Provider Backbone Bridges (PBB) is a set of architecture and protocols for routing over a provider's network allowing interconnection of multiple

provider bridge network IEEE 802.1ad is an Ethernet networking standard. It is as an amendment to IEEE standard IEEE 802.1Q-1998 and was incorporated into the base 802.1Q standard in 2011. The technique specified by the standard is known as provider bridging and stac ...

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 ph ...

s. It was initially created by

Nortel Nortel Networks Corporation (Nortel), formerly Northern Telecom Limited, was a Canadian multinational telecommunications and data networking equipment manufacturer headquartered in Ottawa, Ontario, Canada. It was founded in Montreal, Quebec, ...

before being submitted to the

IEEE 802.1 IEEE 802.1 is a working group of the IEEE 802 project of the IEEE Standards Association. It is concerned with: * 802 LAN/MAN architecture * internetworking among 802 LANs, MANs and wide area networks * 802 Link Security * 802 overall network manage ...

committee for standardization. The final standard was approved by the

IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operat ...

in June 2008 as IEEE 802.1ah-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 1 ...

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, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...

(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 Ethernet networking standard. It is as an amendment to IEEE standard IEEE 802.1Q-1998 and was incorporated into the base 802.1Q standard in 2011. The technique specified by the standard is known as provider bridging and stac ...

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: * Backbone component, that has: ** Backbone destination address (B-DA) (six bytes) ** Backbone source address (B-SA) (six bytes) ** EtherType 0x88A8 (two bytes) ** B-TAG/B-VID (two bytes), this is the backbone VLAN indicator * Service encapsulation, which has: ** EtherType 0x88E7 (two bytes) ** Flags that contain priority, Drop Eligible Indicator (DEI) and No Customer Address (NCA) indication (e.g. OAM frames). ** I-SID, the service identifier (three bytes) * Original customer frame ** Customer destination address (six bytes) ** Customer source address (six bytes) ** EtherType 0x8100 (two bytes) ** Customer VLAN identifier (two bytes) ** EtherType (e.g. 0x0800) ** Customer payload PBB defines a 48-bit B-DA and 48-bit B-SA to indicate the backbone source and destination MAC addresses. It also defines a 12-bit B-VID (backbone VLAN ID) and 24-bit I-SID (Service Instance VLAN ID). 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.

References

External links

*http://www.ieee802.org/1/pages/802.1ah.html
The right transport foundation for carrier Ethernet services
{{IEEE standards

IEEE 802.1ah IEEE 802.1ah is an amendment to the IEEE 802.1Q networking 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 p ...

Ethernet standards Telecommunication protocols

History

Description

See also

References

External links