tel-aviv, may 2007 pseudowires solutions – advanced presented by: merav shenkar e-mail:...

RAD International Technical Seminar

Tel-Aviv,May 2007

Pseudowires Solutions – Advanced

Presented by:

Merav Shenkar

E-mail: [email protected]

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


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

ETHETH

PW-GWPW-GWPBX PBX

ETH/IP/ MPLS

Network


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

ETHETH

PW-GWPW-GWPBX

Framing Sync Framing Sync

PBX

ETH/IP/ MPLS

Network


ETH (12)ETH (12) ETH type

0800 (2)

ETH type0800 (2) IP Header (20)

IP Header (20) UDP Header (8)

UDP Header (8)

ETH (12)ETH (12) IP type

0800 (2)

IP type0800 (2) IP Header(20)

IP Header(20)

ETH (12)ETH (12) MPLS type

8847 (2)

MPLS type8847 (2) Tunnel

Label (4)

TunnelLabel (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)

PW label (4)

TDMCW (4)

TDMCW (4)

PW label (4)

PW label (4)

IP

MPLS

UDP

TDM/HDLC PayloadTDM/HDLC Payload CRC

CRC


TDMoIP Payload Size

• TDMoIP Unframed/Framed payload size: is between 48-1440 bytesnx48 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)

ETHETH

IPIP

UDPUDP

CWCW

TDM/HDLC PayloadTDM/HDLC Payload

CRCCRC


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 ATMoPSN GW

PSN

RNCn × E1 IMA/

STM-1

Node B

Node B

ATM


ATMoPSN

• Overhead size:

• IP: 45 bytes

• MPLS: 29 bytes

ETH(12)MPLS Type(2)

TunnelLabel(4)

PW Label (4)

ATM* CW (3)

Cell Header* ATM Payload CRC

(4)

ETH(12)IP

Type(2)IP

Header(20)PW

Label(4)ATM*

CW(3) CellHeader* 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)


Multiple Cells Concatenation Format

ATM Payload size

• Up to 29 cells in a single frame

• Cell concatenation reduces overhead

ETHMPLS Type

TunnelLabel

PW Label

ATM CW Cell

Header*

Cell Header*

ATM Payload

ATM CW

Cell Header

Cell Header ATM Payload Cell

Header

Cell Header ATM Payload Cell

Header

Cell Header ATM Payload

CRC


Pseudowire Standards

Application Standard IETF Product

TDM PW

TDMoIP Ietf-pwe3-tdmoip

IPmux-11IPmux-14IPmux-8/16Gmux-2000LA-110

CESoPSN Ietf-pwe3-cesopsnACE-3xxxLA-110LA-130

SAToP draft-ietf-pwe3-satopACE-3xxxLA-110LA-130

ATMoPSN ATM service transport ietf-pwe3-atm-encapACE-3xxxLA-110LA-130

HDLCoPSN HDLC transport RFC 4618 LA-110


E1

VCC

VCCCBR

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


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


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


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


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

PW Frame

PayloadPayload

HeaderHeader

HeaderHeader

PW Frame

PayloadPayload

HeaderHeader

Payload Payload


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

PW Frame

PayloadPayload

PayloadPayload

OverheadOverhead

OverheadOverhead


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 Sec)

• Detection of AAL5 SDU bit=1 triggers packet transmission


TDMoIP Calculator

RAD Technical Support - Broadband Access Solutions Best viewed at 1024x768 resulotion

Product:

Required TDMoIP BW: 2,624,171 [bps]

I nterface:

Required TDMoMPLS BW: 2,454,869 [bps]

Line Type:

Frames per second: 1,058 [fps]

Number of Time-Slots in the bundle:

Packetization Delay: 0.95 [ms]

TDM Byte/Frame size:

E2E Delay (w/o network): 33.95 [ms]

TDMoIP Version:

Max reordered packets Not supported [packets]

Ethernet utilization:

N/A

VLAN Tagging:

Error messages:

J itter Buffer size [ms]: (Allowed range:2.5-200)

None

Visit our eSupport system at:www.rad.com/ techsup.htm

TDMoIP/ MPLS Calculator

None

None

Fractional CAS Disabled

Full

No

II

IPmux- 14

E1

5x48

31

32


CESoPSN & SAToP Calculator

TDMoPSN Calculator (Ver 1.2)

PSN Type TDM Payload size 40

VLAN TDM Rate 640 kbps

Interface type Packetization Delay 500 usec

Line type Actual Jitter Delay 2000 usec

Number of Time Slots (N) 10 [1-31] End-to-End Delay 2500 usec

Multiplier (M) 4 [4-51] Total Overhead 30

Jitter Buffer Delay(usec) 2000 [500-32000] Total Frame Length 70

Ethernet Utilization Overhead Precentage 42.86%

Required Bandwidth [pps] 2000 pps

Required Bandwidth [kbps] 1440 kbps

Disable

MPLS

E1

Framed

Preamble+Interframe Gap


ATMoPSN Calculator

PSN Type VLAN mode Type

Insert number of concatenated cells 1Total overhead 46Total frame length 94Overhead compare to total frame length 48.9%Overload in percentage 77.4%

Insert input ATM in CPS 1000ATM input in Kbits 424.0PSN output in Kbits 912.0Total bandwidth over ETH 0.9%Total bandwidth over GBE 0.1%

Insert number of peers 1PSN output in Kbits 114.4Total clock bandwidth over ETH 0.1%Total clock bandwidth over GBE 0.0%

IP Disable 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.


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


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

PW

Wait 10 sec

5 OAM messages

Failure

PW-GW PW-GW

PSN

Wait 2 sec for an answer

and then stop transmission


PW

ATM PWs

PW

Declares state= down Declares state=down

state = down

BFD BFD

PW-GW 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


Help!!!

Help!!!


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.


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


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


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 BSCTDM

ETH ETHPacket

SwitchedNetwork

PSN-GWPSN-GW

RadioStations

ATMATM

TDM


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-1ATM

2G BSC

TDM E1/T1

Clock

PSN-GW

PSN-GW

E1/T1

GbE

3G RNC

Packet SwitchedNetwork


www.rad.com

thank youfor your attention

Merav ShenkarBroadBand Access teamEmail: [email protected]

tel-aviv, may 2007 pseudowires solutions – advanced presented by: merav shenkar e-mail:...

Documents

pw slide

pw types

delay slide

psn psn psn gw slide

pw frames payload size

pw type optional

pw overhead introduc

pw bandwidth utilization