Good evening,
I try to figure out which VLANs are allowed on a Cisco Switch port configured as Trunk.
I read via SNMP the Cisco_VTP_MIB which returns me this information in the form :
Index : blabla, blabla beeing a 1024 bits field.
Example (obtained with a MIB browser)
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 10 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
16 Bytes/ Line x 8 Lines = 128 Bytes x 8 bits or Vlans = 1024 Vlans
16 Bytes / Line => 1st line covers Vlan Indexes from 0 to 127
the O2 is 134th bit =>Vlan 134,
the 10 is 810th bit => Vlan 827
The port in question is condigured as
switchport trunk allowed vlan 134,827
I was hoping that a loop with the shift left (<<) would allow me to find out which bit are set to one (like in assembler, but there is no "Carry" bit in which the shifted out bit can go).
Any idea out to find out the ones - and where they are - in a 1024 bits long binary-field.
Thanks
Juju

In reply to Working with BIG binary fields by juju

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