Chapter 4: EIU maintenance 107
The EIU remained fully functional throughout the test. Although traffic from the EIU stopped, the stoppage was due to all other components on the LAN being
These test also showed that maintenance personnel could remote login to the EIU, start a CI process, look at OMs, and finally remote logout. The EIU could also successfully complete an
EIU sparing requirements
The EIU is a variation on the CCS7 link interface unit 7 (LIU7) that Nortel developed for the DMS signaling transfer point (STP). The central maintenance software for the EIU is based on the generic software developed for the LIU7. The local maintenance software for the EIC, the EIP, and the routing software are particular to the EIU.
EIUs are simplex entities and therefore require a sparing strategy to handle the following situations:
•hardware failure of an EIU
•batch change supplement (BCS) software upgrade on an EIU
•manual maintenance actions on an EIU
EIU sparing is established and operates as follows:
•The EIUs are organized in sets and lists based on routing information. All EIUs on a single LAN are a set. Multiple sets support multiple LANs.
•All SuperNode hosts (CM, FP, and application processor unit [APU]) have one list of EIUs from a set of lists. The EIUs on this list are configured to reach a specific subnet.
•If one of the EIUs in the list fails, the
•The TCP reliable transport protocol recovers from all but the most severe forms of failure. Most EIU failures are transparent to the end applications that is using the EIU as a router. Any applications fail if the EIU on which they reside fails.
•All EIUs are routers, hosts, or both. The sparing strategy allows only other routers as spares. An EIU as a host and router can be used if all other routers have failed. This sparing strategy has an impact on the host application performance. Applications running on the EIU itself require application level sparing to recover.
•All definitions for the sparing strategy are controlled with datafill.
