Motorola 110502USM001 - Vanguard 60 Router User Manual page 21

Flow Control
Call Disconnection The Vanguard Router uses the X.25 mode for establishing virtual circuits over the
Statistics
Summary Status
Vanguard Routing Model
T0100-01, Revision B
Data passed from the LAN protocol stacks to the WAN Adapter may be queued
inside the WAN module. This is due to the relatively low bandwidth of the WAN
port(s) compared with a LAN port and to competition for that limited WAN port
bandwidth with serial data access ports. When this occurs, data flow between the
WAN Adapter and the WAN protocol stack is temporarily halted to allow the WAN
port to reduce its queues to a manageable level. Detection of this condition and
reaction to it is referred to as flow control. Data waiting for transmission onto a WAN
link is kept on an LCON queue. The maximum size of this queue is configurable.
However, data passed from the WAN Adapter to the LAN protocol stacks should be
transmitted almost immediately due to the significantly higher bandwidth of the
LAN port compared to the WAN port(s).
WAN. Connections to remote destinations can be disconnected at any time due to
network failures and operator interventions.
• The WAN Adapter recognizes when it receives a Clear Indication packet that
a call is disconnected and notifies the LAN forwarders.
• The WAN Adapter flushes its flow control queues of any saved packets.
• If the LAN Connection has an Autocall Mnemonic configured, the WAN
Adapter restarts the call establishment process.
• If the LAN connection is not configured to autocall, no call establishment
actions occur until receipt of an Incoming Call packet from the remote
destination.
The WAN Adapter maintains, displays, and resets its statistics independently of the
WAN protocol stack and the LAN protocol stacks. All interaction is through the
standard CTP interface.These statistics are shown in the LAN Connection Statistics
screens.
The WAN Adapter provides an LCON Summary Status display that contains
information about all configured LAN connections, their associated bridge-links, and
their associated router interfaces.
WAN Adapter
2-5
Release 5.4