Migration to Next Generation SDH
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Transcript of Migration to Next Generation SDH
Presentation extracted from the book:“Migration to Next Generation SDH”
ISBN 84-609-4420-4see at wwww.trendcomms.com
Migration to Next Generation SDH
by José M. Caballero [email protected]
Section
SDH classic
3/58© 2005 Trend Communications - www.trendcomms.com
Reasons to define SDH
•••• The Antitrust law in the US followed by Bell being broken into smaller companies
•••• It was necessary to interconnect new PTTs: SONET definition
•••• B-ISDN specification to integrate any traf-fic: SDH and ATM standardisation
•••• Advanced management needs: comput-ers and telecom must work together
•••• Requirement for having new infrastruc-tures manage any type traffic: data, voice, multimedia
4/58© 2005 Trend Communications - www.trendcomms.com
bytes vs. bits
Standardised since 1988 when the G707, G708, G709 CCITT recommendations appeared
•••• SDH is byte oriented, it means that a byte is the unit for mapping and multiplexing
•••• STM-N is the name for the transport frames. They have always a period of 125µs
•••• An important consequence is that in SDH 1 byte represents a 64 Kbit/s channel
125 µs
0 n1 byte
rate =8 bits
125·10-6seg.= 64Kbit/s
0
125 µsframe 1 frame 2
5/58© 2005 Trend Communications - www.trendcomms.com
SDH is a flexible architecture •••• direct internet working between equipment
•••• scalability up to 10 Gbit/s
•••• direct add & drop for low speed tributaries
•••• Rich in OAM functions
•••• Support to fit any application
•••• remote and centralised management
•••• Fault tolerance: fast traffic routing in case of faults
•••• SDH is highly compatible with SONET
•••• very efficient in managing circuits
•••• fast circuit definition from a centralised point
•••• advanced facilities for quality monitoring
6/58© 2005 Trend Communications - www.trendcomms.com
Classic SDH: Circuit provisioning
SDH provides efficient, reliable and flexible transport for circuits
multiplexing, transport, routing, management, reliability
Internetservices Frame Relay ATM GSMPOTS
transport networkSDH
transmission media cable/fibre/radio
7/58© 2005 Trend Communications - www.trendcomms.com
Classic SDH Network elements
STM-NSTM-NREG
SDHMUX
STM-MSTM-N
STM-N
M >N
Regenerators Multiplexers
STM-M STM-M
STM-N, PDH
West East
Add & Drop Multiplexer (ADM) Digital Cross-Connect (DXC)
STM-N
STM-N
STM-N
STM-N
8/58© 2005 Trend Communications - www.trendcomms.com
Transport design
National Backbone
Primary Network
Access Network
STM-16
STM-4
STM-1 or PDH
9/58© 2005 Trend Communications - www.trendcomms.com
Nothing compares with SDH resilience
protection ringservice ring
ADM
ADM
AD
MADM
ADM
ADM
service &
ADM
ADM
AD
M
MUX
1:1
high priority
1:N
1+1MUX
MUXMUX
MUXMUX
protection rings
low priority
10/58© 2005 Trend Communications - www.trendcomms.com
The SDH multiplexing map
11/58© 2005 Trend Communications - www.trendcomms.com
The STM-1 frame
•••• STM-1 = AUG + RSOH + MSOH
•••• RSOH and MSOH sections allow the traffic management
•••• The VC4 is floating inside the STM-1: VC4 is asynchronous STM1 is synchronous
•••• The AU pointer always points to the position where the VC4 starts and follows possible fluc-tuations
RSOH
MSOH
AU4 ptr
1
VC4
27010
STM-1
HP POH
TU pointers
VCn VCn
LP POHLower Order Path Overhead
500 µs375 µs
250 µs125 µs
MUX
STM-1
3:1
STS-1STS-1STS-1
G1F2H4
J1B3C2
F3K3N1
ptr
V5
V5
ptr
K4N2
J2V5
9
1
270101 9
12/58© 2005 Trend Communications - www.trendcomms.com
OAM: Detected events at the end of a RS
LOS
LOF
MS-AIS (A1, A2 OK; the rest all 1s)
AU-AIS(All 1s)
TU-AIS(All 1s)
PDH AIS(All 1s)
B1 w ith errors
MS-RDI(K2=xxxxx110)
HO-RDI(G1=xxxx1xxx)
LO-RDI(V5=xxxxxxx1)
M U X REGLO-PTE HO-PTE
2M
34M
140M
STM-1 STM-NLO-PTEH O-PTE
2M
34M
140M
STM-1
HO-PTE LO-PTEM U X
MULTIPLEXER
SECTION
SECTION
HIGH ORDERPATH
LOW ORDERPATH
REGENERATORSECTION
REGENERATOR
Section
Next Generation SDH
NG SDH = classic SDH + [GFP+VCAT+LCAS]
14/58© 2005 Trend Communications - www.trendcomms.com
Streaming forces
New services and applications based on internet, mobile, multimedia, DVB, SAN, Ethernet or VPN, are demanding long hault transport. State of the art:
1. Ethernet, are in an early stage of development for efficient optical transport
2. Most have their transport infrastructure entirely based on SDH/SONET.
3. There is a lot of experience in managing SDH/SONET.
No other technology than SDH/SONET has this maturity grade at the optical physical layer.
TVVoIP
VPN
3G
InternetCircuit
xDSL
Mobile VPLSFRL VoD
ISDN
TVVoIP
VPN
3G
InternetTele
Circuit
Mobile MPLSFRL Gaming
ISDN
phone
VoIPTriplePlay
ISDNVoD
15/58© 2005 Trend Communications - www.trendcomms.com
Next Generation SDH: Packet Friendly
SDH/SONET has also evolved to more efficiently adapt statistical multiplexing traffic based on data packets.
TVVoIP
VPN
3G
Internet
SANCircuit
xDSL
Mobile VPLSFRL
VoD
ISDN
TV
Fibre ChannelESCON
LCAS
VoIP
VPN
3G
Internet
GFP-F
SDH/Sonet NG
PDH
Tele
WDM - Dark Fibre - Coax - Wireless - OTN
VLAN
Contiguous Concatenation Virtual Concatenation
MPLS
10/100/1000 Ethernet
FICON
DVB
GFP-T
SANCircuit
ATM
HDLC/PPP/LAPS
Mobile MPLSFRL
3play
ISDN
IPIP
Services
Transport Network
Transmission Media
phone
16/58© 2005 Trend Communications - www.trendcomms.com
Legacy and Next Generation SDH
The Next Generation of SDH/SONET is offering:•••• data-packet interfaces
•••• TDM interfaces
•••• new functionalities
The objective is:
•••• to support efficiently any type of traffic (including of data packets)
•••• get the best of Legacy SDH including:
- resiliency,
- reliability,
- scalability,
- centralised management
- rerouting
17/58© 2005 Trend Communications - www.trendcomms.com
Key NG SDH/SONET
GFP (Generic Framing Protocol)is robust and standardized encapsulation procedure for the transport of packetised data on SDH/SONET. In principal, GFP performs bit rate adaptation managing features such as priorities, discard eligibility, transport channels selection, and submultiplexing.
VCAT (Virtual Concatenation)is a mechanism which assigns granular bandwidth sizes rather than the exponential provision of the Contiguous Concatenation. Therefore VCAT is more flexible and efficient.
LCAS (Link Capacity Adjustment Scheme)LCAS can modify dynamically the allocated VCAT bandwidth by adding/removing members of a pipe in use. LCAS is being used also to implement diversity for traffic resilience.
LCAS
GFP-F NG SDH/SONET
Contiguous Concatenation Virtual Concatenation
GFP-T
18/58© 2005 Trend Communications - www.trendcomms.com
Next Gen. SDH Network elements
Legacy NE: Reg, Mux, ADM, DXC Multiservice Provisioning Platform (MSPP)
Multiservice Transport Platform (MSTP)
EthernetVPNDVBSAN
PDH
SDH
DWDM
Multiservice Switching Platform (MSSP)
SDHDWDMSDH
DWDMSDH
(classic ADM + packet interfaces)
(DXC-like)(MSPP + DWDM)
VPNDVBSAN
PDHEthernet
SDH
Client interfaces
SDH
19/58© 2005 Trend Communications - www.trendcomms.com
Multiservice Provisioning Platform (MSPP)
A Multiservice Provisioning Platform (MSPP) is basically the result of the evolution of legacy ADM and TDM interfaces and optical interfaces, to a type of access node that includes a set of:
•••• legacy TDM interfaces
•••• data interfaces, such as Ethernet, GigE, Fiber Channel, or DVB
•••• NG SDH/SONET functionalities such as GFP, VCAT and LCAS
•••• optical interfaces from STM-0/STS-1 to STM-64/OC-192
EthernetVPNDVBSAN
PDH
SDH
(classic ADM + packet interfaces)
20/58© 2005 Trend Communications - www.trendcomms.com
Multiservice Transport Platform (MSTP)
A Multiservice Transport Platform (MSTP) bassically is a MSPP with DWDM functions to drop selected wavelengths at a site that will provide higher aggregated capacity to multiplex and to transport client signals.
MSTP allows to integrate SDH/SONET, TDM and data services, with efficient WDM transport and wavelength switching.
Typically, MSTPs are installed in the metro core network.
DWDMSDH
(MSPP + DWDM)
VPNDVBSAN
PDHEthernet
21/58© 2005 Trend Communications - www.trendcomms.com
Multiservice Switching Platform
A Multiservice Switching Platform (MSSP) is the NG equivalent for cross-connect, performing efficient traffic grooming and switching at STM-N/OC-M levels but also at VC level.
MSSPs should support more than just data service mapping, namely true data services multiplexing and switching.
MSSP is still emerging as a NG Network element, while MSPP and MSTP are quite mature.
DWDMSDH
DWDMSDH
(DXC-like)
22/58© 2005 Trend Communications - www.trendcomms.com
Generic Framing Protocol (GFP)
•••• GFP, defined in ITU-T G.7041, provides data rate adaption and frame delineation
•••• There are two mapping service for data protocols:
1. GFP-T (Transparent) is a layer 1 encapsulation in constant sized frames. Optimised for traf-fic based on 8B/10B codification such as 1000BASE-T, Fibre Channel, and ESCON.
2. GFP-F (Framed) is a layer 2 encapsulation in variable sized frames. Optimised for data packet protocols such as DVD, PPP and Ethernet.
.
.
.
.
.
.
Ethernet SDH/Sonet Ethernet
GFP GFP
Source Sink
STM-n/OC-m
Encapsulating
T r a n s m i s s i o n
MappingMultiplexing Demultiplexing
DemappingDe-encapsulating
.
.
.
Tx
Port 1Port 2
Port n
.
.
.
Rx
Packets
Port 1Port 2
Port n
MSPP
queues demapper
MSPP
mapper Queues
23/58© 2005 Trend Communications - www.trendcomms.com
Frame-Mapped GFP (GFP-F)
•••• The entire client packet is dropped into a GFP frame
•••• Data Client signals such as Ethernet, PPP and DVB are queued waiting to be mapped
•••• Some codes can be removed to minimize the transmission size
•••• GFP-F supports submultiplexing onto a single channel for low-rate sources
GFP-F results in a more efficient transport, however, the encapsulation processes described above increase latency, making GFP-F inappropriate for time-sensitive protocols.
Sink
Source Sink
CIDSubmultiplexing
STM-n/OC-m
Encapsulation Mapping Multiplexing Demultiplexing Demapping Dencapsulation
......
RxPacketsqueues demappermapper
1 34
GFP
-F
GFP
-F
... ...
SA
N,
Fib
er
Ch
ann
el
SA
N,
Fib
er
Ch
an
ne
l
24/58© 2005 Trend Communications - www.trendcomms.com
Transparent GFP (GFP-T)
•••• GFP-T client signals are mapped into fixed-length GFP framesand transmitted immediately without waiting for the entire client data packet to be received.
•••• GFP-T encapsulates any protocol as long as they are based on 8B/10B line coding, which is why it is often called protocol-agnostic.
•••• ALL the client characters, without exception, are transported to the far end.
•••• GF-T is very good for isocronic protocols and SAN, such as ESCON or FICON. This is be-cause it is not necessary to process client frames or to wait for arrival of the complete frame
Source Sink
Encapsulation Mapping Multiplexing Demultiplexing Demapping Dencapsulation
Eth
ern
et, P
PP, D
VB
Eth
ern
et, P
PP, D
VB
...
demapper
STM-n/OC-m
8B/10B mapper
...
Reassembly
GFP
-T
GFP
-TIndependent Streams
......
25/58© 2005 Trend Communications - www.trendcomms.com
GFP mapping of client signals
Depending on the type of GFP in question, the mapping function can drop the whole signal (in the case of GFP-T), or can throw away certain delineation fields (GFP-F).
SoFDest Add
Source AddLength
LLC DataPadFCS
FlagAddressControlType
PayloadPadFCS
Extension
FlagPad
Preamble
Ethernet
HDSLC/PPPP
BBWSoF
HeaderDataCRCEOF
LLC/SNAP
Fiber Channel
Core Header
Payload Header
Extension Header
Payload
Check Sum
thrown awaytransported
GFP
GFP-F
GFP-F
GFP-F
26/58© 2005 Trend Communications - www.trendcomms.com
GFP frame formats and protocols
1
3
5
7
9
+1
+n+4
PTI
byte
PFI EXI typeUPI
PLI
cHEC (CRC-16)
tHEC (CRC-16)
EXI
eHEC (CRC-16)
pFCS (CRC-32)
Payload
+n
66
Core Header
Payload Header
Extention Header(optional)
Payload
Check Sum(optional)
GFP frame
PLI: PDU Length IndicatorcHEC: Core HEC protectionPTI: Payload type Identifier
000: client data100: client management
PFI: Payload FCS Indicator1: presence of FCS0: absence
EXI type: Extension Header Identifier0000: Null0001: Linear0010: Ring
UPI: User Payload Identifier (PTI=0)
Payload: Space for the framed PDUpFCS: Payload FCS
2
4
6
8
+2
01x: Ethernet (GFP-F)02x: PPP (GFP-F)03x: Fiber Channel (GFP-T)04x: FICON (GFP-T)05x: ESCON (GFP-T)06x: Gigabit Ethernet (GFP-T)08x: MAPOS (GFP-F)09x: DVB (GFP-T)0Ax: RPR (GFP-F)
0Cx: Async Fiber Channel (GFP-T)
scra
mbl
ed b
ytes
(opt
iona
l)
0Bx: Fiber Channel (GFP-F)
eHEC: Extension HEC protection
EXI: Extension Header Identifier
4 bytes
4 bytes
0-60 bytes
n bytes
0-4 bytes
tHEC: Type HEC protection
CIDSpare
Line
ar E
XI t
ype
Nul
l E
XI
tHEC: Type HEC protectionCID: Channel ID for submultiplex
tHEC
TypeType
tHEC
eHEC
27/58© 2005 Trend Communications - www.trendcomms.com
GFP-F vs. GFP-T
Feature GFP-F GFP-T
Protocol transparency low high
Efficiency high low
Isocronic protocols no yes
Encapsulation protocol level Layer 2 (Frames) Layer 1 (Physical)
Optimized for Ethernet SAN, DVB
LCAS protection likely poor
Statistical submultiplexing yes no
SAN transport no yes
Ethernet transport optimum possible
28/58© 2005 Trend Communications - www.trendcomms.com
Concatenation
Concatenation is the process of summing the bandwidth of X containers of the same type into a larger container.
There are two concatenation methods:
•••• Contiguous concatenation, which creates big containers that cannot split into smaller pieces during transmission. For this, each NE must have a concatenation functionality.
•••• Virtual concatenation, which transports the individual VCs and aggregates them at the end point of the transmission path. For this, concatenation functionality is only needed at the path termination equipment.
STM-1
STM-64
STM-16
STM-4
STM-256OC-768
OC-192
OC-48
OC-12
OC-3/STS-3VC-4
VC4-4c
VC4-16c
AU-4
AU4-4c
AU4-16c
STS-3c SPE
VC4-64c
VC4-256c
AU4-64c
AU4-256cAUG-256
STS-12c SPE
STS-48c SPE
STS-192c SPE
STS-768c SPE
STS-3c
STS-12c
STS-48c
STS-192c
STS-768c STS-768
AUG-64STS-192
AUG-16STS-48
AUG-4STS-12
AUG-1STS-3
x4
x4
x4
x4
40 Gbps
10 Gbps
2.5 Gbps
622 Mbps
155 Mbps
x1
x1
x1
x1
x1
x1
x1
x1
x1
x1
C-4-256c
C-4-64c
C-4-16c
C-4-4c
C-4
29/58© 2005 Trend Communications - www.trendcomms.com
Contiguous and Virtual Concatenation
G1F2H4
J1B3C2
F3K3N1
G1F2H4
J1B3C2
F3K3N1
Bandwidth requirement
G1F2H4
J1B3C2
F3K3N1
SDH
G1F2H4
J1B3C2
F3K3N1
G1F2H4
J1B3C2
F3K3N1
G1F2H4
J1B3C2
F3K3N1
G1F2H4
J1B3C2
F3K3N1
G1F2H4
J1B3C2
F3K3N1
VC4-4c VC4-3v or STS-9v
Bandwidth delivery
One Path Several paths
(430 Mbps)
21
3 III
4
II
IV
622 Mbps
3 x155 Mbps
Contiguous concatenation Virtual concatenation
(3 in SDH, or9 in SONET)
One VCG
3 VC members
30/58© 2005 Trend Communications - www.trendcomms.com
Contiguous Concatenation (VCAT)
Contiguous concatenation: Pointers and containers. A VC-4-Xc (X = 1, 4, 16, 64, 256) structure, where X represents the level. The increment/decrement unit (justification) is 3 X, as it depends on the level: AU-4=3 bytes, AU-4-256c=768 bytes.
VirtualContainer
VCtype
ContiguousConcatenation
Numberof VCs
G1F2H4
J1B3C2
F3K3N1
R
VC-4-Xc / STS-3Xc SPE
Fixed columns
261X
C-4-Xc
260X1
H1 Y Y H2 1 1 H3 H3 H3
H3
H1 Y Y....... H2 1 1....... H3 H3 H3.......
H2H1 1 3
1 9
1 36
3
12 24
H1 Y Y....... H2 1 1....... H3 H3 H3.......1 14448 96
AU-3 ptr
AU-4 ptr
AU-4-4c ptr
AU-4-16c ptr
H1 Y Y....... H2 1 1....... H3 H3 H3.......1 9X3X 6X
AU-4-Xc ptr
6
Y: 1001SS11
1: All 1s byte Justification unit = 3 X bytes size = X-1
(STM-0/STS-1)
(STM-1/OC-3)
(STM-4/OC-12)
(STM-16/OC-48)
(STM-n/OC-m)
STM / STS pointers
or SPE
31/58© 2005 Trend Communications - www.trendcomms.com
Virtual Concatenation (VCAT)
Packet-oriented, statistically multiplexed technologies, such as IP or Ethernet, do not match well the bandwidth granularity provided by contiguous concatenation.
•••• VCAT is an inverse multiplexing technique that allows granular increments of bandwidth in single VC-n units.
•••• At the source node VCAT creates a continuous payload equivalent to X times the VC-n
•••• The set of X containers is known as a Virtual Container Group (VCG), and each individual VC is a member of the VCG.
•••• Lower-Order Virtual Concatenation (LO-VCAT) uses X times VC11, VC12, or VC2 contain-ers (VC11/12/2-Xv, X = 1... 64).
•••• Higher-Order Virtual Concatenation (HO-VCAT) uses X times VC3 or VC4 containers (VC3/4-Xv, X = 1... 256), providing a payload capacity of X times 48 384 or 149 760 kbit/s.
VirtualContainer
VCtype
VirtualConcatenation
Numberof VCs
32/58© 2005 Trend Communications - www.trendcomms.com
Virtual Concatenation Operation
•••• MFI: Multiframe Indicator, VCG: Virtual Container group, SEQ: Sequence Number
•••• Virtual concatenation is required only at edge nodes
•••• Sink node must compensate for the different delays
VC3-4vVC3-4v
A B
FE
X YG
50%
25%VC3-4vVC3-4v
MFI=k+1
MFI=k
SQ=0..3
MFI=i
MFI=i-1
MFI=iSQ=0..3 t1
t1-125µst0+125µs
t0
Rate Adaption,VC3
555
555
Source Sink node
VC GroupContiguous PayloadsVC3 with SEQ=2 and SEQ=3
SDH/SONET
Delay adjust
VC Group Contiguous Payloads
SEQ=0
25%
MSSP
VC3
VC3
#0
VC3
#2
VC3#3
VC3#3
VC3#1
VC3#1
ReassemblyMapping, Segmentation
VC3#2
VC3#0
MSSP
33/58© 2005 Trend Communications - www.trendcomms.com
Virtual Concatenation Graphically
G1
J1B3C2
1
G1F2H4
J1B3C2
F3K3N1
VC-3
871
VC-3G1F2H4
J1B3C2
F3K3N1
125 µs
AU3 ptrsRSOH
MSOH
MFI=0
STM-n
SEQ=0...X
9
11 n·270
AU3 ptrsRSOH
MSOH
MFI=1
STM-n
SEQ=0...X
2·n·270
AU3 ptrsRSOH
MSOH
MFI=2
STM-n
SEQ=0...X
3·n·270
AU3 ptrsRSOH
MSOH
MFI=4095
STM-n
SEQ=0...X
4096·n·270
375 µs 512 ms MFI=0
STM-n. . .
VC-3G1F2H4
J1B3C2
F3K3N1
SEQ=0MFI=0
SEQ=1
SEQ=3MFI=0.
..
9
1
VC3-4v
4·841
X -Segments
X times VC3
VC-3
SEQ=3MFI=1.
..
9
1
VC3-4v
87
4·841
X -Segments
X times VC3
G1F2
J1B3C2
SEQ=0
VC-3
MFI=4095
SEQ=1
SEQ=3MFI=4095.
..
9
1
VC3-4v
871
4·841
X -Segments
X times VC3
. . . . . .
. . . . . .
(VC-3-Xv)
t
. . .
.
. . .
.
. . .
.
. . .
.
. . .
.
. . .
.
t
SEQ=0...X
EOS EOS EOS
Con
tiguo
us p
aylo
ad
VCGSEQ=0MFI=1
SEQ=1F2H4
VC-3G1F2H4
J1B3C2
F3K3N1
VC-3G1F2H4
J1B3C2
F3K3N1
VC-3G1F2H4
J1B3C2
F3K3N1
VC-3G1F2H4
J1B3C2
F3K3N1
34/58© 2005 Trend Communications - www.trendcomms.com
Virtual vs. Contiguous Concatenation
SDH SONET X times Capacity Justification Transport
VC-4 STS3c-SPE 1 149,760 Kbps 3 bytes STM-1/OC-3
VC-4-4c STS12c-SPE 4 599,040 Kbps 12 bytes STM-4/OC-12
VC-4-16c STS48c-SPE 16 2,396,160 Kbps 48 bytes STM-16/OC-48
VC-4-64c STS192c-SPE 64 9,584,640 Kbps 192 bytes STM-64/OC-192
VC-4-256c STS768c-SPE 256 38,338,560 Kbps 768 bytes STM-256/OC-768
SDH SONET X times Capacity Virtual Capacity
VC-11-Xv VT.15-Xv 1 to 64 1,600 Kbps 1,600 to 102,400 Kbps
VC-12-Xv VT2-Xv 1 to 64 2,176 Kbps 2,176 to 139,264 Kbps
VC-2-Xv VT6-Xv 1 to 64 6,784 Kbps 6,784 to 434,176 Kbps
VC-3-Xv STS-1-Xv 1 to 256 48,384 Kbps 48,384 to 12,386 Kbps
VC-4-Xv STS-3c-Xv 1 to 256 149,760 Kbps 149,760 to 38,338,560 Kbps
35/58© 2005 Trend Communications - www.trendcomms.com
Virtual vs. Contiguous Concatenation
Service Bit Rate Contiguous Concat. Virtual Concatenation
Ethernet 10 Mbit/s VC-3 (20%) VC-11-7v (89%)
Fast Ethernet 100 Mbit/s VC-4 (67%) VC-3-2v (99%)
Gigabit Ethernet 1000 Mbit/s VC-4-16c (42%) VC-4-7v (95%)
Fiber Channel 1700 Mbit/s VC-4-16c (42%) VC-4-12v (90%)
ATM 25 Mbit/s VC-3 (50%) VC-11-16c (98%)
DVB 270 Mbit/s VC-4-4c (37%) VC-3-6v (93%)
ESCON 160 Mbit/s VC-4-4c (26%) VC-3-4v (83%)
36/58© 2005 Trend Communications - www.trendcomms.com
K4 multiframe (VCAT & LCAS codification)
•••• K4 is part of the LO-PO overhead and is repeated every 500 ms
•••• 32 bits are sent in a complete multiframe which takes 16ms to repeat. (500 x 32=16 ms)
•••• The bit-2 superframe is made up of 32 multiframes and takes 512 ms to repeat.
K4 multiframe
MFI: Multiframe Count Indicator [0...31] SQ: Sequence Indicator int he VCG [0...
1 2 4 6 8 10 12 143 5 7 9 11 13 15 16frame
0 16ms
CTR
L
17 18 20 22 24 26 28 3019 21 23 25 27 29 31 32
RS-
Ack
V5Lower Order Path Overhead
125 µs250 µs
375 µs500 µs
(1bit per .5ms)K4 bit2
bit2
0000
100
010
0010
0
0011
0
0100
0
0101
0
0110
0
0111
0
0001
1
0010
1
0011
1
0100
1
0101
1
0110
1
0111
1
0000
0
1 2 4 6 8 10 12 143 5 7 9 11 13 15 16k4 superframe
MFI
512ms
1000
110
010
1010
0
1011
0
1100
0
1101
0
1110
0
1111
0
1001
1
1010
1
1011
1
1100
1
1101
1
1110
1
1111
1
1000
0
17 18 20 22 8 26 28 3019 21 23 25 27 29 31 32
0
SQCTRL...
CRC-3
J2 N2K4
MFI CTRLSQ MST CRC-30 0 0 0
37/58© 2005 Trend Communications - www.trendcomms.com
H4 multiframe (VCAT & LCAS codification)
•••• H4 is part of the HO-PO overhead
•••• H4 is repeated every 125 ms
•••• 16-byte multiframes takes 16 ms
•••• A complete multiframe of 4096 bytes takes 512 ms to repeat (125x4096=512 ms)
0001
0010
0100
0110
1000
1010
1100
1110
0011
0101
0111
1001
1011
1101
1111
0000
0001
0010 4
1110
0011
1111
0000
1 2 256
0011
CTR
L
0 0
0 0
CR
C8
MST
0 0
0 RSA
ck
0 0
0 0
SQ
0 0
0 G
ID
0 0
0 0
0 0
0 0
0 0
0 0
MFI
1
CTR
L
MFI
2
0 0
0 G
ID
SQ
0 0
0 0
1 2 4 6 8 10 12 143 5 7 9 11 13 15 16 409617 18 19 20 21
5-8bits
1-4bits
frame
MFI1
0ms 2ms 512mstime
G1F2H4
J1B3C2
F3K3N1
multiframe multiframe
Hig
er O
rder
Pat
h O
verh
ead
MFI2: Multiframe indicator part 2 [0...255] MFI: Combination of MFI2-MFI1 [0...4095]MFI1: Multiframe indicator part 1 [0...255]
SQ: Sequence Indicator int he VCG [0...255]
38/58© 2005 Trend Communications - www.trendcomms.com
Ethernet service provided by VCAT/LCAS
The link between node A and node Z transports Ethernet frames using a Virtual Concatenation Group of three members. Three separate LCAS protocols constantly monitor each peer connection: LCAS-a of node R talks with LCAS-a of node Z, LCAS-b(R) with LCAS-b(Z), ... LCAS-n (R) with LCAS-n (Z)
GFP
Ethernet
Ethernet frame
VCAT
Traffic
LCAS
S T
W
X
Payload Segregation
TrafficControlAdaption
MSSP - A
Ethernet
NG SDH
Legacy SDH MSSP - BAccess Access
Payload Aggregation
Flow Control
LCAS
VCAT member
Node RNode Z
Flow Control
Ethernet service
Y
R Z
CP1
CP2
ab
c-d
ab
c-d
39/58© 2005 Trend Communications - www.trendcomms.com
Link Capacity Adjustment Scheme (LCAS)ITU-T as G.7042, designed to manage the bandwidth allocation of a VCAT path. LCAS can add and remove members of a VCG that control a VCAT channel. LCAS cannot adapt the size of the VCAT channel according to the traffic pattern.
Source to Sink messages:
•••• Multi-Frame Indicator (MFI) keeps the multiframe sequence.
•••• Sequence Indicator (SQ) indicates member’s sequence to reassemble correctly the client signal that was split and sent through several paths.
•••• Control (CTRL) protocol messages which can be fixed, add, norm, eos, idle, and dnu.
•••• Group Identification (GID) is a constant value for all members of a VCG.
Sink to Source include:
•••• Member Status (MST), which indicates to source each member status: fail or OK.
•••• Re-Sequence Acknowledge (RS-Ack) is an ack of renumbering after a new eos member.
40/58© 2005 Trend Communications - www.trendcomms.com
LCAS protocol
fixed: Indicates fixed bandwidth and no LCAS supportadd: Member to be added to the VCGnorm: Normal transmissioneos: End of sequence, the member has the highest VCG seq number, Normal transmissionidle: Member is part of the VCG or to be removeddnu: Do Not Use, receive side reported MST FAIL status
ack: Re-Sequence Acknoledge after eos msg (RS-Ack msg)
ok: active member, no failure condition detected (MST msg)fail: failure condition detected in member (MST msg)
Source to Sink(CNTRL message)
Sink to Source(MST & RS messages)
Sinkfixed, add, norm, eos, idle, dnu
ok, fail, ackSource So Sk
41/58© 2005 Trend Communications - www.trendcomms.com
Simplified LCAS Source and Sink State Machine
Start
MADD
MREMOVE
IDLE
ADD NORM
REMOVE
DNU
add
norm, eos, ack
failok
ack, fail idle
idle
ok
idle
MREMOVE
dnu
OK
IDLE
FAIL
eos, norm,
MADD
fail
ok, dnu, ack
Startfail
others
MREMOVE
idle, fixed, fail
add
fail
Source
IDLE: Not provisioned memberADD: In process of being added to the VCGNORM: Active and provisioned member, good pathDNU (Do Not Use): Provisioned but its path has failedREMOVE: In process of being removed of the VCG
Sink
IDLE: Not provisioned memberOK: Provisioned and active memberFAIL: Provisioned member, failed path
Source States Sink States
states in transition
dnu, idle
So Sk
MADD, MADD,MREMOVEMREMOVE
MADD: add one or more members of the VCGMREMOVE: remove one member of the VCG
42/58© 2005 Trend Communications - www.trendcomms.com
VCAT Channel managed with LCAS
LCAS helps network operators to efficiently control NG SDH connections established at VCAT sites. The use of LCAS is not compulsory, but improves VCAT management
Sink
Source
LCAS
LCAS
VCGTx Rx
Source
TxRx
Sink
VCAT channel
LCAS
LCAS
Node A
fixed, add, norm, eos, idle, dnuok, fail, ack
IDLE IDLEADD FAIL
NORM OKDNU FAIL
REMOVE OK
abcd
hijk
fixed, add, norm, eos, idle, dnuok, fail, ack
MADDMREMOVE
Node B
NMS
MADD
MREMOVE NMS
MADDMREMOVE
NMS
MADDMREMOVE
NMS
NMS: Network Management System
SinkSource
Member States
43/58© 2005 Trend Communications - www.trendcomms.com
LCAS protocol: MADD and Path error
a b c d a b c d
IDLE IDLEADD FAIL
NORM OKDNU FAIL
REMOVE OK
add (b)
ack
eos (b)norm (d)
fail (b)
ok
dnu (b)eos (d)
ack
ok (b)eos (b)
norm (d)
MADD (b)
ack
MADD (b)
SinkSource
LCAS sample
.
.
.path error in (b)
no error
Member States
Sink Member StatesSource Member States
44/58© 2005 Trend Communications - www.trendcomms.com
LCAS protocol: MREMOVE
LCAS is a two-way handshake protocol resident in H4 and K4 and executed permanently between source and sink as many times as VCAT members.
IDLE IDLEADD FAIL
NORM OKDNU FAIL
REMOVE OK
SinkSource
LCAS sample
Member States
MREMOVE (d)
idle (d)fail (d)
idle (b)fail (b)
eos (a)
.
.
.
ack
MREMOVE (b)
a b c d a b c dSink Member StatesSource Member States
45/58© 2005 Trend Communications - www.trendcomms.com
Sink messages are fault tolerant
Sink to Source messages (MST, RS-Ack) are redundant while Source to Sink are specific to each member. This means that Sink messages are repeated as many times as members in the group. It also means that the origin of sink messages is irrelevant, because all the members are sending the same information in a multiframe.
1a2a
3a
1b2b
3b
1a2a
3a
1b2b
3b
Source-A
Sink-B
Sink-A
Source-B
LCAS
Si-A to So-A messages
So-B to Si-B Ctrl. messages
Si-B to So-B messages
So-A to Si-A Ctrl. messages
Rx
Tx
VCG
Rx
Tx
46/58© 2005 Trend Communications - www.trendcomms.com
H4 multiframe sequence
0255
160159 9596
128 127192191
22422331
32
40953072
0MFI 63
642048
1024
bytes
H4
16 bytes
multiframe (225)
2 ms
0 21 3member
8 9
4 65 7
255
.....
status (0-7)
021
3
64ms
256 -
MST MST
member MST status32 multi frames
8 9CTRL 0 CRC8 MST RSA 0 SQ
GID 0
00
MFI
1
8 9
16MFI
512ms
4096 bytes
256 multiframes
ok / fail
225
multiframe (31)
multiframe (0)
member status
ok / fail
ok / fail
ok / fail
ok / failok / failok / fail
ok / fail
MSTMST
MST MST
MSTMST
255.....
02 13
MSTMST
2 ms
47/58© 2005 Trend Communications - www.trendcomms.com
LCAS applications
•••• VCAT bandwidth allocation, LCAS enables the resizing of the VCAT pipe in use when it receives an order from the NMS to increase or decrease the size.
•••• Network Resilience, In the case of a partial failure of one path, LCAS reconfigures the con-nection using the members still up and able to continue carrying traffic.
•••• Asymmetric Configurations, LCAS is a unidirectional protocol allowing the provision of asymmetric bandwidth between two MSSP nodes to configure asymmetric links
•••• Cross-Domain Operation, because LCAS resides only at edge nodes it is not necessary to coordinate more than one configuration centre
Path1 = 25%
Path3 = 50%
A B
FE
X YG
A B
FE
X YG
Path1= 35%
Path3 = 65%
Normal operation After breakdown
VCATVCAT VCAT VCAT
LCASLCASMSSPMSSP
Path225%
Path20%
Section
Conclusions
49/58© 2005 Trend Communications - www.trendcomms.com
SDH is future proof
•••• SDH cannot be considered anymore as a “legacy technology”
•••• The evolution to Next Generation SDH is the future
•••• Future proof at least for the next 10 years
•••• NG SDH can deliver packet and TDM services
•••• Carriers are already migration from static, circuit-oriented SDH tomultiservice packet-friendly NG SDH
50/58© 2005 Trend Communications - www.trendcomms.com
Migration to Next Generation
It is only necessary to migrate the edges to get a full Next Generation SDH network
IT IS TODAY’S BEST COMBINATION FOR DATA AND CIRCUIT TRANSPORT
SDHLCASVCAT Virtual Containers Transport
Bandwidth management
Paths, Sections
GFC Mapping in Frames
Laye
rs
SDH SDH SDHLCASVCATGFC
Paths, Sections
EthernetVPNDVBSAN
PDHEthernetVPNDVBSAN
PDHMSSP MSSP
Existing SDH/Sonet
Next Generation SDH
Clients Clients
SDH NGSDH classic
51/58© 2005 Trend Communications - www.trendcomms.com
NG SDH means unification and standardisation
Next Generation SDH unifies and standardises transport infrastructure for any type of client network packet or circuit oriented network such as Ethernet, PDH, Frame Relay, UMTS, SAN...
ATM
Telephone
UMTS
SDH
SDH
SDHnode
Frame Relay
STM-NGFrame Relay
MSSP
52/58© 2005 Trend Communications - www.trendcomms.com
Old and New services as well
•••• NG SDH helps to provide the right SLA to Ethernet services
•••• Transport for high definition audio and video
•••• High speed data for Internet or other networks
•••• Fast bandwidth management to satisfy requirements
•••• Integration under the same architecture circuit and packet networks
ServicesTelephony
Frame RelayUMTS
GSM
InfrastructuresSDH DWDM
Ethernet
ATM access
FrameRelay
IWU
Host
Superserver
SAN
Wireless
VoIP
53/58© 2005 Trend Communications - www.trendcomms.com
Cost effective
•••• Universal standard: multivendor
•••• Unifies infrastructures under a central architecture avoiding a new overlap network
•••• Reduces the number of network elements needed to provide advanced services
•••• New technologies are making NG SDH more competitive and cheaper
•••• With just a few network elements is possible to configure a network
•••• Simplifies the management because of centralised configurations
Next Gen SDH network
SDH accessSDH ring2,5 Gbit/s
Ethernet access
Data storagePDH access
54/58© 2005 Trend Communications - www.trendcomms.com
Telecom basis in the next 10 years?
•••• “SDH will be the dominant technology in the next 10 years” Pioneers Optical Edge Net-works Boston (MA) June 2000
•••• “SDH is being used in wireless, we think there is a market at least for the next 10 years” Eli Lotan Global Telephony March 01
•••• “Ethernet demand lights up but SDH will remain at the core network” Ken Weiland Tele-communications International April 03
•••• “Ethernet and Optic networks have to match SDH resilience and management to chal-lenge SDH at the metro and core network” JM Caballero Mundo Electr. April 04
•••• “Installed base is huge to simply walk away from” S. Clavena Heaving Reading Nov. 03
•••• “Ethernet, of course, but over SDH” Network Planning and Operations US
55/58© 2005 Trend Communications - www.trendcomms.com
Ethernet challenge or SDH complement?
•••• Just a few carriers and operators around the world are setting up Core Networks removing SDH and relying only on Ethernet and/or DWDM
•••• It has always been difficult to justify in economic, technical and management terms a com-pletely new separate network. And that is still the case.
•••• Ethernet reduces leased access costs while NG SDH enhances QoS
•••• Native Ethernet services, and best effort technologies in general, do not scale well
•••• SDH resilience is critical to deliver 24/365 Ethernet services
•••• Ethernet is by nature a best effort technology, carrier-class is already under way
•••• Ethernet does not match today the OEM functions provided by SDH
•••• A pure packet network, i.e. Ethernet + MPLS, has to emulate circuits: it’s a risky solution!
56/58© 2005 Trend Communications - www.trendcomms.com
All-optical challenge or SDH complement?
•••• DWDM alone does not have the diversity or management functions of NG SDH
•••• The new MSTP nodes combines reconfigurable OADM with NG SDH features
•••• Provides new interfaces (packet + circuit oriented) while offering wider managing services
•••• Automate wavelength provisioning and lower wavelength delivery costs
•••• Ability to reduce network elements in the circuit path
Conclusion: Optical layer integration is a must for NG SDH using MSPP that will provide higher flexibility and Lower Capital Expense (Capex) operational expense (Opex)
57/58© 2005 Trend Communications - www.trendcomms.com
New data services
CPE Access Metro Core
Physical
Transport
Service
ClientGigE, Circuit, ATM
FRL, SAN, DVB
MSPP
MSTP
MSSP
ROADM
ADM
CXC
58/58© 2005 Trend Communications - www.trendcomms.com
NG SDH is S·T·R·A·T·E·G·I·C•••• Is being adopted not only by incumbent operators and carriers but also by new ones.
•••• It is interesting to consider the adoption of RPR and/or MPLS to enhance the feature of the Ethernet + NG SDH tandem to layer 2 protection, QoS and multipoint access.
•••• Video transport and Storage over NG SDH is just starting to impact in today’s networking
•••• Automatic layer 1 reconfiguration complements Layer 2 RPR reconfiguration
•••• High reliability equivalent similar in core and metro
•••• Centralised management of events, bandwidth provisioning
•••• Next Generation network (such as MSPP, MSSP) elements will be as fundamental to tele-com networks in the coming decade as routers were to the Internet of the 90s