MAX
>and TNT MIBII interface table.

>Problem:
>    - Interface statistic counters are incremented only for the session
>    layer interface entries - WAN ports; these interfaces move around.
>
>Solution:
>- All nailed interfaces will have counters at the link level - PPP or Frame.
>Octet counters will not be supported for switched DS1 interfaces. Tracking
>the octets on PRIs used for switched calls isn't very useful. On these
>interfaces Measuring channel usage is.

While I will agree that measuring the individual users is not very interesting,
measuring the octet counts on switched WAN links is very useful
when you use the links the way that I do, for permanent/switched links
or dial-on-demand networks. (I have NO nailed or leased links on my Maxen)
We (and many others) have worked around this before by scanning 
the entire interface tree and parsing out the IP address of the links 
we need, and then pulling the counts from there. (yes it is SLOW!)

>Problem
>    - WAN entries for nailed connection in the interface table
>    move around.  This makes it very difficult for Network Management
>    Station to poll for historical data.
>
>Solution
>    The value of ifIndex of an interface entry in the interface table will
>    be saved in NVRAM or Flash so it will not change between system reboot.
>    Also if an entry is dynamically removed from the interface table, its
>    ifIndex value must not re-used until after the following
>    re-intialization of the network management agent.

If you are going to remove our ability to scan the entire tree
(because the WAN interfaces will no longer be listed there)
then you must give us the option to manually associate
an interface number with a particular connection profile,
(with appropriate error checking that an index is not already in use)
and it could even be the same method used to associate the
interface number of nailed connections, something like:

  ethernet->Connections->MyWANLinkName->Encaps options->ifIndex=101

this way the system doesn't have to keep track of the interface index
in some hidden area of NVRAM, and gives the user complete control
over how they want to track link usage.

One additional idea, since it sounds like this is going
to be a major overhaul anyway, would be to make
        physical interface numbers <100
                ethernet, Sync Serial, DS3/1/0, etc.,
        configured connection profile numbers >=100 & <1000
                named connections, locally configured with ifIndex#
                maybe profiles from Radius too if feasible
        dynamic WAN interface numbers >1000
                exactly the way WAN interface are now, 
                down to the DS0, just renumbered...
then if someone REALLY needs to parse the entire tree
for dynamic WAN stats they still can, (backward compatibility?)
and might allow an agent to get a full list of interfaces,
and then "walk the tree" for only indices 100 through 999.

-Jim H
----
Jim Howard             Sr Network Engineer        Lyceum Internet
jhoward@lyceum.com     http://www.lyceum.com/     404.248.1733     

My PGP Public Key: http://www.lyceum.com/~jhoward/pgp-key.txt
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