Visara CNA-8000 Installation - Manual (Page 68)

Chapter 5. Token Ring Gateway
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Drop Panel Option Determination
Below you will find a discussion on how to determine values for some of the options
found on the Token Ring Drop Panels.
Static vs Dynamic Drops
Token Ring Drops on the CNA-8000 can be set up two different ways.
 Static
 Dynamic
Static Drops:
Static drops offer simplicity and security. Defining a static drop means that you will
configure the MAC address and SAP of the downstream platform. Only that platform can
connect to this circuit. The Token Ring end of the circuit must be configured to a specific
upstream (ESCON) XCA portal.
Dynamic Drops:
Dynamic drops offer flexibility and may be used as part of a disaster recovery scenario.
Defining a dynamic drop means that any downstream platform configured to seek out the
MAC address of the CNA-8000 interface, and connecting to the Local SAP associated
with this drop definition, will be allowed to attempt to make a connection. The
downstream platform will be challenged for an SNA XID. The XID response from the
downstream platform will be forwarded through the XCA gateway up to VTAM to be
matched to a configured VTAM switched PU2 definition for that specific XID (IDBLK +
IDNUM options). If a match is found by VTAM, the upstream to downstream circuit will
be generated dynamically (for the length of the session). If no match is found, the
downstream platform will be disconnected.
SAP Assignments
The same Local SAP number can be used for multiple drops and will automatically
default to a value of ‘04’ on the CNA-8000. SAPs used for SNA communication must be
a multiple of ‘04’ hex (04, 08, 0C, 10, 14, etc.) for use on Z/OS systems or a multiple of
‘02’ hex (04, 06, 08, 0A, 0C, 0E, 10, etc) for use on Z/VM systems, and must be between
the values of 04-EC. If more than one PU connection is to be made between the CNA-
8000 and the same platform (same LAN address), a unique combination of Remote SAP
address and Local SAP address must be used for each circuit (drop). For example a
combination of RSAP = 04, LSAP=04 and RSAP=08, LSAP=04 would be a valid
configuration for a downstream platform that requires two PUs to be defined. SAP
numbers are assigned on both platforms conducting the PU session, and typically must be
configured to communicate with each other. On the CNA-8000, when defining Dynamic
Connections or XCA drops, use a different SAP for each of those that are not duplicated
by the static PU2 connections.