User`s guide

System Initialization and Acceptance Testing (Normal Operation)
4.7 Operating System Bootstrap
Table 4–4 (Cont.) Supported MOP Messages
Message Type Message Fields
LOOPBACK
LOOP_DATA Skpcnt
nn-nn
Skipped bytes
bb-...
Function
00-02 Forward
data
Forward
addr
ee-ee-
ee-ee-
ee-ee
Data
dd-...
LOOPED_DATA Skpcnt
nn-nn
Skipped bytes
bb-...
Function
00-01 Reply
Recpt #
nn-nn
Data
dd-...
IEEE 802.2
XID_CMD/RSP Form
81
Class
01
Rx window size (K)
00
TEST_CMD/RSP Optional data
VMB, the requester, starts by sending a REQ_PROGRAM message to the
MOP ’dump/load’ multicast address. It then waits for a response in the form
of a VOLUNTEER message from another node on the network, the MOP
server. If a response is received, then the destination address is changed from
the multicast address to the node address of the server and the same REQ_
PROGRAM message is retransmitted to the server as an Acknowledge.
Next, VMB begins sending REQ_MEM_LOAD messages to the server. The
server responds with either:
• MEM_LOAD message, while there is still more to load.
• MEM_LOAD_w_XFER, if it is the end of the image.
• PARAM_LOAD_w_XFER, if it is the end of the image and operating system
parameters are required.
The "load number" field in the load messages is used to synchronize the
load sequence. At the beginning of the exchange, both the requester and
server initialize the load number. The requester only increments the load
number if a load packet has been successfully received and loaded. This forms
the Acknowledge to each exchange. The server will resend a packet with a
specific load number, until it sees the load number incremented. The final
Acknowledge is sent by the requester and has a load number equivalent to the
load number of the appropriate LOAD_w_XFER message + 1.
4–32 System Initialization and Acceptance Testing (Normal Operation)