Explanation:
802.1ah PBB
802.1ad QinQ
802.1ag Connectivity fault management
Benefits of IEEE 802.1ah standard
The benefits of IEEE 802.1ah provider backbone bridges are as follows:
* Increased service instance scalability
* MAC address scalability
IEEE 802.1ah Standard for Provider Backbone Bridging Overview
The IEEE 802.1ah Provider Backbone Bridge feature encapsulates or decapsulates end user traffic on a Backbone Edge Bridge (BEB) at the edge of the Provider Backbone Bridged Network (PBBN). A Backbone Core Bridge (BCB) based network provides internal transport of the IEEE 802.1ah encapsulated frames within the PBBN.
Overview of OAM The advent of Ethernet as a metropolitan and wide-area networking technology has accelerated the need for a new set of OAM protocols. Service provider networks are large and complex with a wide user base, and they often involve different operators that must work together to provide end-to-end services to enterprise customers. While enterprise end-customer demands continue to increase, so do the requirements for service provider Ethernet networks, particularly in the areas of availability and mean time to repair (MTTR). Ethernet OAM addresses these challenges and more, thereby directly impacting the competitiveness of the service provider. Ethernet has been used as a LAN technology for many years, and enterprises have managed these networks effectively, primarily with the use of Internet protocols such as Simple Network Management Protocol (SNMP), ICMP Echo (or IP Ping), IP Traceroute, and Cisco Unidirectional Link Detection Protocol (UDLD) and Layer 2 Traceroute (supported in Cisco Catalyst® OS and some Cisco IOS® Software-based platforms). In addition to these troubleshooting protocols, Cisco provides a wealth of other configuration, fault, network management, and performance management tools. Cisco also supports MPLS OAM capabilities such as Virtual Circuit Connectivity Verification (VCCV) and Label Switched Path (LSP) ping on the Carrier Ethernet platforms. To complement these OAM capabilities and to ensure that Ethernet can deliver the required customer service-level agreements (SLAs), Cisco has developed comprehensive Ethernet and IP SLA agents, along with an embedded event manager (EEM), and IPTV video quality tools for automated measurement and troubleshooting of Carrier Ethernet deployments.
Ethernet OAM addresses the following challenges:
* The existing protocols mentioned earlier will not work unless the Ethernet layer is operating properly, making Ethernet OAM a prerequisite.
* Many service providers do not want to overlay an IP infrastructure simply for management and troubleshooting of Layer 2 Ethernet services.
* The current management protocols lack the per-customer or per-service granularity that is required to manage the individual Layer 2 Ethernet services provided to enterprises.
* The existing protocols do not assist with provisioning of Ethernet services, which is particularly difficult when the service provider and end customer must coordinate the configurations on their respective Ethernet equipment.
Ethernet OAM is a broad topic, but this paper will focus on three main areas of Ethernet OAM that are most in need by service providers and are rapidly evolving in the standards bodies: Service Layer OAM (IEEE 802.1ag Connectivity Fault Management), Link Layer OAM (IEEE 802.3ah OAM), and Ethernet Local Management Interface (MEF-16 E-LMI). Each of these different OAM protocols has unique objectives and is complementary to the others IEEE 802.1ad[note 1] is an Ethernet networking standard informally known as IEEE 802.1QinQ and is an amendment to IEEE standard IEEE 802.1Q-1998. The technique is also known as provider bridging, Stacked VLANs or simply QinQ or Q-in-Q.
The original 802.1Q specification allows a single VLAN header to be inserted into an Ethernet frame. QinQ allows multiple VLAN headers to be inserted into a single frame, an essential capability for implementing Metro Ethernet network topologies. Just as QinQ extends 802.1Q, QinQ itself is extended by other Metro Ethernet protocols.[specify] In a multiple VLAN header context, out of convenience the term "VLAN tag" or just "tag" for short is often used in place of "802.1Q VLAN header". QinQ allows multiple VLAN tags in an Ethernet frame; together these tags constitute a tag stack. When used in the context of an Ethernet frame, a QinQ frame is a frame that has 2 VLAN 802.1Q headers (double-tagged).
There is a mild confusion regarding the naming because the 802.1ad standard was grown out of the 802.1QinQ protocol (which was developed based the trademarked method 802.1Q, with capital "Q" as a distinction instead of the 802.1q as the standardised protocol) which originally used 0x9100 as ethernet type instead of 0x88a8. While the network industry usually mix the naming the proper, standardised name is 802.1ad which sometimes gets appended by the other alternative names mentioned above; the plain "802.1QinQ" name usually refers to the old standard which is now considered obsolete
