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Key Technologies of PTN - PWE3

Key Technologies of PTN - PWE3. V1.1. Contents. Introduction to PWE3 Technology PWE3 Service Bearing. What is PWE3?.

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Key Technologies of PTN - PWE3

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  1. Key Technologies of PTN - PWE3 V1.1

  2. Contents Introduction to PWE3 Technology PWE3 Service Bearing

  3. What is PWE3? PWE3 (Pseudo Wire Edge to Edge Emulation), also called as VLL (Virtual Leased Line), is a service emulation mechanism. It specifies the standards for providing the emulation service on specific PSN of IETF, including the standards of encapsulation, transmission, control, management, interconnection and security. PWE3 is used to emulate the basic features of telecom network services on the packet switching network. It can traverse the PSN with minimum impact on the performance, but it doesn't replay the emulated service perfectly. In plain terms, PWE3 is used to build a "channel" on the PSN to implement the emulation and transmission of services.

  4. Why we need PWE3? Demand from the Operators: The telecom Operators need a unified network service platform to support unified planning/construction/operation/management and maintenance. Trend of network development: converged and optimized PSN, with the capabilities of traffic engineering/service classification/QoS. The telecom operators need to construct and maintain network services with high ROI: Currently, the ROI of FR/TDM leased service is still higher than that of the Internet accessing service, but the fundamental network structure is in PSN type. The network services are interconnected and backward compatible. The Operators have constructed a lot of TDM service facilities, they want to protect their investment and get the maximum benefits of the facilities. So we need a technology to smoothly deliver the FR/TDM service on the PSN network and continue to get the benefits of the FR/TDM service. The PWE3 technology is just invented for this purpose.

  5. Functions of PWE3 Encapsulate the bit-streams of the cell, PDU or specific service at the input port Transmit the bit-streams via the IP or MPLS network; Create the PW at the ends of the tunnel, switch and assign the PW IDs; Manage the service-related information at the PW border, such as signaling, timing and sequence; Manage the alarms and status of the service.

  6. Tunnel provides edge to edge connection (between NNI ports of PE)，PW is created at the ends of the tunnel to encapsulate and deliver the services. The user's packets are encapsulated to be PW PD and transmitted via the tunnel. From the perspective of the customer equipment, the PW is a link or circuit that is exclusively occupied by specific service. Different services are carried by different PWs. This emulated circuit is called as Service Emulation. PW is invisible inside PTN. The network element at one end doesn't need to worry whether the element at the other end is the same type of network. The PE is responsible to conduct the encapsulation/de-capsulation of the service, manage the signaling, timing, sequence information of the PW border, manage the alarms and status of the service, and maintain the attributes and features of the service. The CE cannot feel the core network and will process the services as local services. NNI Pseudo Wire Tunnel PE1 PTN network PE2 CE1 PWE3 module CE2 PWE3 module Tunnel PW Emulation Principle of PWE3 PW emulation service

  7. PWE3 Intelligent Service Perception • Service sensing is useful for adopting suitable scheduling mode according to • the priority level of the service. • For ATM service, service sensing is based on the cell, the VPI/VCI ID mapped to different PW for processing, the priority (including the priority of dropping) can be mapped to the EXP field of the PW. • For Ethernet service, service sensing is based on outer VLAN ID or IP DSCP. • For TDM real-time service that is more sensitive to delay, the service is quickly forwarded by fixed rate. BTS BSC P PE PE NodeB RNC TDM E1 PWE3 EF ATM PWE3 AF1~AF4 Ethernet PWE3 BE

  8. PW provides an emulated physical or virtual link for the remote peer layer. The local service PDUs are encapsulated by the sending end PE and transmitted via the PSN. The receiving end PE peels off the encapsulation and releases the PDUs to the original format. Then the PDUs are sent to the destination CE. Emulation service, such as TDM, ATM Emulation service, such as TDM, ATM Emulation service Payload encapsulation Payload encapsulation PW PW multiplexing PSN tunnel PSN Physical layer PW multiplexing PSN tunnel PSN Physical layer PSN tunnel PWE3 Protocol Stack Model

  9. PWE3 Protocol Stack Model PWE3 only provides 3 layers of functions of the protocol layer model, including the encapsulation layer, the PW duplex layer and the PSN convergence layer. The encapsulation layer mainly includes the frame sequence control, timing and segmented transmission. The segmented transmission is closely related with the frame sequence control. As an optional function of PWE3, the encapsulation can be omitted. After the service PDU is attached with the PW encapsulation and the PSN header information, if the packet length is larger than that of the MTU (Maximum Transmission Unit) supported by the PSN, the PW payload must be transmitted in segment at the entrance PE and be reorganized at the exit PE. The PSN convergence layer provides the needed enhancement function to guarantee the service and provides unified interfaces for the PW layer to make the PW be independent from the PSN. If the PSN layer can satisfy the needs of the service by itself, this layer can be empty.

  10. Reference Model of PWE3 Emulated Service Pseudo Wire PSN Tunnel Tunnel AC AC PE1 PE2 CE1 CE2 Customer Edge 1 Provider Edge 2 Provider Edge 1 Customer Edge 2 Native Service Native Service

  11. Basic Network Components of PWE3 Access Circuit Pseudo Wire Forwarders Tunnels Encapsulation PW signaling protocol Quality of Service

  12. Basic Network Components of PWE3 AC (Access Circuit) The access circuit is the connection circuit or virtual circuit between the CE and PE. Generally, all the user packets on the AC, including the layer 2 and layer 3 protocol packets should be completely forwarded to the peer end. PW (Pseudo Wire) In simple words, the virtual connection is the combination of the virtual circuit and the tunnels. The tunnel can be LSP, L2TPV3 or TE. The virtual connection is directional. In order to create the virtual connection in PWE3, you need to transmit the VC information via the LDP or RSVP signaling, and combine the VC information with the tunnel management to form a PV. For the PWE3 system, the PW is like a direct connection channel between the local AC and the peer end AC, and it completes the transparent delivery of the layer-2 data of the user. In simple words, one PW represents one service.

  13. Basic Network Components of PWE3 Forwarders After the PE receives the data frames from the AC, the forwarder will select the PW for forwarding the packets, i.e. the forwarder will assign the PW labels. Actually, the forwarder is the forwarding table of PWE3. Tunnels The tunnel is used to bear the PW. One tunnel can bear multiple PWs. Generally, the tunnels in PWE3 are MPLS tunnels. The tunnel is a direct connection channel between the local PE and the peer end PE. It is used to complete the transparent delivery of data between the PEs.

  14. Basic Network Components of PWE3 Encapsulation The PW adopts standard encapsulation format and technology to transmit the packets. You can refer to "draft-ietf-pwe3-iana-allocation-X" for the detailed definitions of different types of PWE3 packet encapsulation. PW Signaling Protocol As the basis of PWE3, the PW signaling protocol is used to create and maintain the PW. Currently, there are mainly two types of PW signaling protocols: LDP and RSVP (supported by 6000 V2.0). Quality of Service The priority information contained in the header of the layer-2 packets are mapped to the priority of QoS on the public network.

  15. Contents Introduction to PWE3 Technology PWE3 Service Bearing

  16. Bi-directional Tunnel TDM PWE3 TDM PWE3 ATM PWE3 ATM PWE3 Eth PWE3 Eth PWE3 NodeB BSC/RNC PTN MSC/MGW BTS 6100/6200 6300 SR/BRAS Iub IMA E1 Iub Ethernet IP ATM STM-1 TDM E1 TDM E1 Ethernet Abis AAL2/5 802.1Q TDM ATM Abis ETH PWE3 PWE3 PWE3 TDM Abis Tunnel Tunnel Tunnel Iub E1 TDM PHY PHY PHY Iub IP E1 IP 802.1Q 802.1Q ETH ETH Iub AAL2/5 Iub ATM AAL2/5 IMA ATM E1 STM1 PWE3 Features: Unified Bearing of Multiple Services • PWE3 can support multiple interfaces, including TDM E1/ IMA E1/ POS STM-n/ chSTM-n/FE/GE/10GE; • PWE3 can realize unified bearing of the TDM, ATM/IMA, Ethernet services; • PWE3 provides unified packets transmission platform to reduce the CAPEX and OPEX.

  17. TDM to PWE3

  18. Bi-directional Tunnel E1 Abis E1 E1 P TDM Abis E1 E1 TDM E1 Implementation Process of TDM to PWE3 BTS1 PWE3 BTS1 PWE3 BTS1 E1 E1 BSC E1 E1 PE PE NodeB2 RNC TDM E1 Abis TDM E1 TDM PWE3 Tunnel PHY • PWE3 can support emulated transmission of traditional TDM services. TDM circuit emulation requires both ends of the PTN to support the interconnection function. At the entrance of the PTN, the TDM data are converted into a set of packets. At the exit of the PTN, the packets are restored to TDM circuit. • Provides unified packets transmission platform. • PWE3 is used to realize TDM service perception and configure the service according to the needs • TDM: Supports structured/unstructured emulation, as well as structured timeslot compression.

  19. Two Intelligent Modes of TDM E1 Processing TDM-E1/STM-N TDM-E1 PTN 6100/6200 NodeB 6300 RNC 1 For non-structured TDM E1, adopt transparent transmission to keep the integrity of E1 Services Aggregating Multiple E1 aggregated to a PW Multiple time slots aggregated to multiple PW 2 6100/ 6200 6300 NodeB Services recovery For structured TDM E1, provides idle timeslot compression to save the bandwidth resource

  20. ATM to PWE3

  21. Bi-directional Tunnel ATM ATM ATM P ATM Iub AAL Iub ATM AAL IMA ATM E1 STM1 Implementation Process of ATM to PWE3 NB2 ATM PWE3 NB2 ATM PWE3 • Provides unified packets transmission platform. • Realizes TDM service perception and configure the service according to the needs. • ATM/IMA: Supports VPI/VCI switching and idle cell removing. ATM BTS1 BSC ATM ATM ATM PE PE NodeB2 RNC IMA E1 Iub ATM STM-1 AAL ATM PWE3 Tunnel PHY

  22. Bi-directional Tunnel NB2 HSDPA PWE3 NB2 HSDPA PWE3 ETH ETH Iub Iub IP IP 802.1Q 802.1Q ETH ETH ETH to PWE3 ETH B PE ETH ETH A PE ETH ETH C PE Iub Ethernet Ethernet IP 802.1Q ETH PWE3 Tunnel PHY • Supports emulated transmission of ETH services. • Provides unified packets transmission platform. • Supports the E-LINE, E-LAN and E-TREE services.

  23. Ethernet Service Types E-Line service E-LAN service P-t-P EVC MP-t-MP EVC UNI UNI PTN CE CE PTN E-Tree service Leaf Root Leaf PTN Leaf Rooted P-t-MP EVC

  24. Ethernet service: E-Line E-Line service • The E-Line service is a point-to-point service. The connectivity is decided by the two points. The access point of the customer is called as UNI. According to the definition given by MEF, the E-Line service is a "Point-to-Point EVC" service. • The E-Line service falls into two types: EPL and EVPL. The major difference between the two types is that in the EPL service, the EVC is assigned only according to the UNI port, while in the EVPL service, the EVC is assigned according to both the UNI port and the CEVLAN.

  25. P-t-P EVC UNI NNI NNI UNI PTN CE CE PE PE EPL Service • The UNI port cannot be multiplexed. • One UNI port of the PE device can be accessed by one user only. • The users accessing the UNI ports are not distinguished via different VLANs. • The PE-PE connection is guaranteed with Qos. • When different services are transmitted between the PE devices, the bandwidths of the services are guaranteed. • The Ethernet connection between the PE devices adopts P-t-P connection.

  26. P-t-P EVC • Customer1：VLAN1001 • Customer2：VLAN1002 • Customer1：VLAN1001 • Customer2：VLAN1002 UNI NNI NNI UNI PTN CE CE PE PE EVPL Service • The UNI port can be multiplexed. • One UNI port of the PE device can be accessed by multiple users. • The users are distinguished via different VLANs. • The Ethernet connection between the PE devices adopts P-t-P connection.

  27. Ethernet Srvice: E-LAN E-LAN service • The E-LAN service is a point-to-multipoint service. The connectivity is decided by the points. The access point of the customer is called as UNI. According to the definition given by MEF, E-LANis a Multipoint-to-Multipoint EVC . • The E-LAN service falls into two types: EPLAN and EVPLAN. The major difference between the two types is that in the EPLAN service, the EVC is assigned only according to the UNI port, while in the EVPLAN service, the EVC is assigned according to both the UNI port and the CEVLAN.

  28. MP-t-MP EVC PTN EPLAN Service • The UNI port cannot be multiplexed. • One UNI port of the PE device can be accessed by one user only. • The users accessing the UNI ports are not distinguished via different VLANs. • The PE-PE connection is guaranteed with Qos. • When different services are transmitted between the PE devices, the bandwidths of the services are guaranteed. • The Ethernet connection between the PE devices adopts MP-t-MP connection.

  29. Customer2：VLAN1002 MP-t-MP EVC • Customer2：VLAN1002 • Customer1：VLAN1001 • Customer2：VLAN1002 PTN • Customer1：VLAN1001 • Customer2：VLAN1002 Customer1 EVC • Customer1：VLAN1001 Customer2 EVC EVPLAN Service • The UNI port can be multiplexed. • One UNI port of the PE device can be accessed by multiple users. • The users are distinguished via different VLANs. • The Ethernet connection between the PE devices adopts MP-t-MP connection.

  30. Ethernet Srvice: E-Tree E-Tree service • The E-Tree service is a point-to-multipoint service. The connectivity is decided by the points. The access point of the customer is called as UNI. According to the definition given by the MEF, the E-Tree service is a "Point-to-Multipoint EVC" service. In the E-TREE service, the UNI ports are classified as Root UNI and Leaf UNI. The Root UNI can communicate with the other Root UNIs and the Leaf UNIs. The Leaf UNI can only communicate with the Root UNIs. • The E-Tree service falls into two types: EPTree and EVPTree. The major difference between the two types is that in the EPTree service, the EVC is assigned only according to the UNI port, while in the EVPTree service, the EVC is assigned according to both the UNI port and the CEVLAN.

  31. Leaf Root Leaf PTN Leaf Rooted P-t-MP EVC EPTREE Service • The UNI port cannot be multiplexed. • One UNI port of the PE device can be accessed by one user only. • The users accessing the UNI ports are not distinguished via different VLANs. • The PE-PE connection is guaranteed with Qos. • When different services are transmitted between the PE devices, the bandwidths of the services are guaranteed. • The Ethernet connection between the PE devices adopts P-t-MP connection.

  32. Customer 1：VLAN 1001 • Customer 2：VLAN 1002 Leaf • Customer 1：VLAN 1001 • Customer 2：VLAN 1002 Root • Customer 1：VLAN 1001 Leaf PTN Leaf • Customer 1：VLAN 1001 • Customer 2：VLAN 1002 Rooted P-t-MP EVC Customer 1 EVC Customer 2 EVC EVPTREE Service • The UNI port can be multiplexed. • One UNI port of the PE device can be accessed by multiple users. • The users are distinguished via different VLANs. • The Ethernet connection between the PE devices adopts P-t-MP connection.

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