RAD International Technical Seminar

Pseudowires Solutions – Advanced

Presented by:

Merav Shenkar

E-mail: [email protected]

Tel-Aviv, May 2007

Agenda

• • •

Introduction PW protocols for different services The PW Challenges

• • PSN QoS Throughput & Delay • • PW OAM- connectivity confirmation Fault propagation • Clock

PW Solutions Advanced TS2007 Slide 2

PW Solutions Advanced TS2007 Slide 3

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 PBX PBX

PW-GW

ETH

ETH/IP/ MPLS Network

ETH

PW-GW PW Solutions Advanced TS2007 Slide 4

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

PBX Framing Sync PW-GW

ETH

ETH/IP/ MPLS Network

ETH

PW-GW Framing Sync PBX PW Solutions Advanced TS2007 Slide 5

TDM PW Encapsulation Format

ETH (12) MPLS type 8847 (2) Tunnel Label (4) PW label (4) ETH (12) IP type 0800 (2) IP Header(20) PW label (4) MPLS I P TDM CW (4) UDP ETH (12) ETH type 0800 (2) IP Header (20) UDP Header (8) TDM/HDLC Payload CRC

• Overhead size: • • • IP: 46 bytes MPLS: 30 bytes UDP: 50 bytes *HDLC encapsulation is done according to IP/MPLS: RFC 4618

PW Solutions Advanced TS2007 Slide 6

TDMoIP Payload Size

ETH IP UDP CW TDM/HDLC Payload CRC

• • • TDMoIP Unframed/Framed payload size: is between 48-1440 bytes nx48 bytes (where n=1,2,3,……,30)

CESoPSN & SAToP payload size:

is between 32-512 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)

PW Solutions Advanced TS2007 Slide 7

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

Node B

ATM

ATMoPSN GW Node B PSN ATMoPSN GW

n × E1 IMA/ STM-1

RNC PW Solutions Advanced TS2007 Slide 8

ATMoPSN

ETH(12) MPLS Type(2) Tunnel Label(4) PW Label (4) ATM* CW (3) Cell Header* ATM Payload CRC (4) ETH(12) IP Type(2) IP Header(20)

•

Overhead size:

• IP: 45 bytes • MPLS: 29 bytes

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)

PW Solutions Advanced TS2007 Slide 9

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 CRC ATM CW Cell Header ATM Payload Cell Header ATM Payload Cell Header ATM Payload PW Solutions Advanced TS2007 Slide 10

Pseudowire Standards

Application

TDM PW ATMoPSN HDLCoPSN

Standard

TDMoIP CESoPSN SAToP ATM service transport HDLC transport

IETF Ietf-pwe3-tdmoip Ietf-pwe3-cesopsn

draft-ietf-pwe3-satop

ietf-pwe3-atm-encap RFC 4618 Product

IPmux-11 IPmux-14 IPmux-8/16 Gmux-2000 LA-110 ACE-3xxx LA-110 LA-130 ACE-3xxx LA-110 LA-130 ACE-3xxx LA-110 LA-130 LA-110

PW Solutions Advanced TS2007 Slide 11

PW Solutions Advanced TS2007 Slide 12

PW Solutions Advanced TS2007 Slide 13

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 GW

VCC VCC E1 UBR CBR

PSN PW Solutions Advanced TS2007 Slide 14

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

PW Solutions Advanced TS2007 Slide 15

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

PW Solutions Advanced TS2007 Slide 16

PW Solutions Advanced TS2007 Slide 17

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

PW Solutions Advanced TS2007 Slide 18

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.

Header Header Payload PW Frame Header PW Frame Payload Payload PW Frame PW Solutions Advanced TS2007 Slide 19

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

Overhead Payload Overhead PW Frame Payload PW Frame PW Solutions Advanced TS2007 Slide 20

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 – 5000000 m Sec) • Detection of AAL5 SDU bit=1 triggers packet transmission

PW Solutions Advanced TS2007 Slide 21

TDMoIP Calculator

RAD Technical Support - Broadband Access Solutions

TDMoIP/MPLS Calculator

Product: IPmux-14 Interface: E1 Line Type: Fractional CAS Disabled Number of Time-Slots in the bundle: 31 TDM Byte/Frame size: 5x48 TDMoIP Version: II Ethernet utilization: Full VLAN Tagging: No Jitter Buffer size [ms]: 32 2 .

5 200 ) Required TDMoIP BW: Frames per second: Packetization Delay: E 2 E Delay (w/o network): Max reordered packets N/A Error messages: None None None Best viewed at 1024 x 768 resulotion 2 , 624 , 171 [bps] 2 , 454 , 869 [bps] 1 , 058 [fps] 0 .

95 [ms] 33 .

95 [ms] Not supported [packets] Visit our eSupport system at:www.rad.com/techsup.htm

PW Solutions Advanced TS2007 Slide 23

CESoPSN & SAToP Calculator

TDMoPSN Calculator (Ver 1.2) PSN Type VLAN Interface type Line type Number of Time Slots (N) Multiplier (M) Jitter Buffer Delay(usec) Ethernet Utilization

MPLS Disable E1 Framed 10

[1-31]

4 2000

[4-51] [500-32000]

Preamble+Interframe Gap

TDM Payload size TDM Rate Packetization Delay Actual Jitter Delay End-to-End Delay Total Overhead Total Frame Length Overhead Precentage Required Bandwidth [pps] Required Bandwidth [kbps]

40 640 kbps 500 usec 2000 usec 2500 usec 30 70 42 .

86 % 2000 pps 1440 kbps

PW Solutions Advanced TS2007 Slide 24

ATMoPSN Calculator

PSN Type

IP

Insert number of concatenated cells Total overhead Total frame length Overhead compare to total frame length Overload in percentage Insert input ATM in CPS ATM input in Kbits PSN output in Kbits Total bandwidth over ETH Total bandwidth over GBE Insert number of peers PSN output in Kbits Total clock bandwidth over ETH Total clock bandwidth over GBE VLAN mode

Disable

1

46 94 48 .

9 % 77 .

4 %

1000

424 .

0 912 .

0 0 .

9 % 0 .

1 %

1

114 .

4 0 .

1 % 0 .

0 %

Type

VC

Instructions:

1 . Select the desired PSN type (MPLS/IP), the VLAN mode (Disable/Enable) , and the Connection type (VP/VC) 2 . Enter the number of cells which will be concatenated into a single frame; the total overhead, total frame length and overload in percentage fields are updated accordingly.

3 . Enter the input ATM stream in CPS (Cells per second); the total bandwidth over ETH/GBE fields are updated accordingly. 4 . Enter the number of peers towards which clock stream is distributed; the total clock bandwidth over ETH/GBE fields are updated accordingly.

Note

:Calculation for PSN output in Kbits include the preamble and inter frame gap.

PW Solutions Advanced TS2007 Slide 25

PW Solutions Advanced TS2007 Slide 26

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

PW Solutions Advanced TS2007 Slide 27

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 Wait 10 sec

Failure

5 OAM messages PW

PSN PW-GW

Wait 2 sec for an answer and then stop transmission

PW-GW

* TDMoIP OAM – RAD’s proprietary Operation Administration and Maintenance protocol

PW Solutions Advanced TS2007 Slide 28

ATM PWs

• • 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)* Declares state= down

BFD PW-GW PSN BFD

state = down Declares state=down

PW-GW

* Complies with draft-ietf-pwe3-vccv

PW Solutions Advanced TS2007 Slide 29

Help!!!

PW Solutions Advanced TS2007 Slide 30

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.

PW Solutions Advanced TS2007 Slide 31

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

TDM/ATM CE PW-GW 1 PSN PW-GW 2 Trunk condition/ AIS TDM/ATM CE PW Solutions Advanced TS2007 Slide 32

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

Report on local TDM/ATM Failure TDM/ATM failure State PW-GW 1 TDM/ATM CE PSN PW-GW 2 Generate Failure Condition TDM/ATM CE PW Solutions Advanced TS2007 Slide 33

PW Solutions Advanced TS2007 Slide 34

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.

Radio Stations

TDM

PSN-GW

ETH

Packet Switched Network

ETH

PSN-GW

TDM

2G BSC 3G RNC

ATM ATM

PW Solutions Advanced TS2007 Slide 35

Synchronization and Clock Distribution

Node B

E1/T1 E1/T1

PSN-GW

FE

Packet Switched Network Clock distributed over the PSN

C.STM-1 ATM

3G RNC PSN-GW

GbE

2G BSC

TDM E1/T1

Clock BTS

• • • 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

PW Solutions Advanced TS2007 Slide 36

thank you

for your attention

Merav Shenkar

BroadBand Access team Email: [email protected]

www.rad.com

PW Solutions Advanced TS2007 Slide 37