ISDN Connection Management
2-8 — Orbitor 3000 Reference Manual
IPX Specifics
RIP/IPX and SAP/IPX
Orbitor ISDN routers incorporate a 3 second settling time for IPX RIP and SAP updates. This means that an
Orbitor will wait for three seconds after an initial change in the network is reported before transmitting that
change on to the remaining Orbitor 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 Orbitor
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 Orbitor on the server side of the IPX session receives an IPX watchdog packet from the server
on the local LAN, the Orbitor will pass the watchdog packet to the remote partner Orbitor and then to the
client side of the IPX session. Once the client side of the session has responded to the IPX watchdog, the
Orbitor 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 Orbitor 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
Orbitor 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 Orbitor on the server side of the IPX session observes that the
server has stopped generating IPX watchdog packets, the Orbitor will assume that the server has gone
away and alert the Orbitor on the client side of the IPX session. The Orbitor on the client side of the IPX
session will stop generating IPX watchdog packets for that IPX session.
Client IPX Watchdog Frames
When the Orbitor 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 Orbitor 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 Orbitor on the client side of the IPX session observes that the
client has stopped responding to the IPX watchdog packets, the Orbitor will assume that the client has
gone away and will alert the Orbitor on the server side of the IPX session. The Orbitor 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 Orbitor 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 Orbitor will prevent IPX serialization frames from activating a suspended ISDN call by filtering the
IPX serialization frames. The Orbitor will allow IPX serialization frames to be passed to the WAN when the
ISDN call is active.
