Principles of Circuit Switched Networks · The DWDM terminal at Washington reports the SONET...
Transcript of Principles of Circuit Switched Networks · The DWDM terminal at Washington reports the SONET...
Principles of Circuit Switched Networks
John S Graham Indiana University
Syllabus
• Review of Current OpAcal Technologies – What’s a circuit; what’s a cross‐connect? – How are SONET/SDH and OTN different? – How are packet and circuit switching merging?
• Principles of OA&M in OpAcal Networks – Why’s my router interface reporAng only B3 errors? – Abandon BFD All Ye Who Enter Here!
• DiagnosAc Tools in OpAcal Networks – The Joy of Loops – TAPs
Hybrid Packet/OpAcal Networks IP
Ethernet HDLC
10 G LAN PHY 10 G WAN PHY 1 G PHY
SONET [OC192]
Op=cal Transport Network [OTU2]
GFP (G.7041)
packet
op=cal
DWDM
What is a Circuit? 1/2
A circuit connects two endpoints by means of a series of alterna=ng fibers and cross‐connects
Terminal Terminal Regenerators
Tributary Interface
Line Interface
What is a Circuit? 2/2
Tributary Interface
Line Interface
ADM Connected in a Ring
Synchronous = Flexible MulAplexing
OC‐48 Line (South West)
OC‐48 Line (North East) OC‐48 Line (West North)
OC‐48 Line (East South)
S
E
N
W
OpAcal Transport Network (OTN)
OpAcal Data Unit (ODU‐k)
Client
OpAcal Payload Unit (OPU‐k)
OpAcal Transport Unit (OTU‐k)
OPU1 ODU1 OTU1
OTU3
OTU2 OPU2 ODU2
OPU3 ODU3
OPU0 ODU0
2.5G
1G
10G
40G
× 4
× 2
× 4
× 16
SONET/SDH versus OTN
SONET/SDH
1. Timing 1. Internally synchronous
2. Not synchronous with clients
2. Flexible mulAplexing
3. Fixed frame rate
4. Can be very bandwidth efficient
5. No error correcAon
OTN (G.709) 1. Timing
1. Internally asynchronous 2. Synchronous with clients
2. Enforced mulAplexing scheme
3. Fixed frame size 4. Possibility of bandwidth
inefficiencies 5. Coding gains from forward
error correcAon
Of Frames and Payloads
• Ethernet or HDLC – Frame consists of indivisible overhead, payload and checksum
• SONET/SDH – Frame consists of overhead and a container – Payload is a separate structure with its own overhead – Payload overlaps two successive frames – Pointers required to adapt payload received from an alien SONET line
• OTN – Has characterisAcs of both the above
Single Payload FloaAng Within SPE
What Does A Cross‐Connect Represent?
• SONET – Transfer payload (with overhead) between SONET lines
• OTN – Moves an ODU‐j between different OTU‐k (k >= j)
• For 3R operaAon on a concatenated ODU‐k • For switching ODU‐j within channelized ODU‐k
– OCh cross‐connect moves an OTU‐k frame from one ITU wavelength to another
• Packet‐OpAcal – Switching VLAN tags at the packet/opAcal interface
Packet OpAcal Convergence
• OpAcal provides to packet: – Economies of scale and mulAplexing – Tried and true OA&M
• IP rouAng concepts from packet switching: – End‐to‐end automated provisioning – Replace inflexible SONET and WDM rings with mesh architectures
– ProtecAon based on available instead of reserved bandwidth
– Traffic classificaAon
GFP: The Great Arbitrator
Adapted from: IEEE CommunicaCons Magazine, May 2002
Tasks Performed by GFP
• Major – Client frame delineaAon
– Client payload mapping – Client‐to‐carrier rate adaptaAon
• Minor – Limited OA&M (Link Loss Forwarding)
– OpAonal client frame mulAplexing
(Undesirable) AlternaAves to GFP
• ATM – Cell overhead causes 10% bandwidth inflaAon – AdaptaAon funcAons needlessly complex
• Packet over SONET (POS) – Byte stuffing causes non‐determinisAc bandwidth inflaAon
– Expensive router hardware
16
SONET Layers
SecAon Layer SecAon Layer
R1 ADM2 DXC ADM1
Path Layer ConnecAon
Line Layer Line Layer
SecAon Layer SecAon Layer
R2
17
Bit Interleaved Parity (BIP) 1 0 0 0 1 1 0 1
1 1 1 0 0 1 1 0
0 0 1 1 1 1 0 1
0 1 0 1 1 0 1 0
1 0 1 1 0 1 0 1
1 0 1 1 1 0 0 1
1 0 1 1 1 0 0 1
1 0 0 0 1 1 0 1
0 0 1 1 1 1 0 1
0 1 0 1 1 0 1 0
1 0 1 1 0 1 0 1
1
1 0 0 1 1 0
0 1 0 1 1 1 0 0 1
1 1 1 1 1 0 0 1
Sent Calc
=
≠
18
Error ReporAng: SecAon
unidirec=onal errors from right to le\
ADM2 R1 DXC ADM1 R2
B1
B1 B1
B1
19
Error ReporAng: Line
unidirec=onal errors from right to le\
R1 DXC ADM1 R2 ADM2
B2
B2
M0
20
Error ReporAng: Path
unidirec=onal errors from right to le\
R1 DXC ADM1 R2 ADM2
B3 G1
21
Summary of Node Status
Node Section Line Path
NE FE NE FE
ADM1 0 0 0
R1
R2 0
DXC 0 0
ADM2 0 0 0 0
22
PM ClassificaAons
• CV = code violaAon (parity error) • ES = any second in which there is at least one CV, LOF or LOS
• SES = any second in which K or more CV or an AIS‐L alarm are counted
• UAS‐L = 10 consecuAve SES‐L • FC‐L = number of failure events
23
Performance Categories
Signal State BER Action
Anomaly Normal ≤ 10-8 TCA
Degrade BER-SD 10-5 – 10-7 SNC/N Switch
Soft Failure BER-SF ≥ 10-4 SNC/I or
Mesh Switch
Hard Failure LOS, LOF, AIS-L
24
Alarms: UnidirecAonal Failure
ADM2 R1 R2
AIS‐L
RDI‐L
DXC ADM1
AIS‐P
RDI‐P
25
Alarms: BidirecAonal Failure
ADM2 R1 R2
AIS‐L
RDI‐L
DXC
AIS‐P
RDI‐P
AIS‐L
ADM1
RDI‐P
RDI‐L
OTN Provides OA&M to DWDM Systems: Ethernet Circuit
A. OADM at Birmingham reports Loss of Signal (LOS) B. Downstream transponder suppresses laser C. Upstream transponder suppresses laser; customer routers do not need to run BFD!
P2P Ethernet Circuit ConnecCng Customer Routers in Atlanta and Indianapolis
OTN Provides OA&M to DWDM Systems: SONET Circuit
A. OADM at Charlose reports Loss of Signal (LOS)
B. A SONET AIS‐L alarm is transmised towards the customer router at Washington
C. The customer router responds by transmitng a SONET RFI‐L alarm
D. The DWDM terminal at Washington reports the SONET AIS‐L alarm on its trib port E. The DWDM terminal at Atlanta reports the SONET RFI‐L alarm on its trib port
Forward & Backward Defect Indicators in OTN
• Loss of Signal alarm displayed at Birmingham
• The ten opAcal channels between Birmingham and Atlanta each support a BDI alarm
• The single cross‐connect at Birmingham between DLMs facing Atlanta and Nashville propagates an FDI alarm.
29
Payload Problems
1. Path not terminated 1. UNEQ 2. AIS‐P
2. Path trace mismatch (J1)
3. Loss of Pointer 4. Payload label mismatch (C2)
Infinera Port Loops 1/2
Atlanta New York
Terminal Loop at Atlanta
Atlanta New York
Facility Loop at Atlanta
Infinera Port Loops 2/2
Atlanta New York
Atlanta New York
Terminal Loop at Atlanta
Facility Loop at New York
CoreDirector Path‐Level Loops 1/2
1‐A‐3‐1:190‐192 1‐A‐6‐1:1‐3
1‐A‐2‐1:189‐191 1‐A‐7‐1:1‐3
ATLA
NEWY
Equipment loop on drop‐side GTP at ATLA
CoreDirector Path‐Level Loops 2/2
1‐A‐3‐1:190‐192 1‐A‐6‐1:1‐3
1‐A‐2‐1:189‐191 1‐A‐7‐1:1‐3
ATLA
NEWY
Facility loop on line‐side GTP at ATLA
Quiz Time!
1‐A‐3‐1:190‐192 1‐A‐6‐1:1‐3
1‐A‐2‐1:189‐191 1‐A‐7‐1:1‐3
ATLA
NEWY
1. Describe the loop applied at ATLA
2. What alarm(s) will be displayed at NEWY?
3. How many alarms will be displayed at NEWY?
4. Draw and describe the other loop that can be applied at ATLA to cause alarms at NEWY
Recommended Resources
Descrip=on Publisher hsp://preview.Anyurl.com/…
SONET Poster Agilent
yjtga6d
Next‐GeneraAon SONET Poster yas2p3p
OTN Poster Ciena
y8k2u3u
OpAcal Control Plane Poster yeug9ss
These colourful A1‐sized wall posters provide an excellent ready‐reference to the prevalent packet‐opCcal technologies.
36 With thanks to Steve Surek of Ciena CorporaAon for discussions regarding OTN