ISDN Connection Management

Combination

A combination of the Address Connect and Auto-Call options may be configured when a semi-permanent connection is required to one remote site and a dynamic connection is required to multiple sites. A dynamic connection indicates that the remote site for the second ISDN call will change depending upon what destination IP address is required for the connection. One ISDN B-channel is configured to have an Auto-Call ISDN number and the other B-channel may be used for the Address Connect functions.

Network X

This ISDN connection is made using the first B-channelupon initial power-up and is maintained according to the Auto-Call parameters.

Network A

555-1000

The ISDN connection is made using the secondB-channel

to the appropriate remote network according to the entries in the

Address Connect table.

Remote Network ISDN Number

Network B

555-2000

Network C

555-3000

Network D

555-4000

Network E

555-5000

Network F

555-6000

Network G

555-7000

Network H

555-8000

555-2000

ISDN Network

555-8000

Network B

Networks C through G

Network H

Figure 2 - 3 Auto-Call & Address Connect WAN Topology

Connection Process

When a LAN client requests a session with a LAN server, the client will initiate the session by sending a session connection request to the server. If the server is located on a remote LAN, the session connection request must be sent to that remote LAN before the server can process the session connection request and reply to it. Any of the call establishment processes may be used to establish the ISDN call between the IOLINK routers in order to establish a LAN session between the local and remote LANs.

Once the client-server session has been established, keepalive or status packets are generated by either or both ends of the session. The keepalive packets are used to verify the status of the device at the opposite end of the session.

When Connection Management is enabled, LAN sessions that are established across the ISDN calls are monitored and maintained in a table. The session table may contain up to 256 entries for each supported session type, with the IOLINK router filtering all traffic for any sessions over the 256 limit of the table. The 257th and greater LAN sessions will not be allowed by the IOLINK router.

While an ISDN call is up and connected, all traffic within the sessions will be transferred to the partner IOLINK router across the ISDN call.

2.4IOLINK-PRO & 520 Reference Manual

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Perle Systems IOLINK-520 manual Connection Process, Combination