June Backbone Engineering Report

Ittai Hershman ittai at ans.net
Wed Jul 15 22:23:22 UTC 1992

In response to your message, I thought it might be helpful to
summarize the status of SNMP variable support for the various adapter
technologies used in the RS/6000 based routers.

The RS960 T3 (HSSI) adapter uses HDLC framing point-to-point.  The
destination MAC address on these links always begins with 0xFF03: 0xFF
says that this is a "broadcast" packet, which means that I either want
it to go to whomever is at the far end, or that I am taking advantage
of the multidrop features in HDLC and I want everyone to get this
(BTW, 03 says that this is a data packet).  Strict interpretation of
MIB-II directs that if the MAC address was broadcast, then the packet
should be counted as non-unicast.  And this is reflected in the IBM
SNMP support for these adapters.

For T960 cards, however, we count Unicast packets, since we are
addressing a single station (they do not use HDLC framing).

The following matrix provides a summary of SNMP support for each of
the adapter types used in the RS/6000 based routers:

		  inU  outU  inNU  outNU  inOct outOct InErr OutErr
T960 T1		| IN   OUT    0      0     0      0    IN+OUT  0   |
T960 Ethernet	| U+B  U+B    0      0     0      0    IN+OUT  0   |
RS960 (all)	|  0    0     IN    OUT	   OK     OK     OK    OK  |

I do not have the matrix information for the current FDDI "Hawthorne"
technolgy cards.  But, they will soon be replaced by RS960 based FDDI
cards for which the subagent will behave just as that of the RS960 T3


Returning to the specifics of Jian Li's report, the questioned MIB-II
Interface counters are listed as follows:

             Ethernet:    ifIndex = 3
             ifInOctets = 0,                ifOutOctet = 0
             ifInUcastPkts = 816175323,     ifOutUcastPkts = 964648059
             ifInNUcastPkts = 0,            ifOutNUcastPkts = 0

Comment: This interface must be a T960 card, which does not collect ifInOctets
         and ifOutOctets.  The InUcastPkts and InNUcastPkts are collected in
         the counter ifInUcastPkts.  The OutUcastPkts and OutNUcastPkts are
         collected in the counter ifOutUcastPkts.

             T3:           ifIndex = 4
             ifInOctets = 1532701256,       ifOutOctets = 2614141685
             ifInUcastPkts = 0,             ifOutUcastPkts = 0
             ifInNUcastPkts = 1033010978,   ifOutNUcastPkts = 897328785

Comment: The packets are counted as NUcastPkts.


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