Extreme Networks Ridgeline 3.0, Руководство пользователя

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Ridgeline Concepts and Solutions Guide
113
C H A P T E R
8
Managing PBB Networks
Virtual metropolitan area networks (VMANs) allow metropolitan area network (MAN) service
providers to carry VLAN traffic from multiple customers across a common Ethernet network, known as
a
provider bridge network . The provider bridge network uses Provider Bridges (PBs) to create a Layer 2
network that supports VMAN traffic.
A Provider Backbone Bridge (PBB) network enables VMAN transport over the Internet. PBB is defined by
the IEEE 802.1ah Backbone Bridge standard, which is an amendment to the IEEE 802.1Q VLAN
standard. This standard allows Internet Service Providers (ISPs) to use Ethernet to create a separate
backbone over which the subscriber’s frames are transported. In a PBB network, data from multiple
subscriber networks travels over a common ISP backbone, with traffic from the individual subscriber
networks completely separate from each other.
Figure 73 shows a PBB network, which spans a set of ISP switches that serve as Provider Backbone
Bridges (PBBs).
Figure 73: PBB Network
You can view a PBB network as a Layer 2 network that supports VMAN traffic. The entry points to a
PBB network are the access ports on the PBB network edge switches. These ports are designed to
PBBN
vMAN
vMAN
vman_0002
Network
ports
(BVLAN)
Access
ports
(SVLAN or
CVLAN)
vMAN
access
ports
vMAN
access
ports
vMAN
network
ports
vMAN
network
ports
VLAN
traffic
VLAN
traffic
VLAN
traffic
VLAN
traffic
Access
ports
(SVLAN or
CVLAN)