Tag Archives: DWDM ring

How to Light a DWDM Ring Beyond 10G?

Network layout nowadays is no longer limited by old rules created for early Ethernet networks. The technology and infrastructure devices available currently allows for different network topologies, including bus, star, ring and mesh networks. Each of them has its benefits and drawbacks and can be combined to suit application needs. This article emphasizes on the DWDM ring network configuration, illustrating the approaches to build a fiber ring beyond 10G.

What Is a DWDM Fiber Ring?

A fiber ring refers to the network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node. A ring configuration is designed to withstand a single failure. If there happens to be a failure, the system automatically reconfigure itself.

Similarly, a DWDM ring network includes a fiber in a ring configuration that fully interconnects nodes. Two fiber rings are even presented in some systems for network protection. This ring DWDM topology is commonly adopted in a local or a metropolitan area which can span a few tens of kilometers. Many wavelength channels and nodes may be involved in DWDM ring system. One of the nodes in the ring is a hub station where all wavelengths are sourced, terminated, and managed, connectivity with other networks takes place at this hub station. Each node and the hub have optical add-drop multiplexers (OADM) to drop off and add one or more designated wavelength channels. As the number of OADMs increases, signal loss occurs and optical amplifier is needed.

DWDM ring

How to Create a DWDM Fiber Ring Beyond 10G?

Assuming to build a higher than 10G optical ring using two strands of dark fibers, all nodes in this ring configuration are less than 10km apart and there are 8 nodes in total. Here we illustrate the options for achieving a DWDM ring beyond 10G.

20G Fiber Ring

For a 20G ring, the configuration is rather simple. There is no need for an OADM or Mux/Demux, it is recommend to use an Ethernet switch with two SFP+ ports and a pair of BIDI SFP+ optics.

Items Description
S5800-48F4S High Performance Data Center Switch (48*1GE+4*10GE)
10GBASE-BX SFP+ Generic Compatible 10GBASE-BX SFP+ 1270nm-TX/1330nm-RX 10km DOM Transceiver
10GBASE-BX SFP+ Generic Compatible 10GBASE-BX SFP+ 1330nm-TX/ 1270nm-RX 10km DOM Transceiver
40G Fiber Ring

There are three options for creating a 40G DWDM ring.

1. Use a switch with QSFP+ ports, and using QSFP+ optics in accordance. This can be the most cost-effective option for 40G if you have no future plan for more than 40G on the ring.

Items Description
S5850-48S6Q High Performance Data Center Switch (48*10GE+6*40GE)
40GBASE-LR4 Generic Compatible 40GBASE-LR4 and OTU3 QSFP+ 1310nm 10km LC Transceiver for SMF

2. Use four 10G SFP+ optics and a CWDM OADM. You could even scale up to 18 channels giving you a 180G ring if you were use all 18 CWDM channels and had that large of a OADM or Mux/Demux. First four channels with lower cost SFP+ optics, wavelength 1270nm through 1310nm. Then the next 14 channels 1350nm to 1610nm adopts SFP+ with relatively higher cost. You would need a SFP+ port per channel on both ends, and a passive CWDM OADM.

Items Description
CWDM OADM Single Fiber/ Dual Fiber CWDM OADM, East and West
10GBASE-LR SFP+ Generic Compatible 10GBASE-LR SFP+ 1310nm 10km DOM Transceiver
10GBASE-ER SFP+ Generic Compatible 10GBASE-ER SFP+ 1550nm 40km DOM Transceiver

3. Use 10G DWDM SFP+ optics and a DWDM OADM. You can choose less expensive 100Ghz optics that have up to 40 or 44 channels, or the expensive 50Ghz optics that can reach up to 80 or 88 channels.

Items Description
DWDM OADM Single Fiber/ Dual Fiber DWDM OADM, East and West
10G DWDM SFP+ Generic C40 Compatible 10G DWDM SFP+ 100GHz 1545.32nm 40km DOM Transceiver
10G DWDM SFP+ Generic H50 Compatible 10G DWDM SFP+ 50GHz 1537nm 40km DOM Transceiver
100G Fiber Ring

As for a 100G fiber ring, you can count on Ethernet switches that have 100G QSFP28 uplink ports, along with 100G QSFP28 optics. This would allow a 100G connection each way around the ring.

Items Description
S5850-48S2Q4C Carrier Grade 100G-uplink Switch (48*10GE + 2*40GE + 4*100GE)
100GBASE-LR4 Generic Compatible QSFP28 100GBASE-LR4 1310nm 10km Transceiver
Conclusion

Fiber ring enables more reliability and survivability: if a single link failure should occur – the traffic can simply be sent the other way around the ring. With the pervasiveness of Ethernet technology, the ring architecture is widely adopted to construct a Metropolitan Area Network (MAN), Metro-Ethernet service and school district that uses municipal fiber pathways. Several options for creating fiber ring beyond 10G are presented, along with the optical components needed. Hope this could be informative enough.