Visara CNA-8000 Installation - Manual (Page 79)

CNA-8000 Installation and Configuration
707158-003 6-5
Bit-Swapping LAN Addresses
Whenever you have a cross media LAN circuit connection between Ethernet and Token
Ring, you will probably need to bit-swap the LAN addresses to complete your
configuration. This is because of the way the address is identified between the two media.
The low order bit designation is opposite between the two LAN media. That is, the most
significant bit in one media is the least significant bit in the other media. This only
becomes an issue when you are entering the LAN addresses that you need as part of the
configuration.
The address that you enter for your media is always correct for your media, but if you are
referencing the address of another platform that is attached to the other media, then you
must reference the bit swapped version of that address. (For example the CNA-8000 is
attached to a Token Ring and the DSPU is attached through an LLC bridge on Ethernet.)
Following you will find an example of a procedure you can use to bit swap an address.
For the example, we will bit-swap the Token Ring address 40:00:37:45:00:16 to the
equivalent that would be seen on an Ethernet drop.
Bit swapping is performed on a byte by byte basis. Separating the address into individual
bytes, we end up with:
40
00 37 45 00 16
which translates to the binary representation of:
01000000 00000000 00110111 01000101 00000000 00010110
Now if we swap the bits of each byte we will have:
00000010 00000000 11101100 10100010 00000000 01101000
Now displaying the resulting hex values again we have:
02
00 EC A2 00 68
And bringing it back together :
02:00:EC:A2:00:68
So the bit-swapped version of 40:00:37:45:00:16 is 02:00:EC:A2:00:68.