PORT ID on 7750 for snmp request

[avivi]

hi
how i calculate the PORT ID of port in 7750 , for example :
port 1/2/5 on 7750 , what is the PORT ID ?
i need that for snmp request .

[TroyM]

Physical Ports and LAGs follow a predictable IfIndex calculation. Virtual ports (i.e. SAPs, SDPs, VPRN interfaces, IP Interfaces, etc) do not follow a predictable ifIndex (hence the need for persistence files).

I've included both Physical port and LAG calculations below. In both cases the iFindex is a 32bit integer. The bits of the IfIndex are broken down in the following format (with Bit 31 being MSB and Bit 0 being LSB):

Binary Number: AAABBBBCCCCDDDDDDEEEEEEEEEEEEEEE

• A: Bits 31-29 (3 Bits)
  B: Bits 28-25 (4 Bits)
  C: Bits 24-21 (4 bits)
  D: Bits 20-15 (6 bits)
  E: Bits 14-0 (15 bits)

Here is what I have figured out for Physical ports:

• A => 000 (0 decimal)
  B => Slot Number (i.e. 0001 for slot 1, 0010 for slot 2, 0011 for slot 3, 1010 for Slot 10)
  C => MDA Number (i.e. 0001 for MDA 1, 0010 for MDA 2)
  D => Port Number on MDA (i.e. 000001 for Port 1, 000011 for Port 3, 001111 for port 15)
  E => All Zeros (000000000000000, 15 zeros)

For the CPM cards, the above can be used, but the MDA (C) value is always 0, Port is always (1), and the slot number depends on if ESS/SR-7 or ESS/SR-12. For ESS/SR-7 Control Card A is slot 6 and Card B is slow 7, for ESS/SR-12 the Control Card A is slot 11 and Control Card B is slot 12.

And for LAGs:

• A => 010 (2 in decimal)
  B => 1000 (8 in decimal)
  C => 0000 (0 in decimal)
  D => 000000 (0 in decimal)
  E => Lag Number (i.e. 000000000000001 for LAG-1, 000000000000011 for LAG-3, 010100000000000 for LAG-200
  etc)

-T

[rekeds]

why not snmp walk ifDescr/ifName/ifAlias to get the indexes?

admin display config indexes..