3com 3031 Instruccion De Instalación
Configuring X.25 over TCP (XOT)
313
Perform the following configuration in X.25 interface view.
Configuring X.25 over
TCP (XOT)
TCP (XOT)
Introduction to XOT
Protocol
XOT (X.25 Over TCP) is a protocol that is used to carry X.25 packet over TCP to
implement the interconnection between two X.25 networks via IP network. The
actual application environment is shown in the following figure.
implement the interconnection between two X.25 networks via IP network. The
actual application environment is shown in the following figure.
Figure 70 Typical XOT application
At present, since IP network is used widely, it is necessary, in practice, to carry X.25
data and implement the interconnection between X.25 networks via IP network.
The traditional X.25 protocol belongs to layer 3 (network layer) of OSI 7-layer
model, and it can obtain the reliable data transmission link via LAPB protocol.
Since TCP has such mechanisms as error retransmission and window flow control
to ensure the reliability of the link, it can be used by X.25 protocol. XOT
establishes a TCP tunnel connection between X.25 networks at both ends, and
X.25 packet, as the data of application layer, is carried over TCP, i.e. TCP serves as
“link layer" of X25. RouterB, RouterC and IP network in the middle can be looked
upon as a big “X.25 switch”, and the data sent by RouterA is directly switched to
RouterD via this “switch”.
data and implement the interconnection between X.25 networks via IP network.
The traditional X.25 protocol belongs to layer 3 (network layer) of OSI 7-layer
model, and it can obtain the reliable data transmission link via LAPB protocol.
Since TCP has such mechanisms as error retransmission and window flow control
to ensure the reliability of the link, it can be used by X.25 protocol. XOT
establishes a TCP tunnel connection between X.25 networks at both ends, and
X.25 packet, as the data of application layer, is carried over TCP, i.e. TCP serves as
“link layer" of X25. RouterB, RouterC and IP network in the middle can be looked
upon as a big “X.25 switch”, and the data sent by RouterA is directly switched to
RouterD via this “switch”.
XOT characteristics in V2.00 conforms to the RFC1613 standard, which features as
follows:
follows:
■
Supporting SVC application. The routers at both ends can dynamically establish
an SVC by sending call packet, and this SVC will be automatically cleared when
no data is transmitted.
an SVC by sending call packet, and this SVC will be automatically cleared when
no data is transmitted.
■
Supporting PVC application. After being configured with a PVC, the routers at
both ends need not to establish call and directly enter data transmission status.
Moreover, this PVC will not be dynamically deleted when no data is
transmitted.
both ends need not to establish call and directly enter data transmission status.
Moreover, this PVC will not be dynamically deleted when no data is
transmitted.
■
Supporting Keepalive attribute of TCP. If Keepalive is not configured, TCP
connection will still not be cleared or cleared after a long time even if the
connection is interrupted. However, after Keepalive is configured, TCP will
timely detect the availability of the link. If TCP does not receive the response
from the peer for many times, it will initiatively clear its connection.
connection will still not be cleared or cleared after a long time even if the
connection is interrupted. However, after Keepalive is configured, TCP will
timely detect the availability of the link. If TCP does not receive the response
from the peer for many times, it will initiatively clear its connection.
Table 382 Display CUG configuration
Operation
Command
Display CUG configuration
display x25 cug
X.25
IP
X.25
Router A
Router B
Router C
Router D
X.25
IP
X.25
Router A
Router B
Router C
Router D