What is DWDM Channel Spacing?

DWDM channel spacing governs system performance; 100 GHz is the most commonly used and reliable channel spacing. This spacing allows for several channel schemes without imposing limitations on available fiber amplifiers. However, channel spacing depends on the system's components. Channel spacing is the minimum frequency separation between two multiplexed signals. An inverse proportion of frequency versus wavelength of operation calls for different wavelengths to be introduced at each signal. The optical amplifiers bandwidth and receivers ability to identify two close wavelengths, sets the channel spacing.

Red and Blue Bands

The ITU approved DWDM band extends from 1528.77 nm to 1563.86 nm, and divides into the red band and the blue band.  The red band encompasses the longer wavelengths of 1546.12 nm and higher.  The blue band wavelengths fall below 1546.12 nm.  This division has a practical value because useful gain region of the lowest cast EDFAs corresponds to the red band wavelengths.  Thus, if a system only requires a limited number of DWDM wavelengths using the red band wavelength yields the lowest overall system cost.

All About Dense Wave Division Multiplexing (DWDM)

The Dense Wave Multiplexing DWDM channel or light wavelength matrix (please see chart below) has brought tremendous benefit to the metropolitan and long haul data transmission world. Bandwidth hungry applications are requiring more information over the same transport infrastructure with the explosive growth of the internet.  With CWDM and DWDM Optics, the carrying capacity of the physical medium (fiber)  is increased because  each  DWDM/CWDM channel is transmitted at a different frequency.  Many engineers refer to this as the ‘rainbow’ of light, where each channels represents a color of light available within or over the medium (fiber). DWDM also has the ability to amplify all the wavelengths at the same moment, without first having to convert them to electrical signals, as well as the ability to carry signals of different speeds and types simultaneously over the medium (fiber).  This is called protocol and bit rate independence. DWDM is a big winner in the Metropolitan backbone.  It is fast and flexible in the provisioning of protocol- and bit rate-transparent, data centric, protected services, and has the ability to offer new and higher speed services at less cost. The key requirements for DWDM systems in the Metropolitan area include:  Multi-protocol support, cost effectiveness, reliability and availability, openness (interfaces, network management, standard fiber types, electromagnetic compatibility, ease of installation and management, size and power consumption, and scalability. Overall, the technical advantages to DWDM (Bandwidth Aside) are: DYNAMIC PROVISIONING (Provides engineers the ability to provision in days, not months, because of its fast and simple connections), SCALABILITY (DWDM leverages the available dark fiber to  meet the demand for capacity on point to point links and existing SONET/SDH rings), and TRANSPARANCY (It can transparently support TDM and data formats such as Gigabit Ethernet, ATM, ESCON, and fiber channel wit open interfaces over a common physical layer. DWDM enables a large savings on regenerators (RPTR) and amplifier infrastructure compared to the typical SONET/SDH optical networks, greatly reducing up front infrastructure cost barriers.   Besides the lowered infrastructure cost benefit, the DWDM systems have simplified the of network capacity by problem in many ways. Dense Wavelength Division Multiplexing (DWDM) ITU Grid: C-Band, 100 GHz Spacing Channel Frequency Wavelength Channel Frequency Wavelength (#) (GHz) (nm) (#) (GHz) (nm) 1 190100 1577.03 37 193700 1547.72 2 190200 1576.20 38 193800 1546.92 3 190300 1575.37 39 193900 1546.12 4 190400 1574.54 40 194000 1545.32 5 190500 1573.71 41 194100 1544.53 6 190600 1572.89 42 194200 1543.73 7 190700 1572.06 43 194300 1542.94 8 190800 1571.24 44 194400 1542.14 9 190900 1570.42 45 194500 1541.35 10 191000 1569.59 46 194600 1540.56 11 191100 1568.11 47 194700 1539.77 12 191200 1567.95 48 194800 1538.98 13 191300 1567.13 49 194900 1538.19 14 191400 1566.31 50 195000 1537.40 15 191500 1565.50 51 195100 1536.61 16 191600 1564.68 52 195200 1535.82 17 191700 1563.86 53 195300 1535.04 18 191800 1563.05 54 195400 1534.25 19 191900 1562.23 55 195500 1533.47 20 192000 1561.42 56 195600 1532.68 21 192100 1560.61 57 195700 1531.90 22 192200 1559.79 58 195800 1531.12 23 192300 1558.98 59 195900 1530.33 24 192400 1558.17 60 196000 1529.55 25 192500 1557.36 61 196100 1528.77 26 192600 1556.56 62 196200 1527.99 27 192700 1555.75 63 196300 1527.22 28 192800 1554.94 64 196400 1526.44 29 192900 1554.13 65 196500 1525.66 30 193000 1553.33 66 196600 1524.89 31 193100 1552.52 67 196700 1524.11 32 193200 1551.72 68 196800 1523.34 33 193300 1550.92 69 196900 1522.56 34 193400 1550.12 70 197000 1521.79 35 193500 1549.32 71 197100 1521.02 36 193600 1548.52 72 197200 1520.25 Note: for 200GHz spacing use either odd or even numbered channels.

New Price Reductions

We have just reduced pricing on some of our most popular Juniper parts:

EX-SFP-10GE-SR is now only $244.99
EX-SFP-10GE-LR is now only $465
EX-SFP-10GE-LRM is now only $475
EX-SFP-10GE-ER is now only $1049.99
EX-SFP-10GE-ZR is now only $2699.99

Click on the links to check them out!

You can also find our optics on Buy.com and Amazon.

Shipping

Lately, we have been getting a lot of questions about international shipping so we've decided to post some of the answers right here.  Read on to find out just how easy it is to get quality optical transceivers either shipped directly to you or drop shipped to a location of your choice.
We at Approved Networks, Inc. take pride in our highly flexible logistics capability.  Drop shipping to international and multi-site locations is a daily occurrence at our facility.  Our shipments test and ship the same day the order is received, unless the order is received past 3pm Pacific, but we will most certainly try to get it out if that’s needed.  Larger shipments of 1000+ optics can sometimes take a day or so to test and ship, but nevertheless, we do pride ourselves in the ability to ship product faster than anyone in our industry.  Typically the optics are at your site waiting for the switches/routers to be delivered.  Besides your typical clear channel 1000base through 100G receivers, we pride ourselves on the ability to quick-ship channel specific DWDM and CWDM product.  The channel just can’t compete with our ability to direct support and price colored optics.

The international shipping capability of our on-line check out process makes drop shipping to most world locations easy. Any VAT or tariff pricing, along with the chosen shipping charge according to your delivery needs, is added and the summation price is typically well below the in-country OEM cost for the same optics by the OEM.  We not only save the largest domestic end users in the world by drop-shipping to multiple locations, but we also support non-U.S. Headquartered companies directly.

Approved leverages every major shipping company (Fed Ex, UPS, DHL, and others) in order to calculate the best price for our customers. Although we always send a tracking number to the recipient when product is shipped, many of our customers prefer that we use their shipper number so that everything is reported on their internal shipping ledger.  Approved has shipped to the most remote areas of Africa, Asia, and Latin America, bringing ‘light’ to the most rural areas and the largest companies in the world.

Approved Networks Inc. takes pride in its ability to ship and track multiple orders.  Please let us know if you have any questions regarding our logistics.   Call:  800.590.9535

Testing

Each optical transceiver has unique EEProm attributes resident on the transceiver’s NVRAM. The OEM’s IOS looks for these attributes in order to enable “plug and play” functionality - so no error codes occur and there is no command line work around required.

Before each Approved Optics optical transceiver ships out, it is tested in OEM specific platforms/switches to ensure compatibility for our customers.

Approved Optics is unique in the fact that it not only engineers a legal EEProm attribute solution for the optic without copying the code, but actually tests the optic in the appropriate platform before it ships. This is completely different than the rest of the 3^rd Party Optical Transceiver suppliers in N. America.  Why? Because Approved Optics has made the significant investment in the actual platform switches that are critical to a proper environmental test.

For years, Approved Optics has private labeled for many of the optics brands in the Channel and on the web, and we still do. Other third-party brands and even the OEM’s will source from China, code the EEProm without proper testing, and simply ship the optics to unknowing customers. Approved is the only company in North America that is in the position to environmentally test the optics it ships. We’ve invested over $1.6M in switch/router/expansion card equipment to guarantee that every optical transceiver can be seamlessly integrated in to your IOS.  We make sure that the latest IOS is not only followed and supported by our EEProm attributes, but that every transceiver is environmentally tested before it ships.

For more on Approved Optics Quality, please see Quality.

Programming

The programming for each optical transceiver is unique.  Many of the OEM’s structure their EEProm data and even discrete hardware attributes in order to deter customers from buying anything but their own.  Some of these nuances in the optical transceiver can include: check digit and algorithm verification required by the OEM’s IOS. Other factors include the guarantee of non-repeating serial numbers and the assurance of embedded CLIE and MCU attributes.  Approved has invested heavily in Research and Development to ‘break’ the monopolistic activity by the OEM’s. and offer a quality solution to our clients. To read more about how the Switch OEM’s create technical barriers that push the limits of US Law read Cisco's Secret Franchise.

Approved Optics shares a relationship with the same contract manufacturers that build for of the major OEM’s and we have people on the ground assuring that they are building with the same discrete components. After confirming the exact same discrete hardware components have been included during the manufacturing of the optical transceiver, the 3^rd party provider then needs to address EEProm and Algorithm ‘tricks’ that the OEM has put in place to keep customers from circumventing their brand with quality optics. Approved has invested hundreds of thousands of dollars in multi-platform switch router technology and software, platform specific EEProm readers/editors, and special test software that is unique to Approved Optics. The check digit hardware programming is performed on the transceiver to assure hardware threshold functionality. Approved then verify’s the proper algorithm, in a 3^rd party format for the transceiver, to insure that the IOS will verify and approve the functionality in the port without an error message and with full feature functionality. EEProm attributes are unique to every OEM transceiver - Approved has been able to uniquely parallel the attributes of the OEM without threatening intellectual property laws, so that the optical transceiver will function exactly like an original in the machine and IOS intended. Approved applies a specific serial number sequence code to the NVRAM so that the serial number on that specific transceiver will never replicate in the network. This is very important because the IOS of many OEM’s will check for duplicates and shut down the port.

Upon completed programming, our test engineers verify this process with our unique in-house Q/A software and a follow up environmental test in the actual switch.