User`s guide

System Initialization and Acceptance Testing (Normal Operation)
4.7 Operating System Bootstrap
Because the request for load assistance is a MOP "must transact" operation,
the network bootstrap continues indefinitely until a volunteer is found.
The REQ_PROGRAM message is sent out in bursts of eight at four second
intervals, the first four in MOP Version four IEEE 802.3 format and the last
four in MOP Version 3 Ethernet format. The backoff period between bursts
doubles each cycle from an initial value of four seconds, to eight seconds,...
up to a maximum of five minutes. However, to reduce the likelihood of many
nodes posting requests in lock-step, a random "jitter" is applied to the backoff
period. The actual backoff time is computed as (.75+(.5*RND(x)))*BACKOFF,
where 0<=x<1.
4.7.3.4 Network "Listening"
While the CPU module is waiting for a load volunteer during bootstrap, it
"listens" on the network for other maintenance messages directed to the
node and periodically identifies itself at the end of each 8- to 12-minute
interval before a bootstrap retry. In particular, this "listener" supplements the
Maintenance Operation Protocol (MOP) functions of the VMB load requester
typically found in bootstrap firmware and supports.
• A remote console server that generates COUNTERS messages in response
to REQ_COUNTERS messages, unsolicited SYSTEM_ID messages every
8 to 12 minutes, and solicited SYSTEM_ID messages in response to
REQUEST_ID messages, as well as recognition of BOOT messages.
• A loopback server that responds to Ethernet loopback messages by echoing
the message to the requester.
• An IEEE 802.2 responder that replies to both XID and TEST messages.
During network bootstrap operation, the KA52/53/54 complies with the
requirements defined in the "NI Node Architecture Specification" for a
primitive node. The firmware listens only to MOP "Load/Dump", MOP
"Remote Console", Ethernet "Loopback Assistance", and IEEE 802.3 XID/TEST
messages (listed in Table 4–5) directed to the Ethernet physical address of the
node. All other Ethernet protocols are filtered by the network device driver.
The MOP functions and message types, which are supported by the KA52/53
/54, are summarized in Tables 4–3 and 4–5.
System Initialization and Acceptance Testing (Normal Operation) 4–33