Along with the introduction of Arista 7500E series switches, this article will illustrate several 100G DWDM solutions for distance up to 80 km, 150 km and 3000 km as well.

1. WHITE PAPER
FS.COM White Paper | Several 100G DWDM Solutions for Arista 7500E Series
To keep up with the global demand for higher bandwidth, Arista has designated 7500E series switch
to address 100G long-hual dense wavelength division multiplexing (DWDM) connectivity. Arista
100G interconnect solution combines Layer 2/Layer 3 switching, wire-speed encryption and
coherent DWDM into a high-density line card for the Arista 7500E data centers. Along with the
introduction of Arista 7500E series switches, this article will illustrate several 100G DWDM solutions
for distance up to 80 km, 150 km and 3000 km as well.
Arista 7500E Series Switch & Line Card
Arista 7500E series is the second generation of 7500 series switch that delivers scalable and
deterministic network performance for mission critical data centers, enterprise and HPC
environments. Available in a compact 7RU (4-slot) or 11RU (8-slot), Arista 7500E offers over 30Tbps
of total capacity for 1,152 ports of 10GbE, 288 ports of 40GbE and support for 96-port 100GbE with
a broad choice of interface types that support flexible combinations of 10G, 40G and 100G modes
on a single port.
The 7504 and 7508 are the two types of Arista 7500E series switches. The 7508 systems support 8
linecards, dual supervisor modules and 6 fabric modules to provide a full 30Tbps of capacity. The
smaller 7504 systems share a common architecture with the 7508 with the primary difference
being support for 4 linecards and 15Tbps of forwarding capacity. The most unique feature of this
switch is that it can connect with 10G SFP+, 40G QSFP+, 100G QSFP28 and CFP2 modules.
Several 100G DWDM
Solutions for Arista
7500E Series

2. WHITE PAPER
FS.COM White Paper | Several 100G DWDM Solutions for Arista 7500E Series
Arista 7500E series line card for addressing 1/10G, 40G and 100G with full support for industry
standard connections and comprehensive layer 2 and 3 features for flexible deployment choice. The
line card delivers error-free performance up to 3000 km of fiber and consumes less than 140W per
100Gbps. Similar to any other Arista platform, the DWDM line card utilizes the single binary image
of Arista’s extensible operating system (EOS). Line cards with CFP2 and QSFP support standard
100G for both single and multimode fiber for distance up to 40 km.
Why Need 100G DWDM Solution?
100G optical transceivers provide the most straightforward method to connect 100G traffic over
long-hual applications. 100G optics like CFP and QSFP28 offer cost-optimized solutions for
connecting 100G switches together in a rack or data center. Nevertheless, the small and
cost-effective QSFP28 100G optics now can only handle connections over distances of less than 10
km. For example, QSFP28 LR4 is compliant with 100GBASE-LR4 standard that operates over duplex
LC cables for a link length of 10 km.
As to the CFP form factors, coherent CFP modules is designed to support metro and long-hual
DWDM applications. CFP 100GbASE-ER4 can support up to 40 km. However, owing to its large size
and high power consumption, CFP transceivers are less popular on the market. If you want to use
CFP optics for 100G deployment, keep in mind, CFP modules are too large to fit in the Ethernet
switches and will significantly reduce port counts and increase power usage, making 100G switches
poor performance in cost-effectiveness. Therefore, customers who want to upgrade 100G network
can only cover a distance of 10 km, which is obviously insufficient for geographically separated data
centers or metro infrastructures. Figure 2 shows the basics of DWDM system.

3. WHITE PAPER
FS.COM White Paper | Several 100G DWDM Solutions for Arista 7500E Series
To realize 100G long-distance transmission, Arista 100G DWDM solution combines DWDM optics
with a fully passive Mux/Demux system that can handle up to 3,000 km. Arista 100G DWDM
solution is a 6 x 100G Coherent DWDM line card for the 7500E series with integrated wire-speed
encryption and analog coherent CFP2 optical interfaces. Several use cases for the Arista 7500E
Series DWDM card in multi-site data center networks exist. The following sections identify three
use cases for Arista 7500E DWDM solutions.
Use Cases for Arista 7500E DWDM Solutions
 Use Case 1—Less Than 80KM Dark Fiber Connection
For a typical metro link that is less than 80 km, Arista 7500E Series DWDM line cards can directly
terminate a dark fiber connection providing a point-to-point connection between two locations.
Just as figure 3 shows, Arista DWDM solution is ideal for metro applications transmitting up to
9.6Tbps traffic without the need for any additional amplification.
 Use Case 2—Greater Than 80 km But Less Than 150 km
When extending the distance beyond 80 km, there is a need to amplify the signal to offset heavy
signal loss that occurred in the light signal when passing through fiber cables, patch panels and

4. WHITE PAPER
FS.COM White Paper | Several 100G DWDM Solutions for Arista 7500E Series
other optical devices. Under this circumstance, EDFA’s or Erbium Doped Fiber Attenuators are
employed to give the aggregated wave a boost.
By using EDFAs (seen in Figure 4) to the transmit side of each end of the dark fiber link, the signal
can be boosted to achieve distances of up to 150 km. Exact distances will be dependent on the
number of patches, fiber splices and quality of the fiber.
 Use Case 3—Greater Than 150 km But Less Than 3,000 km
Arista 7500E DWDM solutions can also cover the distance of greater than 150 km but less than
3000 km. Employing further EDFAs at a spacing of approximately 80 km along the fiber route allows
the length of a connection to be extended to over 3,000 km. As shown below, EDFAs are used on
both paths to boost the signal.
Supported Optics for Arista 7500E Series
All Arista 10G SFP+ transceivers, with the exception of LRM, are supported on the Arista 7500E SFP+
ports.

5. WHITE PAPER
FS.COM White Paper | Several 100G DWDM Solutions for Arista 7500E Series
Interface Type SFP+ ports
10GBASE-CR 0.5m-5m
10GBASE-AOC 3m-30m
10GBASE-SRL 100m (OM3) / 150m (OM4)
SFP-10G-SR 300m (OM3) /400m (OM4)
SFP-10G-LRL 1km
SFP-10G-LR 10km
SFP-10G-ER 40km
10GBASE-DWDM 80km
SFP-10G-ZR100 100km
100Mb TX, 1GbE SX/LX/TX Yes
The 40G QSFP+ transceivers and cables allow for 4x10G mode support with the use of fiber
breakout cables, MTP to LC cassettes, or QSFP to SFP+ cables. See the below table for details on the
latest supported 40G transceivers.
Interface Type QSFP+ ports
40GBASE-CR4 0.5m-5m
40GBASE-AOC 3m-100m
QSFP-40G-UNIV 150m (OM3) / 150m (OM4), 500m (SM)
QSFP-40G-SRBD 100m (OM3) /150m (OM4)
QSFP-40G-SR4 100m (OM3) / 150m (OM4)
QSFP-40G-XSR4 300m (OM3) / 400m (OM4)
QSFP-40G-PLRL4 1km (1km 4x10G LR/LRL)
QSFP-40G-PLR4 10km (10km 4x10G LR/LRL)
QSFP-40G-LRL4 1km
QSFP-40G-LR4 10km
QSFP-40G-ER4 40km

6. WHITE PAPER
FS.COM White Paper | Several 100G DWDM Solutions for Arista 7500E Series
100G QSFP28 and CFP2 Optics
Interface Type 100G CFP2 Ports 100G QSFP Ports
100GBASE-XSR10
300m OM3 / 400m OM4 Parallel
MMF
100GBASE-SR4
100m OM3 / 150m OM4 Parallel
MMF
100GBASE-LR4 10km SM Duplex 10km SM Duplex
100GBASE-LRL4 2km SM Duplex
100GBASE-ER4 40km SM Duplex
100GBASE-CWDM4 2km SM duplex
100GBASE-PSM4 500m SM Parallel
100GBASE-AOC 3m to 30m
100GBASE-CR4 1m to 3m
Conclusion
Arista 7500E DWDM solution works in conjunction with passive Optical Mux/Demux devices and
in-line amplifiers to support additional bandwidth and extended reaches. Arista 7500E DWDM
solution can directly reach up to 80 km without requiring in-line amplification, which is ideal for
metro applications. With an Optical Signal to Noise ratio (OSNR) of 11.6dB, it can be used
effectively for point to point long-haul applications up to 3,000kms with in-line amplifiers and
multiplexers.

7. WHITE PAPER
FS.COM White Paper | Several 100G DWDM Solutions for Arista 7500E Series
Contact Us
Manufacturing R & D (China)
Eastern Side, Second Floor, Science &
Technology Park, No.6, Keyuan Road,
Nanshan District, Shenzhen 518057,
China
Tel: +86 (755) 8300 3611
Fax: +86 (755) 8326 9395
Email: sales@fs.com
APAC Office (Hong Kong)
1220 Tung Chun Commercial Centre,
438-444 Shanghai Street, Kowloon,
HongKong
Tel: +(852) 817 636 06
Fax: +(852) 817 636 06
Email: sales@fs.com
North America (United States)
18625 72nd Ave S, Kent, WA 98032
United States
Tel: +1 (253) 277 3058
Fax: +1 (253) 246-7881
Email: sales@fs.com
London Office (United Kingdom)
Third Floor 207 Regent Street, London,
W1B 3HH, United Kingdom
Tel: +44 (020) 3287 6810
Notice: This document is for informational purposes only and does not set forth any warranty, expressed or
implied, concerning any equipment, equipment features, or service offered or to be offered by FS.COM.
FS.COM reserves the right to make changes to this document at any time, without notice, and assumes no
responsibility for its use. This information document describes features that may not be currently available.
Contact a FS.COM sales team for information on feature and product availability.
Follow us
LinkedIn
Twitter
Facebook
G+
Pinterest
Youtube
Blog