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ASAI Maintenance Capabilities
11-6 Issue 7 May 1998
sends a Restart Acknowledgement message insisting on a version not supported
by the ECS, the link is not initialized and an error is logged.
Adjuncts without the versions procedure are able to perform pre-G3V4 RESTART
procedures unchanged (in other words, RESTart — RESTart ACK). In these
cases, the ASAI link comes up with the default version.
1. ECS-initiated restart - Adjunct-supporting link versions
■ The ECS makes a Restart Request, listing the link versions that it
supports.
■ The adjunct responds with a Restart ACK, choosing one of the
supported versions.
■ The link is now in the “layer 3 restarted” state, and the link version is
set to the chosen version. The ECS then sends a heartbeat. If the
adjunct acknowledges (ACKs) the heartbeat, the link will go into the
“layer 3 established” state. This is the state in which the link is
operational. (See ‘‘Heartbeat’’ on page 11-2 in this chapter.)
2. ECS-initiated Restart - adjunct not supporting link versions
■ The ECS makes a Restart Request, listing the link versions that it
supports.
■ The adjunct responds with a Restart ACK, without specifying a link
version.
■ The link is now in the “layer 3 restarted” state, and the link version is
set to Version 1. The ECS then sends a heartbeat. If the adjunct
ACKs the heartbeat, the link will go into the “layer 3 established”
state. This is the state in which the link is operational. (See the
"Heartbeat" section in this chapter.)
3. Adjunct-initiated restart - ECS supports chosen link version
■ The adjunct makes a Restart Request, listing the link versions that it
supports.
■ The ECS responds with a Restart ACK, choosing one of the
supported versions. The ECS prefers higher link versions when
making the choice.
■ The link is now in the “layer 3 restarted” state. If the adjunct then
sends a heartbeat, the ECS will respond with a heartbeat ACK. At
that point, the link will go into the “layer 3 established” state.
4. Adjunct-initiated restart - adjunct not supporting link versions
■ The adjunct makes a Restart Request, without listing any link
versions.
■ The ECS responds with a Restart ACK, choosing link version 1.