The Cisco® enhanced wavelength-division multiplexing (EWDM) product line allows users to scale the speed and capacity of the services offered in a coarse wavelength-division multiplexing (CWDM) network by offering the ability to insert up to 8 dense wavelength-division multiplexing (DWDM) wavelengths to the existing 8-wavelength CWDM channel plan.
Product Overview
The Cisco EWDM product line provides the ability to overlay up to 8 DWDM wavelengths with the 8 CWDM channels (1470, 1490, 1510, 1530, 1550, 1570, 1590, and 1610 nm). The principle is very simple, yet it is a unique approach in that the 8 DWDM wavelengths are inserted in between CWDM channels. EWDM allows 5 DWDM channels to be multiplexed between the 1530-nm and 1550-nm CWDM wavelengths and 3 DWDM channels between the 1550-nm and 1570-nm CWDM wavelengths. A total of 8 CWDM plus 8 DWDM wavelengths can be supported on the same fiber infrastructure. (See Figure 1)
Figure 1. Cisco EWDM Concept
The Cisco EWDM product line is composed of three passive units and an optical amplifier designed for EWDM applications (Figure 2). The three passive units support 8 DWDM channels (EWDM-MUX8=), 4 DWDM channels (EWDM-OADM-4=), and 2 DWDM channels (EWDM-OADM-2=), giving customers the flexibility to add 8, 4, or 2 DWDM channels to a CWDM network.
The channel plan for the EWDM channels is depicted in Figure 3. Since CWDM passive series filters tolerate for a drift of as much as +/-6 nm around the CWDM center wavelength, the 8 DWDM channels are selected such that they do not interfere with the CWDM spectral range.
Figure 2. EWDM Passive Units Front Panel
Figure 3. Cisco EWDM Channel Plan
The optical amplifier (EWDM-OA=) is an Erbium Doped Fiber Amplifier (EDFA) designed to boost 10-Gbps wavelengths enough to compensate for their lower power budget compared to CWDM 1/2-Gbps transceivers. Cisco EWDM is designed with the goal to support 10-Gbps upgrades of CWDM networks, and the optical amplifier enables users to deploy 10-Gbps DWDM optics along with lower speed signals without sacrificing the total network reach. Note that the optical amplifier works in conjunction with the passive units to boost the power of only the DWDM wavelengths. (See Figure 4.)
Figure 4. EWDM Optical Amplifier
Each EWDM component is compatible with the CWDM-CHASSIS-2=, the metal enclosure used for all other Cisco CWDM products.
Benefits of Cisco EWDM
The approach of Cisco EWDM at mixing CWDM and DWDM signals as well as the introduction of a custom designed amplifier yields the following benefits to end users:
• EWDM is built from the start with 10 Gbps in mind: customers can use DWDM technology to scale the speed of the services supported in a CWDM network.
• Customers can grow existing CWDM infrastructures to 16 total wavelengths. Adding DWDM channels does not sacrifice any of the 8 CWDM wavelengths.
• While upgrading to 10 Gbps, customers do not have to sacrifice the reach of their networks because of the reduced performance of 10-Gbps optics. The optical amplifier, designed for plug-and-play operations, will boost the power of 10-Gbps channels to match to total power budget available on CWDM lower speed services.
Applications
EWDM can be used to retrofit or expand a CWDM network with 10 Gigabit Ethernet capabilities while protecting 100 percent of the investment in the CWDM infrastructure. The EWDM components in the sample point-to-point configuration in Figure 5 are designed to interoperate transparently with the existing CWDM infrastructure to scale the total number of wavelengths to 16, with potentially up to 8 10 Gigabit Ethernet channels.
Figure 5. Example Deployment Scenario (West-to-East Direction Only Shown)
Figure 5 shows a configuration with 8 CWDM and 8 DWDM channels. Going west to east, this is how an EWDM configuration is deployed:
1. The CWDM "NETWORK TX" port, carrying the 8 CWDM wavelengths, is connected to the "CWDM-UPG RX" port of the EWDM unit. (The CWDM wavelengths are now ready to be multiplexed together with the DWDM wavelengths.)
2. At the same time, the EWDM passive device receives from its DWDM client ports the signals from 10 Gigabit Ethernet transceivers, multiplexes them together, and routes them out of the "AMP OUT" port.
a. If the overall loss experienced by the 10 Gigabit Ethernet wavelengths can be accommodated within the power budget of the 10 Gigabit Ethernet DWDM transceiver (for example, a DWDM Xenpak has 20 dB of power budget after ~80 km, taking into account dispersion penalties), simply use the single-mode simplex LC patch cord provided with the EWDM device to connect the "AMP OUT" to the "AMP IN." This way the DWDM wavelengths are fed back into the EWDM device ready to be multiplexed together with the CWDM signals.
b. If the 10 Gigabit Ethernet channels require extra power to match the power budget of the CWDM GBIC/SFP devices, then the DWDM wavelengths out of the "AMP OUT" port have to be injected into the "IN" port of the EWDM-OA=. The "OUT" port of the amplifier then feeds back the amplified signals into the "AMP IN" port of the EWDM passive device. This way the DWDM wavelengths are fed back into the EWDM device ready to be multiplexed together with the CWDM signals.
3. At this stage the EWDM unit performs the multiplexing operation of CWDM and DWDM wavelengths. The aggregate CWDM plus DWDM signal is then sent out of the EWDM "NETWORK TX" port connected to the "metro" fiber.
4. At the receiving end, the "metro" fiber is connected to the EWDM "NETWORK RX" port, which receives all the CWDM and DWDM wavelengths. The DWDM wavelengths are demultiplexed and routed to the client "TX" ports connected to the 10 Gigabit Ethernet transceivers (hosted in a Cisco Catalyst® line card, for example). The CWDM wavelengths pass through the EWDM device transparently and are directed out of the "CWDM-UPG TX" port.
5. The "CWDM-UPG TX" port is connected to the "NETWORK RX" port of the CWDM units in Figure 5. The CWDM device demultiplexes the CWDM wavelengths and directs them to the receivers of the CWDM transceivers (hosted in a Cisco Catalyst or MDS line card, for example).
EWDM Passive Unit Product Specifications
Figure 6 shows the EWDM passive unit front panel layout.
Figure 6. EWDM Passive Unit Front Panel Layout
Table 1 shows the EWDM-MUX8 passive unit optical specifications.
Table 1. EWDM-MUX8 Passive Unit Optical Specifications
Parameter
Path
Min
Max
Unit
Operating Band
1460-1620
Nm
Channel Spacing
100
GHz
DWDM Channel 0.5 dB Bandwidth
-0.12
+0.12
Nm
DWDM Channel
1 to 8
Insertion Loss
Mux DWDM (channel)
3.5
dB
Demux DWDM (channel)
2.5
Mux CWDM (band)
1
Demux CWDM (band)
1.5
Combined Mux Demux DWDM (same channel)
4.7
Isolation
Pass Port Isolation (In band Isolation)
15 mux
dB
Adjacent channels Isolation (DWDM Channels over DWDM or CWDM channels)
30 demux
Return Loss
45
dB
Directivity
50
dB
PDL
All Paths
0.2
dB
PMD
All Paths
0.2
ps
Optical Loss Uniformity
1.5
dB
Max Optical Input Power
300
mW
Table 2 shows the EWDM-OADM4 passive unit optical specifications.
Table 2. EWDM-OADM4 Passive Unit Optical Specifications
Parameter
Path
Min
Max
Unit
Operating Band
1460-1620
Nm
Channel Spacing
100
GHz
DWDM Channel 0.5 dB Bandwidth
-0.12
+0.12
nm
DWDM Channel
2,3,4,5
Insertion Loss
Mux DWDM (channel)
3.5
dB
Demux DWDM (channel)
2.5
Mux CWDM (band)
1
Demux CWDM (band)
1.5
Combined Mux Demux DWDM (same channel)
4.7
Isolation
Pass Port Isolation
(In band Isolation)
15 mux
30 demux
dB
Adjacent channels Isolation (DWDM Channels over DWDM or CWDM channels)
30
Return Loss
45
dB
Directivity
50
dB
PDL
All Paths
0.2
dB
PMD
All Paths
0.2
ps
Optical Loss Uniformity
1
dB
Max Optical Input Power
300
mW
Table 3 shows the EWDM-OADM2 passive unit optical specifications.
Table 3. EWDM-OADM2 Passive Unit Optical Specifications
Parameter
Path
Min
Max
Unit
Operating Band
1460-1620
Nm
Channel Spacing
100
GHz
DWDM Channel 0.5 dB Bandwidth
-0.12
+0.12
nm
DWDM Channel
7 and 8
Insertion Loss
Mux DWDM (channel)
2
dB
Demux DWDM (channel)
2
Mux CWDM (band)
1
Demux CWDM (band)
1
Combined Mux Demux DWDM (same channel)
3.1
Isolation
Pass Port Isolation
(In band Isolation)
15 mux
30 demux
dB
Adjacent channels Isolation (DWDM Channels over DWDM or CWDM channels)
30
Return Loss
45
dB
Directivity
50
dB
PDL
All Paths
0.2
dB
PMD
All Paths
0.2
ps
Optical Loss Uniformity
1
dB
Max Optical Input Power
300
mW
Table 4 shows a summary of the total add/drop loss suffered per channel with the EWDM passive units
1If the link is terminated with another EWDM-MUX8= device. If a different EWDM device terminates the link, the "DWDM ADD" insertion loss is 3.5 dB, and the "DWDM DROP" insertion loss is 2.5 dB.
2If the link is terminated with another EWDM-OADM4= device. If a different EWDM device terminates the link, the "DWDM ADD" insertion loss is 2.5 dB, and the "DWDM DROP" insertion loss is 2.5 dB.
3If the link is terminated with another EWDM-OADM2= device. If a different EWDM device terminates the link, the "DWDM ADD" insertion loss is 2 dB, and the "DWDM DROP" insertion loss is 2 dB.
Table 5 shows the EWDM passive unit environmental conditions.
Table 5. EWDM Passive Unit Environmental Conditions
Parameter
Min/Max Value
Operating Temperature
-5 ~ 55ºC
Storage Temperature
-40 to 85ºC
Operating Humidity
5 to 95%RH
EWDM Optical Amplifier Unit Product Specifications
Figure 7 illustrates the EWDM amplifier front panel layout.
Figure 7. EWDM Amplifier Front Panel Layout
The front panel includes:
• 3 LEDs to report the status of the device (Table 6)
• A hardware reset button (next to the alarm LED) (Table 7)
• An RS-232 interface with RJ45 connector (Table 8)
• The optical input and output ports based on LC connectors (Table 9)
Table 6. EWDM Front Panel LED State
Functionality
Possible State
Comment
Power
Ok
Green
Starting up
Green
Failure
Red
Input power alarm
In range
Green
Out of range
Red
Alarm LED
Normal condition
Green
Minor problem
Orange
Severe problem
Red
Table 7. EWDM Amplifier Unit Optical Specifications
