I have created a short document to illustrate where LCAS is involved in the connection setup. (see attachment). In principle, LCAS isn't involved in connection set up or release. LCAS controls if a trail is being used to forward payload information. The set up and release of the trail is fully controlled by NMS/ASON/GMPLS. E.g. when the bandwidth of the client layer link that is supported by the virtual concatenated trail is to be increased, the network engineering controller will request this BANDWIDTH INCREASE. The Call Controller receiving this request will send a Connection Modification request for Connection X to the Connection Controller and it will send an ADD member command to the LCAS process within the virt conc port group. The ADD command is now forwarded over the VC-n port that will be the end point of the new VC-n trail. When this trail is set up, the LCAS process at the far end will receive the ADD command and will detect that the trail signal fail condition has cleared. It will reply with an OK message. When this OK message is received by the near end LCAS process, it will start forwarding payload information over this new trail (after it has send another message indicating the exact frame which will contain paylaod in it for the first time). Now the bandwidth is increased in one direction. The similar process is performed for the other direction. I.e. the far end virt conc port group receiving the Connection Modification request will also receive the ADD command (i.e. responsibility of the network engineering controller or call controller). The far end LCAS process will now issue the ADD command over the VC-n port that is the endpoint of the new trail. The near end LCAS process will at a certain moment receive the ADD command from the far end and when the associated trail signal fail condition clears, it will respond with the OK message. When this OK message arrives at the far end LCAS process, that process will start forwarding payload information over this new trail (after it has send another message indicating the exact frame which will contain paylaod in it for the first time). Up to so far. Regards, Maarten
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lcas-gmpls-pdf.zip
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