Transcript PW Solutions advanced

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
PW-GW
PW-GW
ETH
ETH/IP/
MPLS
Network
PBX
ETH
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
PBX
PW-GW
ETH
Framing Sync
ETH/IP/
MPLS
Network
PW-GW
ETH
Framing Sync
PW Solutions Advanced TS2007 Slide 5
TDM PW Encapsulation Format
ETH (12)
ETH (12)
MPLS type
8847 (2)
IP type
0800 (2)
Tunnel
Label (4)
IP Header(20)
PW
label (4)
PW
label (4)
MPLS
I
P
TDM
CW
(4)
TDM/HDLC Payload
CRC
UDP
ETH (12)
•
ETH type
0800 (2)
IP Header (20)
UDP
Header (8)
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=mxN
•
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
ATMoPSN GW
ATM
ATMoPSN GW
n × E1 IMA/
STM-1
RNC
PSN
Node B
PW Solutions Advanced TS2007 Slide 8
ATMoPSN
ETH(12)
ETH(12)
IP
Type(2)
MPLS Tunnel
PW
Type(2) Label(4) Label (4)
IP
Header(20)
ATM*
CW (3)
PW
Label(4)
Cell
Header*
ATM* Cell
CW(3) Header*
ATM Payload
ATM Payload
CRC
(4)
CRC
(4)
• Overhead size:
• IP: 45 bytes
• MPLS: 29 bytes
*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
ATM
CW
Tunnel
Label
Cell
Header
PW
Label
ATM Payload
ATM
CW
Cell
Header
Cell
Header*
ATM Payload
ATM Payload
Cell
Header
CRC
ATM Payload
PW Solutions Advanced TS2007 Slide 10
Pseudowire Standards
Application
Standard
TDMoIP
IETF
Ietf-pwe3-tdmoip
IPmux-11
IPmux-14
IPmux-8/16
Gmux-2000
LA-110
Ietf-pwe3-cesopsn
ACE-3xxx
LA-110
LA-130
draft-ietf-pwe3-satop
ACE-3xxx
LA-110
LA-130
TDM PW
CESoPSN
SAToP
Product
ATMoPSN
ATM service transport
ietf-pwe3-atm-encap
ACE-3xxx
LA-110
LA-130
HDLCoPSN
HDLC transport
RFC 4618
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
Payload
PW Frame
Header
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
PW Frame
Overhead
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 mSec)
•
Detection of AAL5 SDU bit=1 triggers packet transmission
PW Solutions Advanced TS2007 Slide 21
TDMoIP Calculator
RAD Technical Support - Broadband Access Solutions
Best viewed at 1024x768 resulotion
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
Required TDMoIP BW:
2,624,171 [bps]
Required TDMoMPLS BW:
2,454,869 [bps]
Frames per second:
1,058 [fps]
Packetization Delay:
0.95 [ms]
E2E Delay (w/o network):
Max reordered packets
33.95 [ms]
Not supported [packets]
N/A
Error messages:
(Allowed range:2.5-200)
None
None
None
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
MPLS
TDM Payload size
VLAN
Disable
TDM Rate
640 kbps
Interface type
E1
Packetization Delay
500 usec
Line type
Framed
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
Preamble+Interframe Gap
Overhead Precentage
40
42.86%
Required Bandwidth [pps]
2000 pps
Required Bandwidth [kbps]
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
Disable
VLAN mode
1
46
94
48.9%
77.4%
Insert input ATM in CPS
ATM input in Kbits
PSN output in Kbits
Total bandwidth over ETH
Total bandwidth over GBE
1000
424.0
912.0
0.9%
0.1%
Insert number of peers
PSN output in Kbits
Total clock bandwidth over ETH
Total clock bandwidth over GBE
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
PW-GW
Wait 2 sec for an answer
and then stop transmission
* 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
Declares state=down
BFD
BFD
state = down
PW
PW
PSN
PW-GW
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
PW-GW 1
PW-GW 2
Trunk condition/
AIS
PSN
TDM/ATM CE
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
PW-GW 2
Generate Failure
Condition
PSN
TDM/ATM CE
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.
2G BSC
TDM
TDM
PSN-GW
PSN-GW
Radio
Stations
ETH
ATM
Packet
Switched
Network
ETH
3G RNC
ATM
PW Solutions Advanced TS2007 Slide 35
Synchronization and Clock
Distribution
Clock distributed
over the PSN
3G RNC
C.STM-1
ATM
E1/T1
PSN-GW
Node B
PSN-GW
FE
Packet
Switched
Network
GbE
Clock
2G BSC
E1/T1
TDM E1/T1
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