ISDN Connection Management
18
Combination
A combination of the Address Connect and A uto-Call options may be configure d when a semi-permanent connection
is required to one remote site and a dynamic connecti on is required to multiple sites. A dy namic 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 .
555-1000
555-8000
The ISDN connection i s made
using the
to the ap propriate remote network
according t o t he ent ri e s i n th e
Address Connect table.
secondB-channel
This ISDN connect i on i s made
using the
upon initial po wer-u p and i s
maintained ac cor di ng t o t he
Auto-Call pa rameters.
firstB-channel
Network B
Network X
Network H
Network A
555-2000
ISDN N etwo rk
Remote Networ k
Network B
Network C
Network D
Network E
Network F
Network G
Network H
555-2000
555-3000
555-4000
555-5000
555-6000
555-7000
555-8000
ISDN Numbe r
Networks C t hr o ugh G
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 l ocated on a remote LAN, the session connection request mus t be sent to that remote
LAN before the server can process the session connection request and reply to it. Any of the call establi shment processes
may be used to establish the ISDN call between the P840s 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 pack ets are used to verify the statu s of the device at the opposite end of the session.
When Connection Management is enabled, LAN s essions 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 P840
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 P840.
While an ISDN call is up and connected, all traffic within the sessions will be transferred to the partner P840 across the
ISDN call.