Optical-to-Copper Aggregator nTAP Installation – viavidoc.com/observerstart

Optical-to-Copper Aggregator nTAP InstallationRelated information  

Features

 

Key features of the Optical-to-Copper Aggregator nTAP include:

♦ Passive access without packet tampering or introducing asingle point of failure

♦ All traffic (including errors) is passed from all OSI layers foranalyzing

♦ Enhanced security because the nTAP does not require or usean IP address, making it undetectable compared to a SPAN

♦ Allows you to connect and disconnect the analysis device asneeded without taking the network down

♦ Fully IEEE 802.3 compliant

♦ Fully RoHS compliant

♦ Automatic link failover for devices that have an alternatepath

♦ Optional redundant power ensures maximum monitoringuptime

♦ LEDs show power and link status

♦ Optical link is unaffected during nTAP power loss

♦ Front-mounted connectors make installation simple

♦ Optional 19-inch 1U rack mount panel holds up to three nTAP

PartsThe Optical-to-Copper Aggregator nTAP comes with several parts.If any part is missing or damaged, contact VIAVI immediately.

The Optical-to-Copper Aggregator nTAP ships with the followingitems:

♦ Optical-to-Copper Aggregator nTAP

♦ Quick Reference Card

♦ A/C power cord

♦ Voltage auto-sensing universal power supply

Your kit may also contain optionally available parts (for instance,patch cables).

Installing

Prerequisite(s):  

♦ Decide where to place the nTAP and physically mount it, ifdesired. Depending on the form factor purchased, this maybe in a drive bay, rack mount bracket, or wherever it is mostconvenient.

♦ Keep the nTAP horizontal for efficient heat dissipation. 

The Optical-to-Copper Aggregator nTAP splits the full-duplexsignals, allowing the monitoring device access to the data streamwhile maintaining uninterrupted data flow through the monitored

link. The optical network side does not require external power tofunction, however the copper analyzer side does require power. Ifyou were to lose power, the network side is unaffected.

When traffic comes in to Link A, two copies are made in the TAP.One copy is sent out Link B to the switch and the other copy isjoined with a copy of the traffic from Link B and sent out theAnalyzer AB ports to the analysis device(s). A similar thing happenswith traffic that comes in Link B. Two copies are made. Due tohow the TAP is designed, it is not possible for traffic from theAnalyzer side to pass to the Link side. 

 

Caution: Before you temporarily break the linkbetween the device of interest and the network, youmay want to shut down access to that device andnotify users of the down time.

1. Ensure that power is connected to the nTAP. You can providepower to one or both power supply sockets on the backpanel of each nTAP. Connecting both sockets to differentexternal power sources provides fail-safe power redundancyfor the Analyzer side.

2. Disconnect the cable from your device (typically a switch)and connect it to Link B. You want to connect Link B firstbecause it negotiates its network speed first, and Link Athen must use the same speed as Link B. If your link is partof a failover or redundancy arrangement, then connect thefailover device to Link B.

3. Use another full-duplex cable to connect the network device(or primary device in a failover arrangement) to Link A port,thus completing the pass-through link.

4. Connect the Analyzer ports on the TAP to the receiving portsof the monitoring device.

Note: The role of the buffer is to absorb traffic spikesof over 50% full-duplex bandwidth saturation (100%with both sides combined), because the analyzer’ssingle-receive interface cannot receive the trafficfast enough to keep up at line rate. For more detailsabout the Aggregator TAP’s buffer, see Choosing theAggregator TAP buffer size.

An Optical-to-Copper TAP is used when the analyzercommunicates over a different topology than the network. TheTAP has an optical input on the Link side and a copper output onthe Analyzer side. This TAP only functions on 1 Gb networks.

All Optical TAP devices contribute to optical attenuation. See afuller discussion of it in Attenuation.

When the TAP is turned on and correctly connected to functioningdevices, the Link LED indicators are either lit steadily (idle) or

© 2018 Viavi Solutions (2 Jul 2018)

flicker (data transfer) depending on whether there is any trafficpresent.

Light LED Pattern

Power Green — TAP is functioning normally.

Blinking red — An unexpected hardwareproblem has been discovered. Contact VIAVIfor further instructions.

A & B onOptical/Linkside

Unlit — There is no link or the TAP is turnedoff.

Solid green — A link has been established.

Blinking green — A link has been establishedand there is network traffic.

A & B aboveCopper/Analyzerside

Unlit — There is no link or the TAP is turnedoff.

Solid green — A link has been established.

Blinking green — A link has been establishedand there is network traffic.

Blinking red — A network speed other than 1Gb has been detected. Please confirm that thenetwork is 1 Gb. No data will pass through theTAP unless both sides of the TAP are 1 Gb. Thelight blinks red once every five seconds untilthe problem is resolved.

When the Optical-to-Copper Aggregator nTAP experiences powerloss, the following occurs:

♦ If you are using a redundant power supply or the TAPis attached to an uninterruptible power supply (UPS), itprovides power with no loss of network connection.

♦ If you are not using a redundant power supply or UPS, orpower to both power supplies is lost, then:

● The Analyzer ports stop working and the analysisdevice(s) connected to the TAP will go “dark.”

● The TAP continues to pass data between the networkdevices connected to it (firewall/router/switch toserver/switch). In this sense the TAP is passive.

● The network devices connected to the TAP on the Linkports must renegotiate a connection with each otherbecause the TAP has dropped out. This may take a fewseconds.

Error conditions are shown by the LEDs for approximately 10seconds, after which the TAP resets itself (goes back to theCapabilities connection step).

Network administrators who manage optical links have the addedchallenge of dealing with signal attenuation—the rate at whichlight dissipates over a network.

Attenuation is caused by a number of factors and can affect bothnetwork performance and the ability to analyze the network.

Excessive signal attenuation can cause link failure. Understandingsignal levels, selecting the right split ratio on TAPs, and carefullymanaging the location of repeaters can prevent problems. Thissection defines attenuation, explains how it is affected by fiberand other optical elements on a network, and how it can beefficiently managed.

Attenuation is the reduction of signal strength during transmissioncaused by the absorption of light from the materials throughwhich it travels. Greater signal loss equals higher attenuation. Asignal can lose intensity or experience increased attenuation witheach surface or medium it traverses. Many factors contribute tothe attenuation rate of signals including devices such as TAPs andtransmission through optical cables.

Optical signal strength is measured in decibels (dB) and is basedon a logarithmic scale. If a signal attenuates too much, thedestination device cannot identify it or the signal may not evenreach the destination. This is why some optical links depend onrepeaters, which amplify the signal.

FAQ – viavidoc.com/observerstart

FAQProduct dimensions, weight, power consumption, installedoperating system, RAM and details along with photos of theappliance.

Technical specificationsThis section lists the dimensions, power requirements, supportedmedia, and environmental requirements.

Both power connectors are located on the back panel, along withthe model information and serial number.  

Power requirements

AC Input 100-240V 50/60Hz 0.5A

OperationalVoltage

5V (+10%/-5%, < 100 mV ripple)

OperationalCurrent

Typical: <= 1.8 amps; Max: <= 2.8 amps

PowerDissipation

Typical: 8 watt; Max: 14 watt

Environmental requirements

Temperaturerange

32°F - 113°F / 0°C - 45°C (operating): Thefanless cooling design relies on conductionand convection from the nTAP casing. Yourinstallation environment must provideenough cool airflow for the nTAP casing tomaintain an operating temperature less than113°F/45°C.

-52° to +185°F / -47° to +85°C (storage)

Humidity 35-85% (non-condensing)

Supported media

Fiber Multimode or Single-Mode

Connector LC

Fiberdiameter

Multimode: 50/125 µm or 62.5/125 µm

Single-mode: 9/125 µm

Wavelengthranges

Multimode: 850 or 1300 nanometers

Single-mode: 1310 or 1550 nanometers

CopperAnalyzerports

Straight-through RJ-45 cable or crossovercable

Wavelength tolerance ranges

Multimode850/1300(Dual-window)

+/- 20 nanometers

Single-mode 1310 or1550 (Dual-window)

+/- 40 nanometers

Buffer size 256 MB, 512 MB, or 1 GB (depending on TAP)

Dimensions

Width 5.62 in/14.28 cm

Height 1.15 in/2.93 cm

Length 7.79 in/19.78 cm

What happens if my TAP loses power?The 10/100 Copper TAP, Optical-to-Copper Conversion, andOptical-to-Copper Aggregator TAPs do not require any power onthe Link ports. When a loss of power occurs, the Analyzer portsstop working, but the Link ports stay connected without any needfor the endpoint devices to renegotiate their connection.

What latency does a TAP create?Latency is created by the copper ports of a TAP. The latency istypically 200-250 nanoseconds. This is the time it takes to receivea packet, process and copy it, and begin forwarding the copy. Theoptical portion does not introduce any latency.

Are the analyzer ports “send only”?Yes, the analyzer ports are send only. The TAP is incapable ofsending data from the Analyzer side of the TAP to the Link (ornetwork) side of the TAP.

The “A,” “B,” or “AB” ports on the Analyzer side of the TAP mustbe capable of both transmitting and receiving data to negotiatea connection with the analyzer and they do this through thephysical interface. The physical interface is responsible fornegotiating a bi-directional connection with the analyzer andunidirectionally sending data from the TAP to the analyzer.

There is no physical connection between the receive port onthe Analyzer side of the TAP and the TAP’s internal processor.Therefore, the TAP cannot transmit data from the analyzer back tothe Link side of the TAP.

Not seeing traffic at the analyzer from theTAPIf your TAP is not transmitting to the analyzer as you expect,check the following:

♦ The Link is definitely up and running.

♦ The cable connected to the analyzer functions properly. Use adifferent cable to confirm this.

♦ The Ethernet/SPAN or Fiber channel is not divertedelsewhere.

♦ Try swapping the cables between the ports.

♦ The nTAP is receiving power using a VIAVI power adapter. TheLink A and Link B lights flash when there is traffic traversingthrough the nTAP, which indicates the nTAP has power.

♦ Use a light meter to verify there is enough light power forany optical links.

♦ If you are using a TAP with a GigaStor, ensure the driverconfiguration speed is set correctly. Sometimes allowing it toauto-negotiate will enable the connection.

♦ If the system you are monitoring is Linux or UNIX based, youmay have an issue with the Maximum Transmission Unit size.The TCP stack in the UNIX system uses algorithms to producean MTU based on response time from SYN ACK. A small MTUforces a server and client to redo their handshake. Increasethe MTU on your server to alleviate this issue.

© 2018 Viavi Solutions (2 Jul 2018)

Can I daisy chain an Aggregator TAP?Yes, you can daisy chain TAPs, but it is not recommended becauseof the negotiation time and latency introduced by the TAP.Although the latency is very small, if the packets do not reachtheir destination fast enough and the receiving device has a lowMTU (maximum transmission unit), the receiving device couldrestart the negotiation process. For more details, see Not seeingtraffic at the analyzer from the TAP (page 3).

If you experience issues daisy chaining Aggregator TAPs to morethan two analyzers, and you are certain your MTU on the receivingdevices is high enough, contact VIAVI Support for assistance.

I am seeing CRC errors on my networkIf you are seeing an uncommonly high number of CRC errors, thiscould indicate that there is an issue with the TAP, but it may alsoindicate that the TAP is fine and there are other problems on yournetwork. Contact VIAVI Technical Support for assistance.

VLAN tags not visible at the analyzerAll TAPs pass VLAN tags with the packets. If you are not seeing theVLAN tags at the analyzer, check the following:

♦ On the switch:

● Confirm that the SPAN was created to pass VLAN tags.Sometimes SPANs are created and passing VLAN tags isnot enabled.

● Confirm the communication between the switch andthe router is passing the VLAN tags (normally thecommunication between them is not a trunk).

♦ On a GigaStor, if you are using one:

● Confirm the capture card has been enabled to receive orpass VLAN tags.

Managing attenuationManaging signal attenuation is critical for running a network atoptimal performance.

If signal attenuation is too high, destination devices may notbe able to establish a link or receive network traffic. Repeaterscan help, but they can be costly and inconvenient to implement.In general, unless a signal must travel a long distance or iscompromised by patch panels, there should not be a problemusing the 50/50 split ratio. The most efficient and cost-consciousway to manage attenuation is to measure signal levels throughoutthe network and place repeaters only when and where they areneeded.

To determine if a light signal is at an acceptable level at anypoint on a network, it is helpful to use an optical power meter.Optical power meters measure signal power at a port, helpingyou determine whether a device is receiving a strong enoughsignal and thereby identifying if repeaters need to be placed. Themeters are typically inexpensive and are offered from a number ofvendors.

MemoryFully optical TAPs do not have internal memory or any electroniccomponents and are strictly a pass-through wherein a copy of thedata is made. TAPs with any copper connections have two distinctand separate memory stores.

The two memory stores are non-volatile memory and volatilememory. They are not connected in any way and no data canmove between them. The non-volatile memory provides certainfunctions that make the device work and cannot be modified orchanged during normal operation of the device. Volatile memoryholds network data as it is copied and passed through the device.Turning off the device clears any data in the volatile memorybuffer.

Maximum frame sizeThe maximum frame size allowed through an nTAP is up to 16K;64K super jumbo frames are not supported.

Technical Support

NorthAmerica

1.844.GO VIAVI / 1.844.468.4284

LatinAmerica

+52 55 5543 6644

EMEA +49 7121 862273

APAC +1 512 201 6534

All OtherRegions

viavisolutions.com/contacts

email customer.care@viavisolutions.com

Support hours are 7:00 A.M to 7:00 P.M. (local time foreach office).