Provider bridge (802.1ad) Learning Summary

Provider bridge (802.1ad) Learning Summary The 802.1ad Specification defines carrier switches (called provide bridge in the Specification document ). The carrier network can also use virtual bridged LAN (VLAN) to provide services to users. A switch in a carrier's network is called a carrier's switch. A carrier's switch is equivalent to a user's switch (the mac bridge defined in customer bridge and 802.1d, And the vlan bridge defined in 802.1q is counted as customer bridge) there are some characteristics and requirements: 1. Different customers do not need any interoperability, and the interoperability between customers and service providers is also at least 2. The customer vlan (c-vlan) is defined) and service vlan (s-vlan). The vlan used by the user is differentiated from the vlan used by the carrier. The carrier provides services to the user through the s-vlan, independent Management of different users. 3. Users can independently allocate and manage the c-vlan. The c-vlan can be transparent to operators. The operator completely manages the s-vlan. 4. It defines several switches: user switches, also known as c-vlan switches, that is, mac switches and vlan switches. The User Switch has only one c-vlan component. A carrier switch, also called a s-vlan switch, has two types of carrier switches: a common carrier switch, which has only one s-vlan component; An Operator Edge switch, contains one s-vlan component and one or more c-vlan components Glossary: C-VLAN components: implements the user switch function of the logic module, can identify, add, delete c-vlan. C-VLAN bridge: vlan bridge customer: service provider service (service instance) purchaser Customer Bridge: mac bridge defined by 802.1d or vlan bridge defined by 802.1q Customer Edge Port (CEP ): the port connecting the user's Network on the C-VLAN component, a C-VLAN component has only one CEP Customer Network Port: s-the port connecting the user's Network on the vlan component, it can be either a physical port of the carrier's switch or an internal port of the carrier's edge switch. C-tagged service interface: determines the service and connectivity provided by the service instance: service provider to the user based on the c-tag. The s-vlan is used to represent the DEI: drop eligible indicator. When frames need to be discarded for queue management, frames whose DEI is true are discarded first. When DEI is false, the S-vlan component must support the VID translation table, just like common packets, the c-vlan component does not support the VID translation table. It is a two-way table that works in both the sending and receiving directions. It is used to create a ing between the local vid and the relay vid, the local vid is the service provided by the vid operator network in the frame to the user: the service mentioned here is different from the service represented in the protocol standard: the standard refers to the services provided by lower-layer protocols and up-layer protocols, which are embodied by service primitives and parameters. For example, the MAC Sub-layer provides MAC link layer services to the IP Sub-layer. The service here refers to the service provided by the operator to users, mainly for data connectivity. It is responsible for transmitting user data from one end of the operator's network to the other end, and ensuring the quality of service (QoS) 1. Service transparency the carrier network is transparent to data transmitted between users and user networks without modifying user data. The MAC service and media access method of the User Switch and end station are independent of the carrier's bridging network. However, it is not transparent to the media access method aggregation and media access method functions of the carrier network. provider bridge will terminate these functions of provider bridged network. The group mac address related to the carrier network is not transparent either. The User Switch cannot forward the reserved Multicast Of the provider bridged network. PEB often ends the reserved multicast of provider bridged network. The data sent and received by the provider bridge media access method is not forwarded by the user bridge, usually end on the pep port. 2. The user service interface operator can provide one or more service interfaces for the same user, each service interface provides different service selection, priority selection, and service access protection. 1) The user network port (CNP) of the s-vlan component on the port-based service interface provider bridge serves as the service interface. CNP provides a separate service interface. The user system can be a User Switch, router, or terminal device. You can connect to different services through different ports. The packets sent by the C-vlan aware user system to CNP do not contain the s-vlan, however, priority-tagged s-vlan 2 and c-tagged service interfaces can be provided by CEP of the c-vlan component of PEB. The c-tagged service interfaces are as follows: the C-tagged service interface provides service selection and identification through the c-vlan. Each datagram text sent by the user system is assigned a c-vlan, which is connected to a port-based service interface (CNP) the service interface between the S-vlan component and the c-vlan component is identified by the s-vid. Because each service interface corresponds to a service, the s-tag of the packets sent to the pep will be removed, the c-vlan allocates a PVID 3 for each untagged packet. The S-tagged service interface has the user-managed S-vlan bridge or the user-managed provide edge bridge (provides c-vlan components and CEP by yourself) 3. Service Isolation by providing one s-vlan for each service, the packets sent and received by PNP are both in s-vlan. 4. Service selection and identification port-based service interfaces: the service is selected by a unique CNP, and each CNP corresponds to a service, a pvid (s-vid) is assigned to CNP. The Acceptable Frame Type (Acceptable Frame Type) configured by CNP is) Admit Only Untagged and Priority-tagged frames 1) the port-based service interface directly uses the port pvid as the s-vid, regardless of tag 2 in the user input frame) the c-tagged service interface uses the c-vlan component to determine the Service Interface Based on the c-vid of the user input frame. The input frame is un-tagged and the service interface is determined based on the pvid of the port. Multiple c-vids can also correspond to one service interface. The Internal Service Interface corresponds to a unique s-vid (it can be understood that the internal service interface is a port-based service interface, the pvid is s-vid. The C-vlan component determines the difference between a service interface and a port-based service interface. The c-vlan component can modify the c-tag: add pvid as c-tag from the untag frame input by CEP, assign pvid as c-vid to the priority-tagged frame, or remove the c-tag of the frame from PEP, but it never forwards a frame without a c-tag. The Port-based service interface does not care whether the packet contains a c-tag or whether the c-tag is transparent to the port-based service interface. (3) The s-tagged service interface is determined by the user system. Because the frames sent by the user system already carry the s-vlan, the provider switch must carry the s-vlan, the access port can only be added to the s-vlan. Service Interface selection and identification functions are identified by server vlan tag type in EISS. 6. Service priority selection is based on port access: LAN priority signal indication or priority-tagged s-vlan priority based on c-tagged access: c-vlan-based pcp access based on s-tagged: s-vlan pcp VII. Service access protection service access protection refers to the user's access to multiple service interfaces through multiple LANs, so that multiple access LANs can be used for redundancy protection, when a device fails, the user can access the data loop normally. The disadvantage is that the user occupies the bandwidth of another user, and the operator limits the bandwidth of the user, A c-vlan component has only one CEP, but in the LAG scenario, CEP can have multiple MAC addresses,