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38 Chapter 1: Introduction to the EIU
297-8991-910 Standard 03.01 August 1999
TCP
Each TCP connection has its own state machine. For the number of allowed
connections, refer to Table 5, TCP connection limits by Supernode subsystem
in this document. There are also SOS limitations in that applications that
require hundreds or thousands of connections are not supported.
Internet Protocol and Internet Control Message Protocol
When an EIU goes ManB or SysB, any qualifying EIU that is available takes
over. The first EIU that failed broadcasts reverse-RIP messages advertising its
loss-of-connectivity to the network. In this way, the routers on the LAN that
are immediately notified of the second EIU takeover.
However, there is a worse case scenario in which the reverse-RIP messages are
lost on the LAN. As a result, the entry for the first EIU must time-out in the
routing table in each router before these routers start sending datagrams to the
second EIU. This time-out can take up to 3 min. This limitation is imposed by
the RIP implementation on the EIU. A possible option is to configure the
routers on the LAN to use only address resolution protocol (ARP) and not RIP
to communicate with the DMS-100 switch. However, the ARP-cache time-out
on the router must be set to a low value (1 min is the recommended time).
All subnet size combinations are permitted in table IPNETWRK. However, the
subnet size in the DMS-100 switch must be the same as the subnet size of the
LAN to which the DMS-100 switch is connected. This requirement is a result
of the limitation of the RIP version 1.0 implementation in the EIU. The IP
subnet must be allocated for each DMS-100 switch. Refer to “Addressing” on
page 50.
Feature packaging
Feature packaging applies to software loaded on the DMS-core. In general,
these packages provide the central maintenance functionality for the new
remote processors and the protocol software.
Prior to CSP02, the feature packages for the software resident in the DMS-core
are summarized in table 1.
Table 1 DMS-Core feature packages
Package Title Description
NTXF05AA Ethernet interface unit The is the basic package
needed to datafill and
maintain the EIU. No protocol
software is included in this
package.
(Sheet 1 of 2)