Perle Systems IOLINK-PRO IOLINK-520 - Manual (Page 29)

ISDN Connection Management
2.8 — IOLINK-PRO & 520 Reference Manual
IPX Specifics
RIP/IPX and SAP/IPX
IOLINK ISDN routers incorporate a 3 second settling time for IPX RIP and SAP updates. This means that an
IOLINK will wait for three seconds after an initial change in the network is reported before transmitting that
change on to the remaining IOLINK routers connected on the Wide Area Network.
Suspension of IPX Sessions
When Connection Management is enabled, IPX sessions that are established across the ISDN calls are
monitored and maintained in a table. The IPX connection table may contain up to 256 entries. The IOLINK
will filter all watchdog traffic for any IPX session over the 256 limit of the table preventing any new IPX
sessions from being established.
Server IPX Watchdog Frames
When the IOLINK router on the server side of the IPX session receives an IPX watchdog packet from the
server on the local LAN, the IOLINK router will pass the watchdog packet to the remote partner IOLINK
router and then to the client side of the IPX session. Once the client side of the session has responded to the
IPX watchdog, the IOLINK router on the server side of the IPX session will consider all future IPX
watchdog packets for this session to be non-interesting and will not pass them across the ISDN call.
The IOLINK router on the server side of the IPX session will generate a response to each IPX watchdog
packet sent by the server and send the response back to the server on the local LAN. In this way, the local
IOLINK router will keep the ISDN call suspended and will also keep the local side of the IPX session active.
While an ISDN call is suspended, if the IOLINK router on the server side of the IPX session observes that
the server has stopped generating IPX watchdog packets, the IOLINK router will assume that the server has
gone away and alert the IOLINK router on the client side of the IPX session. The IOLINK router on the
client side of the IPX session will stop generating IPX watchdog packets for that IPX session.
Client IPX Watchdog Frames
When the IOLINK router on the client side of the IPX session observes an IPX watchdog packet from the
server side of the IPX session sent to the client, and later an IPX watchdog reply being sent from the client
back to the server, the IOLINK router on the client side of the IPX session will begin to generate and send
IPX watchdog packets to the client on behalf of the server.
While an ISDN call is suspended, if the IOLINK router on the client side of the IPX session observes that
the client has stopped responding to the IPX watchdog packets, the IOLINK router will assume that the
client has gone away and will alert the IOLINK router on the server side of the IPX session. The IOLINK
router on the server side of the IPX session will stop responding to the IPX watchdog packets for that IPX
session and will filter all remaining IPX watchdog packets generated by the server until the server has
determined that the client has gone away.
The time interval between the IPX watchdog packets generated by the IOLINK router on the client side of
the IPX session may be defined by the operator by setting the Watchdog Interval option in the IPX Routing
Set-Up menu.
IPX Serialization Frames
The IOLINK router will prevent IPX serialization frames from activating a suspended ISDN call by filtering the
IPX serialization frames. The IOLINK router will allow IPX serialization frames to be passed to the WAN
when the ISDN call is active.