Verilink 9000 Series (34-00271) Product Manual - Manual (Page 265)

14
IP PAD A
PPLICATION
P
ARAMETERS
Introduction This chapter provides specific information for the IP PAD application and how it
operates using the TXPORT MultiPro platform and NMCS software.
IP PAD
Basics The IP PAD is a new TXPORT product added to the broad variety of transport
protocols available from TXPORT. As with X.25 and frame relay, the IP PAD
product allows a network manager to use its existing IP backbone to transport its
legacy protocols encapsulated in an IP frame. As with X.25 and frame relay
TXPORT implementations, the IP PAD provides a reliable and connection-oriented
service to all of its legacy protocol suites.
By defining a list of remote IP PADs in its network, the network manager creates a
virtual link between multiple TXPORT units. By definition, the IP layer has no
connections and is unreliable (as is a frame relay backbone). To prevent
information loss, the TXPORT implementation uses the Packet Layer Protocol
(PLP) on top of the virtual IP link. This provides all the robustness and the error
recovery needed by the legacy protocols. In addition to those benefits, the PLP
layer allows the concatenation of multiple legacy protocols on the same virtual
link. Moreover each terminal uses its own logical channel on the virtual link,
preventing the degradation of performance of all terminals in case of a
bandwidth-eating application.
The IP PAD can work with an existing IP backbone using routers since NMCS
supports the configuration of a list of routers at the IP layer (see the IP Layer
chapter beginning on page 259) and redirects ICMP messages recognized by the
the IP layer.
Figure 14-3 on page 249 shows a typical IP PAD application.