802.3Ah Grace Announcement - Alcatel-Lucent 7750 Configuration Manual

Interface Configuration

802.3ah Grace Announcement

A vendor-specific Grace TLV will be included in the Information PDU generated as part of the
802.3ah OAM protocol when a network element undergoes an ISSU function. Nodes that support
the Soft Rest messaging functions will allow the local node to generate the grace TLV.
The grace TLV is used to inform a remote peer that the negotiated interval and multiplier should
be ignored and the new 900s timeout interval should be used to timeout the session. The peer
receiving the Grace TLV must be able to parse and process the vendor specific messaging.
The new command grace-tx-enable has been introduced to enable this functionality. This
command exists at two levels of the hierarchy, system level and port level. By default this
functionality is enabled on the port. At the system level this command defaults to disabled. In
order to enable this functionality both the port and the system commands must be enabled. If
either is not enabled then the combination will not allow those ports to generate the vendor
specific Grace TLV. This functionality must be enabled at both the system and port level prior to
the ISSU or soft reset function. If this is enabled during a soft reset or after the ISSU function is
already in progress it will have no affect during that window. Both Passive and Active 802.3ah
OAM peers can generate the Grace TVL as part of the informational PDU.
There is no command to enable this on the receiving node. As long as the receiver understands and
can parse the Grace TLV it will enter the grace mode of operation.
The basic protocol flow below helps demonstrate the interaction between passive-active and
active-active peer combinations supporting the Grace TLV. In the first diagram the passive node is
entering an ISSU on a node that supports soft reset capabilities.
7750 SR Interface Configuration Guide Page 163