Expand Configuration and Management Manual (G06.24+)

Planning a Network Design
Expand Configuration and Management Manual—523347-008
3-6
ServerNet Connections
The major benefits of Expand-over-ATM connections are
•
Flexibility. No modifications need to be made to Expand applications to allow them
to run over ATM networks. A NonStop server that can access an ATM network can
be part of the Expand network.
•
Fault-tolerance. You can use the multi-line path feature to enhance the reliability of
Expand-over-ATM connections. Using this feature, you can configure up to eight
parallel lines between nodes.
•
High-speed connectivity and increased throughput. The ATM subsystem supports
the ATM User-Network Interface (UNI) Specification Version 3.0 over a 155 Mbps
SONET STS-3c connection.
•
Passthrough capability. Packets sent over an ATM network path can be forwarded
to another Expand line-handler process, which can be a different line type and in a
different processor.
ServerNet Connections
The Expand-over-ServerNet line-handler process provides connectivity to a ServerNet
cluster, which uses this process to provide a very high speed proprietary interconnect
between systems over a limited geographic range.
The Expand-over-ServerNet line-handler process accesses the network access
method (NAM) interface of the ServerNet cluster monitor process, $ZZSCL. The major
benefits of connections using ServerNet clusters are
•
Faster transmission speed and larger packet sizes. The ServerNet II cluster switch
uses router-2 technology, which provides crossbar wormhole routing of ServerNet
packets between 12 input ports and 12 output ports. (The ServerNet I cluster
switch is not supported.)
•
Fault-tolerance. The ServerNet cluster uses one ServerNet II cluster switch for the
X fabric and one ServerNet II cluster switch for the Y fabric. These two cluster
switches can support up to eight nodes. For fault-tolerance, each node connects to
both cluster switches.
•
Connectivity. ServerNet clusters can coexist with FOX rings, ATM or IP networks,
and other WAN and LAN products.
•
Manageability. The ServerNet cluster’s quick-disconnect capability makes it easier
to implement planned outages.
An Expand-over-ServerNet line-handler process can be configured as a single line
only; Expand-over-ServerNet lines cannot participate as a member of a multi-CPU path
(superpath).
Refer to Time Factors and Pathchange Messages on page 18-24 for information on
adjusting settings so that routing is optimal.