IEEE 802.1ah is an amendment to the
IEEE 802.1Q
IEEE 802.1Q, often referred to as Dot1q, is the computer network, networking standard that supports virtual local area networking (VLANs) on an IEEE 802.3 Ethernet network. The standard defines a system of VLAN tagging for Ethernet frames and the ...
networking
Network, networking and networked may refer to:
Science and technology
* Network theory, the study of graphs as a representation of relations between discrete objects
* Network science, an academic field that studies complex networks
Mathematics
...
standard which adds support for Provider Backbone Bridges. It includes an architecture and a set of protocols for routing over a provider's network, allowing interconnection of multiple
provider bridge network
IEEE 802.1ad is an amendment to the IEEE 802.1Q-1998 networking standard which adds support for provider bridges. It was incorporated into the base 802.1Q standard in 2011. The technique specified by the standard is known informally as stacked ...
s without losing each customer's individually defined
VLAN
A virtual local area network (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer ( OSI layer 2).IEEE 802.1Q-2011, ''1.4 VLAN aims and benefits'' In this context, virtual refers to a ...
s. It was initially created by
Nortel
Nortel Networks Corporation (Nortel), formerly Northern Telecom Limited, was a Canadian Multinational corporation, multinational telecommunications and data networking equipment manufacturer headquartered in Ottawa, Ontario. It was founded in ...
before being submitted to the
IEEE 802.1 committee for standardization. The final version was approved by the
IEEE
The Institute of Electrical and Electronics Engineers (IEEE) is an American 501(c)(3) organization, 501(c)(3) public charity professional organization for electrical engineering, electronics engineering, and other related disciplines.
The IEEE ...
in June 2008 and has been integrated into IEEE 802.1Q-2011.
History
The now-ubiquitous
Ethernet
Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...
was initially defined as a
local area network
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. LANs facilitate the distribution of da ...
(LAN) technology to interconnect the computers within a small organization in which these host computers were very close in proximity to each other. Over the years, Ethernet has become such a popular technology that it became the default Data Link Layer (OSI Layer 2) mechanism for data transport. This created a need for extending the Ethernet from a customer LAN bridging domain to service provider MAN, also known as the Provider bridging domain. For this, a 4 byte S-Tag or Service Tag, a type of Virtual LAN tag, was added to the header of the Ethernet frame in
IEEE 802.1ad
IEEE 802.1ad is an amendment to the IEEE 802.1Q-1998 computer network, networking standard which adds support for provider bridges. It was incorporated into the base 802.1Q standard in 2011. The technique specified by the standard is known inf ...
standard. In the service provider domain, switching was based on S-Tag and destination MAC address, and C-tag was used to create virtual LAN within the customer domain. This technology is also known as QinQ or Q-tunneling.
QinQ does not offer true separation of customer and provider domains but is merely a way to overcome the limitations on the VLAN identifier space. It can also help in separation of the customer and provider control domains when used with other features like control protocol tunneling or Per-VLAN Spanning Tree etc. There is still the problem of having too little control on the MAC addresses, since QinQ forwarding is still based on the customer destination addresses. Thus, better mechanisms are needed.
Description
The idea of PBB is to offer complete separation of customer and provider domains. For this purpose, a new Ethernet header has been defined. This header may take multiple different forms, but the main components of the header are:
;
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;
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;
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:;
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;
;
;
The bridges in the PBB domain switch based on the B-VID and B-DA values, which contain 60 bits total. Bridges learn based on the B-SA and ingress port value and hence is completely unaware of the customer MAC addresses. I-SID allows distinguishing the services within a PBB domain.
PBB is the foundation for the
IEEE 802.1Qay PBB-TE standard, which was standardized in 2009.
PBB is sometimes referred to as MAC-in-MAC.
See also
*
Carrier Ethernet
Carrier Ethernet is a marketing term for extensions to Ethernet for communications service providers that utilize Ethernet technology in their networks.
Background
Ethernet has a long history. It has become dominant in enterprise networks. This d ...
*
IEEE 802.1
*
IEEE 802.1aq, Shortest Path Bridging
*
Metro Ethernet
A metropolitan-area Ethernet, Ethernet MAN, carrier Ethernet or metro Ethernet network is a metropolitan area network (MAN) that is based on Ethernet standards. It is commonly used to connect subscribers to a larger service network or for intern ...
References
External links
*http://www.ieee802.org/1/pages/802.1ah.html
The right transport foundation for carrier Ethernet services
{{IEEE standards
IEEE 802
Ethernet standards
Telecommunication protocols