802.1ad

相关协议

1) 802.1Q Virtual Bridged Local Area Networks 2) 802.1ad Provider Bridges

A Bridge can be logically subdivided into the following components: ? S-VLAN component ? C-VLAN component

Bridges are classified into VLAN Bridge: CB: Customer Bridge or C-VLAN Bridge PEB: Provider Edge Bridg

PCB: Provider Core Bridge or S-VLAN Bridge

Provider Core Bridge integrates only one S-VLAN component. It is capable of providing single service on a port.

Provider Edge Bridge integrates one S-VLAN component with zero or many C-VLAN components as well as integrates each C-VLAN (up to 4094 C-VLANs) individually with a different S-VLAN (up to 4094 S-VLANs). ================================ Bridge-Port-Type CB PEB PCB -------------------------------------------------------- Customer Bridge Port (CBP) YES NO NO Customer Edge Port (CEP) NO YES NO Customer Network Port (CNP) NO YES YES Provider Network Port (PNP) NO YES YES ================================ An aid to remember the functions of the Bridge Port Types:

? Customer ports (CEPs, CNPs) face the customer network and connect to a single customer. ? Provider ports (PNPs) face the provider network.

? Edge port (CEPs) are on C-VLAN components and recognize C-tags.

? Network ports (CNPs, PNPs) are on S-VLAN components and recognize S-tags.

Customer service Interface

A service provider can offer a customer one or more types of service interfaces, each providing different capabilities for service selection, priority selection, and service access protection. Some service interfaces are provided by the service provider operating systems that include C-VLAN components, or by customer operating systems that include S-VLAN components.

Access to a given service instance can be provided through different types of customer service interface. 1) CNP-Port Based (Port-based service interface)

Traffic on this port is considered to be a single service and is assumed to have no S-tags. The port-based CNP applies a single S-tag for all customer traffic at ingress. The port-based CNP strips out the S-tag on egress to the Customer Bridge.

2) CNP-STAG(S-tagged service interface)

The S-tagged service interface is provided by a Provider Bridge to allow the attached customer to select between, and to identify service instances using the S-VID associated with the transmitted and received frames. The traffic on this port may have S-tags used by customer equipment to differentiate services. The customer-controlled provider edge bridge can provide C-Tagged service interfaces within the customer's own network. These customer-controlled Provider Bridges are connected to the provider-controlled bridges via CNP S-Tagged interfaces. The communication between the customer-controlled Provider Bridge and the connecting Provider Bridge is through SVLAN tag. 3) CEP(C-tagged service interface)

Configuring a port as Customer Edge Port results in creating a C-VLAN component. The C-VLAN component can be uniquely identified by the port number of the Customer Edge Port. A C-VLAN component in a Provider Edge Bridge integrates a single Customer Edge Port and many Provider Edge Ports.

Service instance selection is provided for C-tagged service interfaces by a C-VLAN component internal to a Provider Edge Bridge. The C-VLAN component uses the C-VID to direct frames to an internal Provider Edge Port supporting a specific service instance. C-VID Registration Table

The CVID Registration table provides mapping between a Customer VLAN and Service VLAN. Many Customer VLANs can be mapped to a single service instance (Service VLAN). Mapping first a Customer VLAN to a Service VLAN results in creating a Provider Edge Port (PEP). Provider Edge Ports are logical ports that are used to connect the C-VLAN component to the S-VLAN component. Provider Edge Ports are uniquely identified by a Customer Edge Port and a Service VLAN ID. This table provides the equivalent functionality of

1) Configuring the PVID of the internal Customer Network Port on the S-VLAN component;

2) Adding the corresponding Provider Edge Port on the C-VLAN component to the member set of the C-VLAN;

3) Adding the Provider Edge Port and/or Customer Edge Port to the untagged set of the C-VLAN (if it is desired that frames forwarded to that port are transmitted untagged for this C-VLAN). 举例：

CEP端口(5/2)加入到S-VID=6,7的S-VLAN。

从Customer侧过来的报文C-VID=1001,1002,2001,2002。

C-VID=1001,1002映射到S-VID=6; C-VID=2001,2002映射到S-VID=7. 具体如下表：

===================================== S-VLAN Port C-VLAN Untagged-PEP Untagged-CEP ----------------------------------------------------------- 6 Gi5/2 1001 False False 6 Gi5/2 1002 False False 7 Gi5/2 2001 False False 7 Gi5/2 2002 False False

===================================== 应当如下配置C-VID Registration Table。

输入：CEP端口号(5/2)，C-VID(1001, 1002, 2001, 2002) 1) 配置S-VLAN Component上的CNP-Port Based的PVID; CEP(5/2)内部生成2个PEP和2个CNP-Port Based。 2个CNP-Port Based的PVID分别设成6和7。 2) 把PEP加入到上述C-VLAN中;

Service VLAN-ID =6的PEP加入到C-VLAN=1001和1002的Member Set中。 Service VLAN-ID =7的PEP加入到C-VLAN=2001和2002的Member Set中。 结果如下：

---------------------------------------------------- Provider Edge Port configuration: Port Gi5/2

Service VLAN-ID : 6 Port VLAN-ID : 1001 Port Gi5/2

Service VLAN-ID : 7 Port VLAN-ID : 2001

---------------------------------------------------- 3) 设置PEP/CEP的端口Untagged属性 (true/false);

端口配置(Port Configuration)

a) PVID

Configuration of a PVID for each Port, to associate a VID with untagged and priority-tagged received frames

b) Default User Priority

An integer range 0-7 to be used for untagged frames received at the port;