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Tel-Aviv, May 2007 Pseudowires Solutions – Advanced Presented by: Merav Shenkar

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Presentation on theme: "Tel-Aviv, May 2007 Pseudowires Solutions – Advanced Presented by: Merav Shenkar"— Presentation transcript:

1 Tel-Aviv, May 2007 Pseudowires Solutions – Advanced Presented by: Merav Shenkar

2 PW Solutions Advanced TS2007 Slide 2 Agenda Introduction PW protocols for different services The PW Challenges PSN QoS Throughput & Delay PW OAM- connectivity confirmation Fault propagation Clock

3 PW Solutions Advanced TS2007 Slide 3

4 PW Solutions Advanced TS2007 Slide 4 TDM PW Services Unframed TDMoIP or SAToP over PSN E1/T1 line is a 2.048/1.544 Mbps bit stream Full transparency to the TDM traffic No Multi-Bundling End-to-End framing sync TDMoIP standard: IETF – ietf-pwe3-tdmoip SAToP standard: draft-ietf-pwe3-satop.txt- Structure-Agnostic TDM over Packet ETH PW-GW PBX ETH/IP/ MPLS Network

5 PW Solutions Advanced TS2007 Slide 5 TDM PW Services cont. Framed TDMoIP or CESoPSN Framed E1/T1 Multi-Bundling TS0/Fbit Termination Local framing sync TDMoIP standard: IETF – ietf-pwe3-tdmoip CESoPSN: draft-ietf-pwe3-cesopsn.txt - Structure-Aware TDM Circuit Emulation Service over PSN ETH PW-GW PBX Framing Sync PBX ETH/IP/ MPLS Network

6 PW Solutions Advanced TS2007 Slide 6 ETH (12) ETH type 0800 (2) IP Header (20) UDP Header (8) ETH (12) IP type 0800 (2) IP Header(20) ETH (12) MPLS type 8847 (2) Tunnel Label (4) TDM PW Encapsulation Format Overhead size: IP: 46 bytes MPLS: 30 bytes UDP: 50 bytes *HDLC encapsulation is done according to IP/MPLS: RFC 4618 PW label (4) TDM CW (4) PW label (4) IPIP MPLS UDP TDM/HDLC Payload CRC

7 PW Solutions Advanced TS2007 Slide 7 TDMoIP Payload Size TDMoIP Unframed/Framed payload size: is between bytes nx48 bytes (where n=1,2,3,……,30) CESoPSN & SAToP payload size: is between bytes according to the number of TS in a bundle(configurable) Payload configuration: N – Number of Time Slots in a bundle L – Packet payload size in bytes L should be multiple integer (m) of number of Time Slots in the bundle (N) L = m x N HDLCoIP mechanism monitors the data stream until a frame (data) is detected (flag) ETH IP UDP CW TDM/HDLC Payload CRC

8 PW Solutions Advanced TS2007 Slide 8 3G ATM Based Services ATMoPSN Mapping of ATM cells to packets Transparent backhaul of lub over packet based network End-to-End QoS is maintained 1:1 & n:1 mapping modes Standard: draft-IETF-PWE3-atm-encap ATMoPSN GW PSN RNC n × E1 IMA/ STM-1 Node B ATM

9 PW Solutions Advanced TS2007 Slide 9 ATMoPSN Overhead size: IP: 45 bytes MPLS: 29 bytes ETH(12) MPLS Type(2) Tunnel Label(4) PW Label (4) ATM* CW (3) Cell Header* ATM PayloadCRC (4) ETH(12) IP Type(2) IP Header(20) PW Label(4) ATM* CW(3) Cell Header* ATM Payload CRC (4) *Cell Header – In VCC mode – 1 byte per cell, In VPC mode – 3 bytes per cell Control word – Has a different format for each PW type (optional for some PW types)

10 PW Solutions Advanced TS2007 Slide 10 Multiple Cells Concatenation Format ATM Payload size Up to 29 cells in a single frame Cell concatenation reduces overhead ETH MPLS Type Tunnel Label PW Label ATM CW Cell Header* ATM Payload ATM CW Cell Header ATM Payload Cell Header ATM Payload Cell Header ATM Payload CRC

11 PW Solutions Advanced TS2007 Slide 11 Pseudowire Standards ApplicationStandardIETFProduct TDM PW TDMoIP Ietf-pwe3-tdmoip IPmux-11 IPmux-14 IPmux-8/16 Gmux-2000 LA-110 CESoPSN Ietf-pwe3-cesopsn ACE-3xxx LA-110 LA-130 SAToP draft-ietf-pwe3-satop ACE-3xxx LA-110 LA-130 ATMoPSNATM service transport ietf-pwe3-atm-encap ACE-3xxx LA-110 LA-130 HDLCoPSNHDLC transport RFC 4618 LA-110

12 PW Solutions Advanced TS2007 Slide 12

13 PW Solutions Advanced TS2007 Slide 13

14 PW Solutions Advanced TS2007 Slide 14 E1 VCC CBR UBR QoS over PSN Challenge: Traffic coming from the native services ports (ATM/TDM) contains a certain QoS which should be kept across the PSN Solution: The PSN GW scheduler should decide which packet will be sent first towards the PSN network “Convert” the native service priority into priority over PSN PSN PSN GW

15 PW Solutions Advanced TS2007 Slide 15 ETH Scheduling TX Queue Assignment User traffic priority should be also prioritized internally by the PW GW when transmitted to the PSN The internal prioritization will be done using ETH Tx queues with different priority levels The user should decide which service will get the highest priority within the PW-GW. for example: Clock traffic – highest priority Tx queue ETH data traffic – lowest priority queue

16 PW Solutions Advanced TS2007 Slide 16 PSN QoS TDM/ATM QoS are mapped to PSN QoS: Ethernet networks VLAN ID or VLAN priority VLAN can be optionally added to every encapsulation mode for CoS differentiation and QoS marking MPLS networks EXP bits of the MPLS label on both inner and outer label IP networks ToS/DSCP ToS bit marking per PW

17 PW Solutions Advanced TS2007 Slide 17

18 PW Solutions Advanced TS2007 Slide 18 Throughput & Delay Challenge: Encapsulating the native service payload over PSN transparently adds an overhead and delay Solution: Provide a mechanism to control PW bandwidth utilization and delay

19 PW Solutions Advanced TS2007 Slide 19 PSN Bandwidth Utilization The output BW of the PW GW is governed by setting the PW frame’s payload size. Typically the PW overhead introduced by the PW protocol has a fixed size, while the payload size is user configurable. Increasing the payload size would reduce the ratio between the overhead and the frame size. The larger the payload size the better smaller the BW utilization over the PSN. PW Frame Payload Header PW Frame Payload Header Payload

20 PW Solutions Advanced TS2007 Slide 20 Packetization Delay Packetization Delay (PD): The time it takes the PSN-GW to fill the payload with the incoming TDM/ATM traffic The larger the payload, the longer it will take to fill up and transmit the PW frame. The PD is the interval between two consecutive PW frames PW Frame Payload Overhead

21 PW Solutions Advanced TS2007 Slide 21 Triggers for Packet Transmission A PW frame will be sent towards the PSN under the following conditions: TDMoIP/CESoPSN/SAToP The configurable payload size is filled with TDM frames. ATMoPSN Payload is filled with ATM cells (1-29 cells per frame) The timeout mechanism expires (between 100 – Sec) Detection of AAL5 SDU bit=1 triggers packet transmission

22 PW Solutions Advanced TS2007 Slide 22 PD Vs. Bandwidth/PPS * This graph describes the BW consumption and PD values for a full Unframed E Mbps 0.2ms 5.5ms 2.2 Mbps

23 PW Solutions Advanced TS2007 Slide 23 TDMoIP Calculator

24 PW Solutions Advanced TS2007 Slide 24 CESoPSN & SAToP Calculator

25 PW Solutions Advanced TS2007 Slide 25 ATMoPSN Calculator

26 PW Solutions Advanced TS2007 Slide 26

27 PW Solutions Advanced TS2007 Slide 27 Connectivity Verification Challenge: PSN networks have no inherent connectivity verification mechanism between two end points. Solution: Provide path fault detection for an emulated PW over PSN Allow detecting faults occur on the remote end, in order to prevent IP/ETH network flooding Enable the use of redundancy

28 PW Solutions Advanced TS2007 Slide 28 TDM PWs* TDM PWs generate constant traffic over the PSN (regardless of the TDM traffic) Therefore, there is no need for “keep-alive” messages during steady state During device failure condition, we need to stop traffic transmission in order to prevent PSN flooding. The PW GW will initiate a “keep alive” messages based on TDMoIP OAM protocol, just in case a failure was detected * TDMoIP OAM – RAD’s proprietary Operation Administration and Maintenance protocol PW Wait 10 sec 5 OAM messages Failure PW-GW PSN Wait 2 sec for an answer and then stop transmission

29 PW Solutions Advanced TS2007 Slide 29 PW ATM PWs PW Declares state= down state = down BFD PW-GW PSN Since ATM PWs based on a statistical network, a keep alive messages are required in order to verify the PW connectivity. PW-GWs sends BFD messages messages periodically between PW, based on VCCV-BFD (Bidirectional Forwarding Detection)* * Complies with draft-ietf-pwe3-vccv

30 PW Solutions Advanced TS2007 Slide 30 Help!!!

31 PW Solutions Advanced TS2007 Slide 31 Fault Propagation Challenges: Alarms on the legacy services network should be propagated over the PSN transparently. Impairments on the PSN network should be forwarded to the legacy services network. Solution: Provide alarm forwarding mechanism between the native ATM/TDM network to the PSN and vise versa.

32 PW Solutions Advanced TS2007 Slide 32 TDM/ATM CE Trunk condition/ AIS PSN TDM/ATM PSN impairments (marked with ) can be: TDM-PW Packet loss,Jitter buffer underflow/overflows ATM-PW ETH Link down or BFD control message is not received As a result the PW GW 2 will generate alarms on the Attachment Circuit (AC): TDM PW: AIS/Trunk condition ATM PW: AIS OAM In addition PW GW 2 will signal the remote PW GW 1 on the local PSN fault PW-GW 2 PSN PW-GW 1 TDM/ATM CE

33 PW Solutions Advanced TS2007 Slide 33 TDM/ATM failure State Generate Failure Condition Report on local TDM/ATM Failure TDM/ATM to PSN The local PW-GW enters a forward defects state when one of the below are detected on the TDM/ATM network: LOS/ LOF/ AIS/ RDI The PW-GW 1 reports on local failure to the remote PW-GW 2 PW GW 2 propagate the relevant alarm on the Attachment Circuit TDM/ATM CE PW-GW 2 PSN PW-GW 1 TDM/ATM CE

34 PW Solutions Advanced TS2007 Slide 34

35 PW Solutions Advanced TS2007 Slide 35 Synchronization and Clock Distribution Challenge: PSN networks are by nature asynchronous with statistical behavior, thus, can not provide the clock source. Solution: Develop a mechanism which can recover synchronous clock over PSN networks. 3G RNC 2G BSC TDM ETH Packet Switched Network PSN-GW Radio Stations ATM TDM

36 PW Solutions Advanced TS2007 Slide 36 Synchronization and Clock Distribution Central unit distributes local clock source through the PSN Remote device recovers the clock and distributes to the radio stations Clock recovery performance Complies to G.823/4 Traffic interface & G.8261 Frequency Accuracy better than 16 ppb Hold over mechanism in case of clock stream failure Clock distributed over the PSN Node B BTS E1/T1 FE C.STM-1 ATM 2G BSC TDM E1/T1 Clock PSN-GW E1/T1 GbE 3G RNC Packet Switched Network

37 PW Solutions Advanced TS2007 Slide 37 thank you for your attention Merav Shenkar BroadBand Access team


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