X.25 337
Figure 10-7
XOT and STUN in the Core
Follow the packet:
The X.25 PAD device at Remote Site A establishes an X.25 connection to the PAD at Remote
Site B:
1
The PAD makes an X.25 call setup request, and Router Houston accepts the call setup
request via X.25.
2
Router Houston establishes an XOT connection to Router Dallas at the core site, and
Router Houston encapsulates the X.25 message into IP.
Proprietary protocol
X.25 Packet switch
X.25
Serial 0
Encap STUN
Interface ATM
Serial 1
Dashed lines represent XOT
packets
Router Dallas
Frame Relay
IP cloud
Access subnetwork
(ASN)
Remote Site A
X.25
Router Houston
Router Memphis
Remote Site B
Router Nashville
Interface ATM
Serial 0
Encap STUN
X.25
Serial 1
Proprietary protocol
X.25 Packet switch
ATM core
backbone sub
network
IP cloud
X.25
PAD
PAD
Frame Relay
IP cloud
Access subnetwork
(ASN)
Solid lines represent
STUN tunnels
87200333.book Page 337 Wednesday, August 22, 2001 2:53 PM