Program Code

Special Program

 

 

1

Network Management dispatching program

 

 

3

Orphan/Bad Packet handling routine

 

(normally HP Node Manager software)

 

 

5

Transmit Trace Packet handling routine

 

(normally HP Node Manager software)

 

 

7

Group DSAP Packet handling routine

 

 

9

VCP Server program

 

 

11

Ethernet Packet handling routine

 

 

The range for Ethernet types is 05DD " FFFF hex.

A new entry is created in the driver's class table when a request is made to post a class number for a new SAP, PC, or ET. If a new class number is posted to an existing SAP, PC, or ET, the previous class number is overwritten. However, note that a program may post its class number to more than one SAP, PC, or ET.

Under normal circumstances (see the •Node Manager Software Initialization" section later in this chapter), Node Manager software will post its class number for receiving packets to SAP F8 hexadecimal (248 decimal), and to Program Code 3 (•bad" and •orphan" packet handling routine) and Program Code 5 (transmit •trace" packet handling routine).

Packet Routing

When the LANIC card receives a packet, the driver is scheduled. Among information the driver obtains from the packet is its Destination Service Access Point (DSAP). (See Chapter 2 for the DSAP location within a packet.)

If the packet's DSAP is F8 hex, the driver searches the class table and retrieves the class number associated with SAP F8 hex (normally the Node Manager software class number for receiving packets). The driver then transfers the packet to System Available Memory (SAM) and queues it on the Node Manager's class number. The Node Manager software retrieves the packet from SAM through a pending Class Get request, and processes the packet data accordingly.

If a bad packet is received and the card is configured to save •bad" packets, the driver will enter the class table and retrieve the class number associated to Program Code 3. The packet will be passed to the program that posted its class number to PC 3 (normally, the Node Manager software).

Suppose an incoming packet contains a DSAP for which there is no class number, or the class number is invalid. If the LANIC card driver is configured to save •orphan" packets, the packet will be passed to the program that posted its class number to Program Code 3 (normally, the Node Manager software).

A transmit •trace" packet is a packet returned to the driver when it fails to transmit due to an error (the LANIC card must be configured to return trace packets). These packets are queued on the class number associated with Program Code 5. The packet will be retrieved from SAM by a trace packet handling program who posted its class number to Program Code 5 (normally, Node Manager software).

Node Manager Operations 4%9