RFC 2174 (rfc2174) - Page 3 of 22
A MAPOS version 1 Extension - Switch-Switch Protocol
Alternative Format: Original Text Document
RFC 2174 MAPOS June 1997
3.1 Address Structure of MAPOS version 1
In a multiple switch environment, a node address consists of the
switch number and the port number to which the node is connected. As
shown in Figure 1, the address length is 8 bits and the LSB is always
1, which indicates the end of the address field. A MSB of 0 indicates
a unicast address. The switch and the port number fields are
variable-length. In this document, a unicast address is represented
as "0 ". Note that a port number
includes EA bit.
MSB of 1 indicates multicast or broadcast. In the case of broadcast,
the address field contains all 1s (0xff in hex). In the case of
multicast, the remaining bits indicate a group address. The switch
number field is variable-length. A multicast address is represented
as "1 ".
Switch Number(variable length)
|
| +--- Port Number
| |
V V
|||
+-------------+-+
| | | | | | | | |
| | |1|
+-+-----------+-+
^ ^
| |
| +------- EA bit (always 1)
|
1 : broadcast, multicast
0 : unicast
Figure 1 Address Format
Figure 2 shows an example of a SONET LAN that consists of three
switches. In this configuration, two bits of a node address are used
to indicate the switch number. Node N1 is connected to port
0x03(000011 in binary) of the switch S2 numbered 0x2. Thus, the node
address is 01000011 in binary. Node N4 has an address 01101001 in
binary since the connected switch number is 0x3 and the port number
is 0x09.
Murakami & Maruyama Informational