Network Visibility Solutions Frequently Asked Questions


Q: Does an nTAP require power?

A: 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.

Q: Will nTAPs drop packets?

A: It depends on the nTAP and the environment. Full-duplex nTAPs will not drop packets but require that the analyzer attached be capable of receiving two feeds from the TAP. Aggregator nTAPs can drop packets if the receive capacity of the analyzer is less than the amount of traffic coming in from the network.

Q: What split ratio do I need when deploying an Optical nTAP?

A: 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.

Q: Can I use standard cables with my nTAP?

A: Yes

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).

Q:  Do nTAPs comply with European standards?

A:  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.

Q:  What is an SFP module?

A:  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.

Q: What is the connector type in the SFPs modules?

A: Optical SFPs (SX, LX, or ZX) have LC connectors; copper SFPs have RJ-45 connectors.

Q:  What is the difference between single-mode (SM) and multimode (MM) cable:

A:  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.

Q:  What do the labels SX and LX signify?

A:  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.

Q:  What is signal attenuation and hw much attenuation does an nTAP cause?

A:  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:
  1. The connections and internal TAP cables absorb and refract a portion of the signal.
  2. 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
60/40        3.0/5.0    3.8/5.7      3.7/5.6   4.7/6.6          2.8/4.8
70/30       2.3/6.3    3.0/7.0      2.9/7.0   3.9/8.0          2.0/6.1
80/20       1.7/8.3    2.4/9.0      2.3/9.0   3.2/10.0          1.3/8.0
90/10       1.2/12    1.9/12.5     1.8/12.8   2.7/13.5 .        8/12.0


Q:  What is the return policy?

A:  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.