Down-Line Loading the Customized DECrouter 200 Software Image
5.2 The Different Ways to Initiate a Down-Line Load
You can initiate a down-line load in these ways:
• Power on the DECrouter 200 unit by plugging in the power plug.
• Issue the NCP LOAD command from a load host.
• Issue the NCP TRIGGER command from any supported management host.
Each way works somewhat differently. The best method to use depends on your loca-tion and whether you want to ensure that a particular load host loads the router.
5.2.1 How Power Up Works
If you are at the DECrouter 200 unit, plugging in the power cord is a convenient way to load the router. The initialization process starts immediately.
Plugging in the power cord has one advantage. Since you are at the DECrouter 200 unit, you can observe the LED display. Several codes show the status of the loading process. The LEDs are helpful for troubleshooting. See Section 8.1 for the meaning of each code.
The power-up method to initiate a down-line load instructs the router to multicast a MOP REQUEST PROGRAM message to all DEC net nodes on the router's Ethernet.
This message requests a down-line load from any assigned load host.
This method does not ensure that a particular load host performs the down-line load, if there is more than one load host, as Digital recommends. With this method, you do not know beforehand which load host will actually down-line load the router's software image.
5.2.2 How NCP LOAD Works
You must issue the NCP LOAD command at a load host. The advantage of the NCP LOAD command is that it ensures that the load host at which you issue the command is the node that performs the down-line load. Note that the down-line load, however, may be slower than with the TRIGGER command.
You can specify parameters on the NCP LOAD NODE command line to override cur-rent parameter values in the load host's node database.
Down-Line Loading the Customized DECrouter 200 Software Image 5-3
When you issue the LOAD command, the load host must have service enabled on its Ethernet circuit or it cannot perform a down-line load. The ROUCONFIG procedure automatically enables service but it may have been disabled some time after the router software installer ran ROUCONFIG. To enable service, issue this NCP command:
SET CIRCUIT circuit-id SERVICE ENABLED
where circuit-id identifies the Ethernet circuit for the host.
This is how the LOAD command works:
1. You issue the LOAD command on one of your router's load hosts.
2. The load host sends a MOP REMOTE CONSOLE BOOT message with a direct load option specified.
3. When the router receives this message, the router sends a MOP REQUEST PROGRAM message directly to that load host.
4. The load host and the router use additional MOP messages to transfer the router's software image, one block at a time, into the router's memory.
Figure 5-1 shows a router manager on load host HOST 1 issuing LOAD to load router JUNIOR, over service circuit UNA-O. Figure 5-2 shows JUNIOR asking HOST1 for a down-line load. Figure 5-3 shows HOST1 down-line loading JUNIOR's software image to JUNIOR. The arrows show the message path that LOAD generates.
NCP>LOAD NODE JUNIOR
HOST1 HOST2 HOST3
UNA-O
CONSOLE
EVENT MESSAGES AT CONSOLE PRINTER
LKG-2513-88
Figure 5-1: Router Manager Enters LOAD Command at HOST1
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HOST1 HOST2 HOST3
UNA-O
LKG-2518-88
Figure 5-2: Router JUNIOR Asks HOST1 for a Down-Line Load
CONSOLE HOST1 HOST2 HOST3
EVENT MESSAGES AT CONSOLE PRINTER
UNA-O
Figure 5-3: HOST1 Loads Router JUNIOR
Down-Line Loading the Customized DECrouter 200 Software Image
LKG-2514-88
5-5
5.2.3 How NCP TRIGGER Works
The advantage of using the NCP TRIGGER command is that you do not have to be on a load host. You can issue NCP TRIGGER from any of the router's supported man-agement hosts. The TRIGGER command has the same effect as loading the software by an electrical power-up at the hardware unit.
In addition, depending on the load host, the down-line load is likely to be faster than with the LOAD command. TRIGGER is usually faster than LOAD because the router does not have to wait for a particular load host to respond to its request.
The TRIGGER command does not ensure that a particular load host performs the down-line load. With this method, you do not know beforehand which load host will actu-ally down-line load the router image. An event message informs you after the load.
You can specify parameters on the NCP TRIGGER NODE command line to override current parameter values in the load host's node database.
When you issue the TRIGGER command, potential load hosts must have service ena-bled on their Ethernet circuits or they cannot perform a down-line load. The ROUCONFIG procedure automatically enables service, but it may have been disabled some time after the router software installer ran ROUCONFIG. To enable service, issue this NCP command:
SET CIRCUIT circuit-id SERVICE ENABLED
where circuit-id identifies the Ethernet circuit for the host.
This is how the TRIGGER command works:
1. You issue the TRIGGER command on one of the network's management hosts.
This system may also be one of your router's load hosts but it is not required.
2. The management host sends a MOP REMOTE CONSOLE BOOT message with the TRIGGER option specified.
3. When the router receives this message, the router multicasts a MOP REQUEST PROGRAM message.
4. The first load host that responds and the router both use additional MOP mes-sages to transfer the router's software image, one block at a time, into the router's memory. The router ignores other responders once the load is in progress.
Figure 5-4 shows a router manager on a management host issuing TRIGGER to load router JUNIOR. (Note that this management host is not also a load host, which is a possible condition.) Figure 5-5 shows JUNIOR multicasting a request for a down-line load. Figure 5-6 shows one of JUNIOR's load hosts responding by down-line loading the software image to JUNIOR. The arrows show the message path that LOAD generates.
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NCP>TRIGGER NODE JUNIOR