Supporto > FAQs (Frequently Asked Questions)

What is Zero Delay™?
Zero Delay™ is a unique tap technology offered only by Net Optics that prevents packet loss or delay should the Tap lose power. Zero Delay technology prevents link downtime by eliminating the typical 10ms delay caused when other Taps lose power. That small delay can cascade into much longer delays as devices on the link detect a failure and attempt to re-establish communication.

What is Virtual Zero Delay (VZD)?
VZD is a new, patent-pending technology from Net Optics designed to improve network reliability when using copper taps. Net Optics’ innovative Virtual Zero Delay circuitry guarantees that iLinkAgg™ in-line copper connections will never lose their links when power goes off for whatever reason - such as power failures or during planned power up and power down events. In the past, link renegotiation has been a major challenge for copper taps, costing precious seconds or minutes of link downtime when Tap power transitions. The VZD eliminates those lengthy renegotiation cycles by preserving the link state through power transitions, as if no break existed.

What is Link Fault Detect™?
Link Fault Link Fault Detect is a Net Optics feature that gives devices connected to the Tap critical information about link status. If either side of the bi-directional link fails, the Tap immediately communicates the fault to the other device, reducing the time required to activate a redundant path. This technology is found on the Copper GigaBit and 10/100/1000BaseT Taps, Bypass Switches and Port Aggregator IPA-CU3.

What is Active Response?
Net Optics products with Active Response allow network personnel to set their network devices to send active response packets such as TCP resets, ICMP messages, or ACL changes into the tapped link. Normally, Tap monitor ports are transmit only and do not allow traffic to flow back into the active link.

What is Fast Path™?
Fast Path is a technology found in the Net Optics Bypass Switches that supports fail-open monitoring with any Gigabit in-line device when it shares the same power source as the in-line appliance. As long as the Bypass Switch is receiving power, it diverts network traffic to attached in-line devices. When power is lost, Fast Path maintains network link integrity with high-speed switching so the network link is maintained but is no longer routed to the in-line device.

Are Net Optics Taps passive devices?
All Net Optics copper taps are completely passive. Simple Fiber Taps require no power and are completely passive. They are not a point of failure in the event of power loss. Net Optics also offers Zero Delay technology on most 10/100 tap product lines which guarantees no packet loss if the Tap loses power.

I am monitoring my network segment via a Span (mirror) port on my switch.   How will I benefit by using a Net Optics Tap?
Network Taps create permanent access ports for passive monitoring by splitting or regenerating the full-duplex network signal. The monitoring device connected to the Tap receives traffic as if it were in-line, including all errors. In contrast, a monitoring device connected to a switch Span port does not see all traffic. Corrupt network packets, or packets below minimum size, are usually dropped. Switches also eliminate Layer 1 and select Layer 2 errors, and are constrained by the bandwidth capacity of the Span port. In addition, by using a Tap you put less load on your switch buffer and can eliminate "resets" by the switch.
For more information, please download the following white paper:
Technical Comparison: Taps vs. Span Ports

Do GigaBit Copper Taps support Gigabit speeds only, or up to 1000 Mbps?
The Net Optics GigaBit Copper Tap was designed to support 1000 Mbps only. Net Optics offers a 10/100/1000 Copper Tap for flexible connectivity.

Do Net Optics Taps participate in link negotiation? All Fiber, WAN, and 10/100-based Taps are pass-through devices that do not participate in link negotiation. Net Optics Gigabit Copper and 10/100/1000 Taps negotiate a separate link with each network device.

Do Net Optics taps support POE (Power Over Ethernet)? 
Currently the 10/100 Taps (part number TP-CU) and the Teeny Tap (part number TP-CUTT-USB) are the only taps that support POE. Net Optics 10/100/1000 Network Taps will support POE in the future.

I have a 10/100BaseT Tap and can’t get link established through the Tap.  Do I have it cabled correctly? 
When connecting Tap network ports to Switches, Routers, and Hubs, use straight-through cables. Use a crossover cable and a straight-through cable when you are connecting similar devices, such as Switch-Switch (DTE-DTE), to the Tap. Use straight-through cables to connect hubs, switches, or NICs to the Monitor Ports.
Tap'd In Video: 10/100BaseT CAT5 Cabling

I have installed a Net Optics Fiber Tap and verified that network traffic is passing through the Tap but I do not see traffic coming out of the Tap Monitor Ports. What should I check?
If the Transmit and Receive portions of your fiber optic cable are crossed on the Network Ports of the Tap, you will see traffic pass through the Tap but nothing coming from the Monitor Ports. Check to see that the cables going into the Network A and B ports on the Tap are as follows: TX = In, RX = Out.

I noticed Net Optics Fiber Optic Taps are offered in multiple split ratios.  Why would I need the different split ratios?
A split ratio is the amount of light that is re-directed from the network to the monitor ports. With higher split ratios, less light is re-directed from the network link to the monitoring link, ensuring adequate light power for the network link. Click on the following link to download our Split Ratio Reference Chart.
Net Optics Fiber Split Ratio Reference Chart

What is the difference between ATM Fiber Taps and GigaBit Fiber Taps? Can they be used interchangeably?
ATM Fiber Taps are manufactured and tested for use with an LED light source and GigaBit Fiber Taps are manufactured and tested for use with a Laser light source. You should avoid mixing Tap types to ensure insertion loss and split ratio accuracy and prevent ATM Taps from being damaged by laser light.

I have had a Net Optics Fiber Tap for a couple of years and noticed that the light loss budget seems higher. Do the Fiber Taps go bad?
Fiber components of Net Optics Fiber Tap’s are designed to last for the life of your installation. Dirty or loose connectors will cause a loss of optical power. Cleaning the connectors will restore light levels in most cases.

Will Net Optics Copper Taps work with Category 5, 5e, and 6 cables?
Yes, Net Optics Taps work with all cable types. When mixing and matching different cable types, the connection will operate at the lowest rated cable. Net Optics recommends that you use Category 5e (CAT5e) cables or better with all Gigabit copper devices. All Net Optics copper Taps are shipped with CAT5e cables.

Does Net Optics offer any taps products for 10 Gigabit networks?
Yes, Net Optics offers a full range of Tap and Regeneration (Span or In-Line) and Bypass Switch products for all 10 Gigabit interfaces including 10 GigaBit SR, 10 GigaBit LR, and 10 GigaBit ER.

I noticed that Net Optics offers 10 Gigabit taps and regeneration products in three different interfaces. How do I know which one to order?
The three different interfaces are based on different laser sources and fiber core diameters. 10 GigaBit SR is designed for use with 850 nm lasers and comes in two different fiber core diameters, 50 um and 62.5 um. 10 GigaBit LR is designed for use with 1310 nm lasers and 8.5 um diameter fiber core. 10 GigaBit ER is designed for use with 1550 nm lasers and 8.5 um diameter fiber core.

What does iTap mean?
Intelligent is the “i” in iTap. The iTap concept is a new innovation that delivers more value to our customers in the form of actionable information about network status. iTaps help network managers to use their network security and monitoring devices more effectively, reduce response time to network anomalies, and build a pervasively aware network.

How will iTap work with my RMON probes and analyzers?
iTap is not a replacement for these devices. iTap supports and complements RMON probes and analyzers by making it easier to know where and when to use them. Although the iTap does provide network traffic information, it is best at establishing baseline and early warning metrics.

How do I control the iTap and monitor traffic statistics?
iTap features command line, browser, and SNMP interfaces for controlling the iTap and monitoring link status information. The command line interface (CLI) is via an RS232 port and requires a computer with terminal emulation software. The browser interface is Net Optics Web Manager and requires a computer with any browser. The SNMP interface is Net Optics System Manager and requires a computer with Windows 7, Windows Vista, Windows XP, Windows 2000 or Windows 98.

What control options does the iTap have?
Management Port and Monitor Port Control – To control access to the iTap, you can use the CLI to turn off the Management Port, preventing access by Net Optics System Manager and other SNMP tools. You can use any interface to turn off the Monitor Ports to prevent unauthorized access to the link via the iTap. You also have the option to prevent the front-panel display from showing utilization and peak data.

Utilization – To trigger an alarm when utilization levels are too high, you set a threshold as a percentage of bandwidth. When traffic levels pass this point, the alarm LED illuminates and alarms are sent to remote interfaces.

Resets – At any time you can reset the Threshold Alarm LED, Peak Time, Date, and clear all the statistical counters.
 
What information does the iTap provide?
The iTap provides status, utlization, and traffic statistics.

Status

•    Link up or down
•    Power on or off
•    iTap internal error

Utilization

•    Current utilization level
•    Highest traffic peak
•    Time and date of highest peak

Statistics

•    Total Packets
•    Total Bytes
•    CRC Errors
•    Packet Collisions
•    Undersize Packets
•    Oversize Packets

What alarms does the iTap have?
The iTap has utilization threshold, link, power, and internal power alarms. The iTap indicates a threshold alarm from a LED in the front panel as well as the three interfaces. All other alarms are accessible from the remote interfaces. The iTap also supports SNMP traps for these alarms compatible with third-party SNMP tools.

Can I use iTap with my SNMP management tool?
Net Optics Management Information Base (MIB) is compatible with all SNMP V2 tools. iTap SNMP functions work with HP OpenView and IBM Tivoli.

Do you receive the full line rate data stream with Port Aggregators?
The Net Optics Port Aggregator Taps combine traffic from both sides of a full-duplex link and send all traffic, up to the capacity of the Monitor Port, to the attached monitoring device. When utilization levels exceed the capacity of the Monitor Port, the Port Aggregator Taps buffer overflow data and send this data as soon as utilization drops below the capacity of the Monitor Ports.

What are the memory options for the Port Aggregator Taps?
The 10/100 Port Aggregator contains 2MB (1MB each side) to handle buffer overflow when the cumulative utilization spikes above 100%. The GigaBit Fiber and Copper Port Aggregator Taps come standard with 64MB of onboard memory (32MB each side). There are optional memory options of 128MB and 256MB. iTap Port Aggregator’s are only offered with 256 MB of buffer memory.

I noticed a DIP switch on the back of the 10/100 Port Aggregator Tap. What is that used for?
The DIP switch is used to set the negotiation parameters of the Tap. By default, the 10/100 Port Aggregator Tap is set to Auto-Negotiation. If your devices are set for fixed speed and duplex, it is recommended you set the Port Aggregator to match. For more information, see your Installation Guide.

Do you send all traffic to the Link Aggregator monitor ports?
Yes, all traffic is sent to the Monitor Ports until the sum of traffic reaches the capacity of the Monitor Port. Any traffic above this threshold is dropped.

Is there any memory on the Link Aggregators?
Currently, we do not offer memory on the Link Aggregator Taps. However, we are working on adding memory in a future release.

What is a Regeneration Tap?
Regeneration Taps provide passive monitoring access for multiple devices. Net Optics' passive Regeneration Taps enable real-time, simultaneous monitoring of a network link or Span port by up to eight protocol analyzers, intrusion detection systems, and other devices for network monitoring and troubleshooting.

Are Net Optics Regeneration Taps passive devices?
Yes, Regeneration Taps are completely passive devices.

How is a Regeneration Tap different from a Matrix Switch?
Regeneration Taps provide passive monitoring access for multiple devices. Net Optics Matrix Switches provide passive monitoring access across multiple networks for analyzers to perform real-time monitoring and analysis. Matrix switches greatly increase monitoring efficiency and leverage analyzer investments.

What are the different options available with Regeneration Taps?
The Regeneration Taps come in 2, 4, and 8 monitor port versions. They also support all major network interfaces such as 10/100, Gigabit, and WAN (OC3 and OC12). Regeneration Taps also come in Span and in-line versions. Span Regeneration Taps give users the ability to monitor up to two Span ports independently with multiple resources, reducing the burden on your switch. The in-line models tap one critical full-duplex link and make up to eight copies of that link.

What is a Bypass Switch?
Bypass Switches protect the link against power loss from the in-line IPS or security appliance. When the Bypass Switch is receiving power, traffic is routed to the in-line appliance. If power is lost or the appliance needs to be removed for maintenance, the Bypass Switch routes traffic past the in-line device using Fast Path technology preventing link downtime. See diagram below:



How does a Bypass Switch with Heartbeat work?
The Optical Bypass Switch with Heartbeat protects against power failure, physical link failure, and application failure on the in-line appliance. The switch checks the path through the in-line appliance by sending a packet every second from Monitor Port C. The switch validates the path when it receives the packet on the Monitor Port D. If the switch does not receive the packet as expected three times in a row, the switch automatically enters Bypass ON mode.

What is the heartbeat packet?
The heartbeat packet is a 64 byte IPX packet sent once every second from the Monitor Port C. You can change the default timing of the heartbeat packet and the heartbeat packet from the bypass switch CLI.

Packet Contents (Hex)           Description
-----------------------------             ----------------

00 50 C2 3C 60 00                   MAC DA Net Optics
00 50 C2 3C 60 01                   MAC SA Net Optics
81 37                                            Packet Type IPX
FF FF 00 30 00 00 00 00
40 04 EC A2 C6 13 01 02
C6 13 01 01 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00
82 A2 BA 71                                CRC

Can you re-configure the Heartbeat interval?
Yes, you can configure the Heartbeat interval and also the numbers packets missed before the Bypass Switch enters Bypass Enabled Mode. The Bypass Switch has an RS232 port and a command line interface for programming Bypass Switch options. See the Installation Guide for complete information.

What is Active Response?
Net Optics products with Active Response allow network personnel to set their network devices to send active response packets, such as TCP resets, ICMP messages, or ACL changes, into the tapped link. Normally, Tap monitor ports are transmit only and do not allow traffic to flow back into the active link.

Do all Net Optics products support Active Response?
No, only products designated Active Response support this feature. Currently, the 10/100 BaseT Port Aggregator (Part Number’s PAD-CU-AR, PA-CU-AR and PA-CU-PCI-AR) and Regeneration Taps (Part Number’s RGN-CU-AR-IL2, RGN-CU-AR-IL4 and RGN-CU-AR-IL8) support this feature.

Can the Active Response feature be turned off on the products supporting Active Response?
Yes, the Active Response feature is enabled and disabled from a Dip switch on the back of the Tap. On the single-port Active Response Taps, switch 8 enables/disables this feature. On the Regeneration Active Response Taps, switch 4 enables/disables this feature. Below is an example of the Dip switch for the Regeneration Active Response Tap:

Do you offer any Media Conversion products?
Yes, Net Optics has several different Media Conversion products.  Click here to see the variety of Media Conversion products we offer.

What´s the difference between Monitor Load Balancing and Application Load Balancing?
A monitoring load balancer performs a very different function than an application load balancer. Both devices distribute traffic to multiple attached devices, but the application load balancer has another critical function. That function is to make the pool of application servers appear to the network as a single server. Application requests come into the application load balancer at a single IP address, let's say 192.168.131.47. The load balancer proxies all of the requests and then directs them to the servers in the pool, with addresses that may be, for example, 10.60.4.2, 10.60.4.3, 10.60.4.4 ... When the responses return from the application servers, the load balancer proxies them again and makes them look to the network like they are coming from 192.168.131.147. Notice also that the application load balancer only needs a single port on the server side (though it may have multiple ports to achieve greater bandwidth). The port connects to a switch and the switch channels the traffic to the correct server.

Monitoring load balancers such as Net Optics' xBalancer do not provide this proxying function; rather, they pass traffic transparently. Monitoring tools are not IP addressable; they sniff traffic promiscuously. Therefore the monitoring load balancer needs a port for every tool in the pool, and a direct (not switched) connection from port to tool. The monitoring load balancer directs flows of traffic to the different tools by sending them to different ports, not by IP addressing.

So monitoring load balancers are real load balancers, but they are not application load balancers. Besides, application load balancers have evolved into Application Delivery Controllers, adding many other capabilities such as caching, compression, and rate-shaping to optimize application performance—which is why they tend to be more expensive than monitoring load balancers. As in most situations, you need to use the right tool for your job to get the best job done.


RJ45 Serial Console Cables - RS-232 running through RJ45 connectors
When RS-232 serial is run through DB9 connectors, there aren't many problems these days. We seem to have finally gotten our RTSs and DSRs straightened out. And when was the last time you used any settings besides 8,n,1,n?


But now a-days, everyone—including Net Optics—is using RJ45 connectors for their serial consoles. And guess what? There are no standard pin assignements. Just look at this page, which shows 31 different RJ45 serial pinouts that have been used on various pieces of equipment: http://www.conserver.com/consoles/Signals/signals.html

Readers of this blog will be interested in two particular pinouts, the one we use and the one Cisco uses. At New Optics, we picked a pinout for which it is easy to find an RJ45-to-DB9 adapter; and, to make it even easier, we put one in the box with each of our affected products. However, our pinout is not the same as Cisco's:

RJ45 Pin	Net Optics	Cisco
1	<not used>	RTS
2	<not used>	DTR
3	<not used>	TXD
4	GND	GND
5	RXD	GND
6	TXD	RXD
7	CTS	CTS
8	RTS	RTS

The picture at the top of this blog entry shows how you would wire a cable to connect a Net Optics device to a console wired Cisco's way. If you don't want to build a cable, and you have a DB9 adapter for your Cisco cable, you can use the DB9 adapter we shipped with the product to go: RJ45-to-DB9-GenderChanger-DB9-RJ45.