AIS Router AI2524 - Manual (Page 294)

AI2524 Router Card User’s Manual
Page 12-36 August 1997
2524UM
Flow control is maintained end-to-end. This was previously called re-
mote switching or tunneling.
Running X.25 over TCP/IP provides a number of benefits. Other rout-
ers can switch IP datagrams containing the X.25 packets using the
router's high-speed switching abilities. X.25 data can be sent over net-
works running only TCP/IP protocols. The TCP/IP protocol suite runs
over many different networking technologies, including Ethernet,
Token Ring, T1 serial, and FDDI. Thus X.25 data can be forwarded
over these media to another XOT host where it can be output to an
X.25 interface. Both interfaces must define complementary tunneled
PVCs.
To configure a remote PVC to connect across a TCP/IP LAN, type (in
interface configuration mode):
x25 pvc number1 tunnel address interface
serial string pvc number2 [ option ]
The command options ar packetsize in out and window-
size in out ; they allow a PVC's flow control values to be defined
if they differ from the interface defaults.
Each XOT connection relies on a TCP session to carry traffic. If you
do not enable TCP keepalives, XOT PVCs might encounter problems
if one end of the connection is reloaded. When the reloaded host at-
tempts to establish a new connection, the other host refuses the new
connection because it has not been informed that the old session is no
longer active. Recovery from this state requires the other host to be in-
formed that its TCP session is no longer viable so that it attempts to
reconnect the PVC.
Example: Remote PVC Tunneling
In the more complex example shown in Figure 12-5 , the connection
between points A and B is switched, and the connections between