APN Configuration and Management Manual

Configuring for Ethernet Support

SNAX/XF and SNAX/APN Configuration and Management Manual—425836-006

10-15

Link-station Role Negotiation

SNAX allows you to specify STATION NEGOTIABLE on lines connected to an Ethernet

network. Role negotiation is implemented using SNA XID exchanges and SNAX

negotiates with the remote link-station to determine which station will assume the

primary role and which station will assume the secondary role.

Unique Addressing

An architected rule of SNA over LAN is that there may only be one connection between

any two SAPs because the SAP/MAC address identifies the link-station (see

Figure 10-7 on page 10-10). Figure 10-11 shows the effect this restriction has on the

relationship of PUs to SAP values.

In SNA terms, the link-station is the equivalent of a PU. Consider the addressing used

to create a connection between PU1 and PU3. The address of PU1 is its SAP/MAC

address, in this case 0440001111000,1 and the address of PU3 is 04400011110002.

There can only be one session uniquely defined by the address

04400011110001,04400011110002.

Other PUs using the same SAP/MAC address 04400011110001 that also need to be

attached to PUs in Station B must be connected through a different SAP. In this

Figure 10-11. SAP and PU Addressing

PU1

Station A Station B

SAP

MAC

400011110001

PU3

%H04

%H08

LU1 LU2 LU3

PU2

PU4

%H04

400011110002

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