Visara FEP-4600 Installation - Manual (Page 58)

Chapter 5. Token Ring Interface
5-6 707119-001
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 FEP-4600 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) subchannel address in the FEP-4600 configuration (see chapter on
Static Gateway Circuits).
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 FEP-4600 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 by the FEP-4600 for an SNA XID. The XID
response from the downstream platform will be matched to a configured upstream
(ESCON) subchannel address that is configured for that specific XID (IDBLK + IDNUM
options). If a match is found, 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. A maximum of 16 dynamic circuits per interface will be
permitted.
SAP Assignments
The same Local SAP number can be used for multiple drops and will automatically
default to a value of ‘04’ on the FEP-4600. SAPs used for SNA communication must be a
multiple of ‘04’ hex (04, 08, 0C, 10, 14, etc.), and must be between the values of 04-EC.
If more than one PU connection is to be made between the FEP-4600 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 FEP-4600, when defining Dynamic Connections or XCA drops,
use a different SAP for each of those that is not duplicated by the static PU2 connections
or PU4 connections.