TCP/IP Tutorial and Technical Overview
X.25
Scenario using the IBM 9370
5.11 3745 and Ethernet Adapter
The 3745 when installed with an ESS (3745 Ethernet
SubSystem), and running the NCP (Network Control Program) Version 6, support
the routing of IP and ARP Ethernet traffic. Both Ethernet V2 and IEEE 802.3
frames are supported by the 3745 ESS. It supports communication from:
lEthernet IP workstation/host to Ethernet IP workstation/host
lEthernet IP workstation/host to VM/MVS TCP/IP host.
5.11.1 Principle of Operation
NCP IP routing uses SNA sessions to transport IP datagrams across an SNA
backbone network. SNA sessions are established from NCP IP nodes to other NCP
IP nodes and SNALINK TCP/IP hosts. IP datagrams are enveloped at an IP node
into an SNA RU and sent across an SNA session to a destination NCP IP node or
SNALINK TCP/IP host. The routing mechanism is based on static NCP routing
tables. The destination NCP IP node or SNALINK TCP/IP host de-envelopes the IP
datagrams and sends the frames to an Ethernet/802.3 LAN or a TCP/IP host
subsystem respectively. NCP also supports the TCP/IP Address Resolution
Protocol (ARP). IP traffic will benefit from NCP routing of IP within the SNA
backbone network (error recovery, flow control, etc.).
Figure: 3745 and Ethernet Adapter
5.11.2 Example
All the workstations can access a VTAM application in the host using TELNET.
All the workstations can access a TCP/IP application in the host (for
example FTP).
Workstation 1 can communicate with workstation 2 (Ethernet-to-Ethernet in
the same 3745).
Workstation 1 can communicate with workstation 3 (Ethernet-to-Ethernet in
different 3745s using the SNA backbone).
3174
Establishment Controller
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