ASAI Maintenance Capabilities
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
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
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.
■The adjunct makes a Restart Request, without listing any link versions.
■The ECS responds with a Restart ACK, choosing link version 1.
