Sun Microsystems SunLink SNA 9.1 PU2.1, Руководство по настройке

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C-10 SunLink SNA 9.1 PU2.1 Server Configuration Guide—August 1997
C
C.3 PU2.1 and PU2 Nodes
PU2.1 is a superset of PU2. Applications that previously depended on PU2 for
SNA support, such as 3270 and 3770, also work with PU2.1. From the
perspective of the host, the only difference is the initial preconnection transmit
and receipt of special information packets known as Exchange Identifier
Format (XID). XID packets convey the identification and characteristics of the
transmitting node before link contact is established. This helps to reduce the
configuration information systems need to connect to one another.
SNA hosts that had in the past been in hierarchical networks now support
peer-to-peer operation with PU2.1 nodes. VTAM and NCP now support the
definition of independent LUs.
The Sun PU2.1 SNA Server can communicate with a host in the traditional
manner, can communicate with a host in the peer manner, and can
communicate with a peer simultaneously over any of the supported link
protocols. This allows 3270 displays, CICS applications, and customized
LUType 6.2 TPs to operate concurrently.
C.4 LEN and APPN
To connect PU2.1 nodes within a peer-to-peer SNA network, you can use Low
Entry Networking (LEN) or Advanced Peer-to-Peer Networking (APPN). A
PU2.1 node can be an end node (EN) or a network node (NN), as follows:
•
Network node - Provides connectivity among other NNs and ENs. This
connectivity includes intermediate session routing, adaptive session-level
pacing, transmission priority, directory services, and topology and route
selection. Only APPN supports NNs.
•
End node - Can connect with a network node or with another end node.
Both APPN and LEN support ENs. APPN ENs, when connected with NNs,
can receive network connectivity information through a CP-CP session. LEN
ENs, on the other hand, must maintain this information statistically,
although they can still use many of the connectivity services of the NNs. An
example organization of APPN network nodes, with APPN end nodes and
LEN end nodes, is shown in the following figure.