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RoHS Compliance Declarations
- Analyzing Full-Duplex Networks Through SPANs, Port Aggregators, and TAPs
- Attenuation and Network Performance
- Optical Signal
Frequently Asked Questions
Does an nTAP require power?
Any nTAP with copper connections to the network or analyzer will require power to copy the data stream and send it to the monitoring device. However, the data stream continues to pass through the nTAP to the network even if power to the nTAP fails.
"Pure" optical nTAPs (fiber in and out) require no power to operate.
Can I use a full-duplex nTAP to provide visibility into a half-duplex connection?
Yes, as long as your monitoring device is equipped with a dual-receive capture card.
An nTAP sends copies of the TX and RX of a half-duplex signal out through separate "send" ports to the monitoring device. If your monitoring device is equipped with a dual-receive capture card, you will be able to view both streams of data. However, if your monitoring device is equipped with only one receive port, it will only be able to view one stream of data at a time.
The NIC in my analysis device has a single "receive" port. Will I get visibility into a full-duplex connection with an nTAP?
Yes, but you will only be able to view one side of the full-duplex link at a time. This is not recommended. An nTAP sends copies of the TX and RX of a full-duplex signal out through separate "send" ports to the monitoring device. If your monitoring device is equipped with a dual-receive capture card, you will be able to view both streams of data. However, if your monitoring device is equipped with only one receive port, it will only be able to view one stream of data. To view the entire full-duplex stream for analysis, the monitoring device should have two receive ports and the ability to aggregate TX and RX into a single stream.
What split ratio do I need when deploying an optical nTAP?
If all devices between the connections are within 30 meters of the nTAP, a 50/50 split ratio is ideal. While we recommend that you always test the strength of your optical signal with a meter, for longer hauls, it may be necessary to choose a split ratio that diverts more of the signal to the distant device.
Can I use standard cables with my nTAP?
To connect a monitoring device to an optical nTAP:
Split a duplex cable (or use two simplex cables) and connect one end of each of those sides of the cable to the "send" ports on the nTAP, and the other end of each of those sides of the cable to the "receive" ports on the monitoring device's NIC. We also offer a convenient analyzer (or splitter) cable to ensure this connection can be made without error.
To connect a monitoring device to an nTAP with copper outputs:
Use standard straight-through RJ45 Ethernet cables (cross over cables cannot be used with 10/100 Copper nTAP).
Do nTAPs comply with European standards?
Yes. All copper nTAPs are CE certified to meet European standards for RF emissions. Optical nTAPs do not require RF certification because they are not electronic devices.
What is an SFP module?
For flexibility in link access, some nTAPs include SFP (Small Form-Factor Pluggable) technology. SFPs are hot-swappable modules that can access different media types (Optical SX, LX, ZX, and Copper TX) and support varying data rates (10/100/1000). The Copper to Optical Conversion nTAP supports SFP technology, so the modules can be swapped out depending on the analyzer's interface. For example, if a conversion nTAP currently has an SX SFP for the analyzer connection, and the analyzer has an LX interface, the current SX-based SFP can be swapped out with an LX SFP.
What is the connector type in the SFP modules?
Optical SFPs (SX, LX, or ZX) have LC connectors; copper SFPs have RJ-45 connectors.
What is the difference between single-mode (SM) and multimode (MM) cable?
Single-mode (SM) and Multimode (MM) cables differ by which wavelengths of light they are optimized for and the number of light signals they support. MM fiber is the most common cable and supports multiple light signals at various wavelengths simultaneously. The fiber core comes in 62.5 or 50 microns. SM fiber has a much smaller core (≈ 9 microns) and can only support a single wavelength of light signal. Because the SM cable has a smaller core and supports only one signal, there is less attenuation and data can travel longer distances.
What do the labels SX and LX signify?
SX is the IEEE 802.3z standard for Gigabit Ethernet over short distances for multimode fiber cable. LX is the IEEE 802.3z standard for Gigabit Ethernet over longer distances for single-mode fiber cable.
What is signal attenuation and how much attenuation does an nTAP cause?
Attenuation is the reduction of signal strength during transmission. Greater signal loss equals higher attenuation. A signal can lose intensity, or experience increased attenuation, with each surface or medium it traverses. As with all devices inserted into an optical link, one side effect of TAP usage is signal attenuation.
A TAP attenuates the signal for two reasons:
- The connections and internal TAP cables absorb and refract a portion of the signal.
- A portion of the signal strength is "siphoned off" and sent to the analyzer. How much of the signal strength is redirected for analysis depends on the split ratio.
An optical split ratio must be designated for each optical TAP. In most cases, a 50/50 split ratio is ideal, providing sufficient light to the network and to the monitoring device. However, there may be special cases that require an alternative ratio in order to meet signal power needs. For example, if a TAP is cabled close to the analyzer NIC (network interface card), and the link under test requires a long cable run, you may want to provide more power back to the network than the monitoring device. However, it may be more appropriate to implement a repeater on that segment. If you do choose an alternate ratio, keep in mind that the signal has to be strong enough for it to be interpreted at the destination. The table below shows an example of attenuation caused by a TAP at different split ratios. The rate of TAP attenuation can vary by TAP manufacturer.
Maximum insertion loss per split ratio
|Split Ratio||Multimode 62.5 μm||Multimode 50 μm||Single-mode 9 μm|
|(1300 nm)||(850 nm)||(1300 nm)||(850 nm)||(1310/1550 nm)|
|50/50||3.9/3.9 dB||4.7/4.7 dB||4.5/4.5 dB||5.5/5.5 dB||3.6/3.6 dB|
Are nTAPs capable of passing data from their analyzer ports back through the TAP to the network?
In the diagram to the right, you will see that a copy of the data coming out the right side of the processor chip is sent to the device attached to the "Analyzer" side of the TAP.
The "A" and "B" ports on the "Analyzer" side of the TAP must be capable of both transmitting and receiving data in order to negotiate a connection with the analyzer and they do this via the PHY.
There is no connection between the receive port on the PHY and the processor. Therefore the TAP has no ability to transmit data from the analyzer back to the Link side of the TAP.Includes our part numbers: TCTH-K, TCHG-K, TCOTHG-XX-K, TAC256-K, TAC512-K, TACO256-K, TACO512-K
What is the return policy?
At Viavi Solutions we are focused on customer satisfaction, we allow refunds on products within 30 days of purchase (purchase date on the invoice), provided the product is complete, in working order and both the product and packaging material is undamaged.
All returns must have a valid RMA number issued and the RMA number prominently displayed on the outside of the return shipping box. Before returning an item please contact our Technical Support Group at 800-526-7919 (1-952-358-3800) to work through any technical issues, or to be issued an RMA number. Should the product be incomplete, damaged or the packaging is damaged, a restocking fee will apply.