3com 3031 Instruccion De Instalación
36
DLS
W
C
ONFIGURATION
DLSw Overview
Data Link Switching, DLSw for short, is developed by Advanced Peer-to-Peer
Networking (APPN) Implementers Workshop (AIW) to support SNA (System
Network Architecture) through TCP/IP. SNA is a network protocol introduced by
IBM in 1970s, which is totally corresponding to the OSI reference model. To realize
the trans-WAN transmission of SNA protocol, one of the solutions is the DLSw
technique.
Networking (APPN) Implementers Workshop (AIW) to support SNA (System
Network Architecture) through TCP/IP. SNA is a network protocol introduced by
IBM in 1970s, which is totally corresponding to the OSI reference model. To realize
the trans-WAN transmission of SNA protocol, one of the solutions is the DLSw
technique.
The DLSw performance mechanism is shown in the following figure:
Figure 117 The DLSw mechanism diagram
As shown above, the frame in LLC2 format of local SNA device is transformed into
SSP frame encapsulated in TCP packet by the router running the DLSw protocol.
Across WAN through TCP channel, it is forwarded to remote end, where the SSP
frame is retransformed into related LLC2 frame and forwarded to the remote SNA
device. Obviously, the DLSw makes the local terminal equipment “believe” that
the remote device is in the same network with it. Different from the transparent
bridge, however, the DLSw does not transparently transmit the previous LLC2
frame directly to the peer end. Rather, it transforms the LLC2 frame into SSP frame
to achieve the encapsulation in TCP packet of the previous data. By virtue of its
local response mechanism, the DLSw can reduce unnecessary data transmission
(confirming frame and keeping active frame), and tackle the problem of data link
control timeout.
SSP frame encapsulated in TCP packet by the router running the DLSw protocol.
Across WAN through TCP channel, it is forwarded to remote end, where the SSP
frame is retransformed into related LLC2 frame and forwarded to the remote SNA
device. Obviously, the DLSw makes the local terminal equipment “believe” that
the remote device is in the same network with it. Different from the transparent
bridge, however, the DLSw does not transparently transmit the previous LLC2
frame directly to the peer end. Rather, it transforms the LLC2 frame into SSP frame
to achieve the encapsulation in TCP packet of the previous data. By virtue of its
local response mechanism, the DLSw can reduce unnecessary data transmission
(confirming frame and keeping active frame), and tackle the problem of data link
control timeout.
The trans-TCP/IP transmission of SDLC (Synchronous Data Link Control) protocol
can be realized by employing the DLSw technique in the following steps: first,
transform the SDLC packet into LLC2 (Logical Link Control, type 2) packet; then
interconnect with the remote end through the DLSw. In this way, the DLSw can
also support the interconnection of different media between LAN and SDLC.
can be realized by employing the DLSw technique in the following steps: first,
transform the SDLC packet into LLC2 (Logical Link Control, type 2) packet; then
interconnect with the remote end through the DLSw. In this way, the DLSw can
also support the interconnection of different media between LAN and SDLC.
DLSw Configuration
The DLSw configuration includes:
■
Create the local DLSw peer
■
Create the remote DLSw peer
■
Configure the bridge group connected with the DLSw
■
Configure the timer parameters of the DLSw
End System
TCP/IP
SSP
DLSw
DLSw
LAN
LLC2
LAN
LLC2
End System