IEEE 802.1ag

IEEE 802.1ag (also CFM) (IEEE Standard for Local and Metropolitan Area Networks Virtual Bridged Local Area Networks Amendment 5: Connectivity Fault Management) is a standard defined by IEEE. It defines protocols and practices for OAM (Operations, Administration, and Maintenance) for paths through 802.1 bridges and local area networks (LANs). It is an amendment to IEEE 802.1Q-2005 and was approved in 2007.

IEEE 802.1ag is largely identical with ITU-T Recommendation Y.1731, which additionally addresses performance monitoring.

The standard:

  • Defines maintenance domains, their constituent maintenance points, and the managed objects required to create and administer them
  • Defines the relationship between maintenance domains and the services offered by VLAN-aware bridges and provider bridges
  • Describes the protocols and procedures used by maintenance points to maintain and diagnose connectivity faults within a maintenance domain;
  • Provides means for future expansion of the capabilities of maintenance points and their protocols
  • 2-Arachidonoylglycerol

    2-Arachidonoylglycerol (2-AG) is an endocannabinoid, an endogenous agonist of the CB1 receptor. It is an ester formed from the omega-6 fatty acid arachidonic acid and glycerol. It is present at relatively high levels in the central nervous system, with cannabinoid neuromodulatory effects. It has been found in maternal bovine and human milk. The chemical was first described in 1994-1995, although it had been discovered some time before that. The activities of Phospholipase C (PLC) and diacylglycerol lipase (DAGL) mediate its formation. 2-AG is synthesized from arachidonic acid-containing diacylglycerol (DAG).

    Occurrence

    2-AG, unlike anandamide (another endocannabinoid), is present at relatively high levels in the central nervous system; it is the most abundant molecular species of monoacylglycerol found in mouse and rat brain (~5-10 nmol/g tissue). Detection of 2-AG in brain tissue is complicated by the relative ease of its isomerization to 1-AG during standard lipid extraction conditions. It has been found in maternal bovine as well as human milk.

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