RFC 2173 (rfc2173) - Page 3 of 6
A MAPOS version 1 Extension - Node Switch Protocol
Alternative Format: Original Text Document
RFC 2173 MAPOS June 1997
the node address is 0 + 01 + 00011, that is, 00100011(0x23). Node N3
has an address 01001001(0x49), since the switch number of S2 is 0x2
(10 in binary) and the port number is 0x09. Note that all the port
numbers are odd because the LSBs are always 1.
+------+
| node |
| N1 |
+------+
| 00100011(0x23)
|
|0x3 |0x3
+------+ +---+----+ +---+----+ +------+
| node +----+ SONET +-------+ SONET +-----+ node |
| N2 | 0x5| Switch |0x9 0x5| Switch |0x9 | N3 |
+------+ | S1 | | S2 | +------+
00100101(0x25) | 0x1 | | 0x2 | 01001001(0x49)
+---+----+ +---+----+
|0x7 |0x7
Figure 2 Addressing in Multiple Switch Environment
4 NSP(Node-Switch Protocol)
This section describes the NSP protocol used for automatic node
address assignment.
4.1 NSP protocol
NSP is introduced to provide an automatic node address assignment
function in MAPOS version 1. It reduces the administrative overhead
of node address configuration for each node and prevents troubles
such as address inconsistency and collision. When a node is connected
to a switch and receives SONET signal correctly, the node sends an
address request packet to the control processor in the local switch.
The destination address of this packet is 00000001(0x01). When the
control processor receives the packet, it replies with an address
assignment packet. The destination is the assigned node address. If
the node does not receive the address assignment packet within 5
seconds, it retransmits the address request packet. The
retransmission continues until the node successfully receives the
address assignment packet.
Whenever a node detects a transmission error such as carrier loss or
out-of-synchronization, it SHOULD send an address request packet to
the control processor and verify its current address. In addition, a
node MUST verify its address by sending address request packets every
Murakami & Maruyama Informational