Posted on November 28, 2011 by bboxadmin
These switches perform as promised year after year, using internal mirrors to optically move data between fiber ports. Air-gap isolation provides a physical break in circuit connections for secure communications. This makes them ideal for government, healthcare, or other applications where a private, data-sensitive network connects to a publicly accessible one.
Fiber Optic A/B Switch, Latching, ST
Unlike conventional electronic switches, these switches are not complex devices with vulnerable circuits that you need to closely monitor and protect from intrusion, component failure, or interference.
Even without the complexity, they’re reliable in mission-critical environments. Their jewel-like micro-mirrors are bonded to precise positioning servos, controlling the reflections of the optical data beams. Data passes through, maintaining optical communications even when power is removed. The “latching” versions latch mirror movement mechanically into a selected position and hold it there without the need for continuous electrical power.
The A/B switch has unique loopback capabilities. Using loopbacks, you can verify the integrity of your backup fiber link while still connected to your primary fiber link. This is especially useful in failover applications where you want to continuously test the “unused” circuit to ensure that it’s available if needed.
Filed under: Blog Posts | Tagged: electronic switch, Fiber Optic, Switches | 1 Comment »
Posted on November 23, 2011 by bboxadmin
Session Initiation Protocol (SIP)
is used for controlling multimedia communication sessions over an IP network. Common applications include voice over IP (VoIP), videoconferencing, streaming multimedia, on-line gaming, and instant messaging. SIP is the protocol of choice for VoIP, and is used to create, modify, and terminate VoIP sessions, including functions such as call transfer, conference calls, and call hold.
This very high-level protocol operates primarily in the Application Layer (Layer 7) of the OSI model. Because SIP runs independently of the Transport Layer (Layer 4), it works with most transport protocols, including TCP and UDP.
Much like HTTP, SIP is a text-based protocol. SIP messages contain only as much information as is needed for each session, so it’s very efficient and can expand and contract to meet each application’s specific requirements. This extensibility makes SIP incredibly versatile, enabling it to cover functions ranging from simple VoIP calls to complex multi-user videoconferencing.
Filed under: Blog Posts | Tagged: osi layer, Session Initation Protocol, SIP, voice communication, VoIP | Leave a Comment »
Posted on November 17, 2011 by bboxadmin
This is the fifth and last post in our series on counterfeit and substandard cable.
Because of all the publicity counterfeit and substandard cable has garnered, especially in the past year, we want to explain how Black Box addresses performance and safety issue through ETL Verification and independent burn testing.
Every three months, an independent Intertek inspector visits us. He goes into our warehouse where he randomly selects GigaBase® CAT5e and GigaTrue® CAT6 channel components for ETL testing. To ensure that “good” product isn’t pulled only from the most popular items, he mixes up his product selection. In one visit, he may choose green jacks to be tested with white cable. The next, he may choose gray cable and yellow jacks. The items are then sealed up and sent to the ETL lab for testing.
Filed under: Blog Posts | Tagged: Black Box, cable, ETL, Intertek | Leave a Comment »
Posted on November 8, 2011 by bboxadmin
One of the most aggravating infrastructure challenges occurs when you get asked to put a workstation in some inconvenient, too far, difficult-to-wire spot. If there’s a room at the far end of some unused hallway, or a shack at the edge of campus, chances are you’re going to get a request for an Ethernet port there.
Whenever you need to put a connection in one of these types of places, your first move should be to check to see if there’s any existing cable that can be adapted for Ethernet by using Ethernet extenders. Most modern buildings have unused voice-grade wires or unused coax. Additionally, many campuses have installed 25- or 50-pair telephone trunk cables between buildings. You can hijack these unused wires for Ethernet use.
A simple option for expanding your corporate or service-provider LANs!
Ethernet extenders are easy to set up—all you need to do is to plug in one at each end of the twisted-pair wire or coax. Sometimes you’ll also need to set a DIP switch for local or remote operation. Once the Ethernet extenders are installed, there’s nothing to configure, and the extenders are transparent to network operation.
Filed under: Blog Posts | Tagged: Ethernet, Extenders, networking | Leave a Comment »
Posted on November 3, 2011 by bboxadmin
This is the fourth in a series of posts about counterfeit and substandard cable.
1. UL® number and hologram: None, fake, or illegitimate. If there is no UL® number or hologram, that’s an instant tip-off. Even if there is a number or hologram, you can look up the cable on-line at UL® to see if it’s verified. Sometimes, even if there is a legit UL® number, it’s possible that it was copied from “good” cable. UL also posts alerts on unauthorized numbers on its website.
2. ETL logos. Counterfeiters use them whether they are earned or not. Ask the seller for the ETL test results. You can also check the ETL website for a directory of verified cables.
3. Printing/Legend. Is the printing poorly done on the box and the cable? Are there any typographical or grammatical errors? Check the UL® logo. It should have the letters UL arranged diagonally (descending left to right) with a circle with a small ® symbol directly below the U. Does the cable legend also have the proper markings?
GigaTrue® 550 CAT6, 550-MHz Solid Bulk Cable, 4-Pair, 1000-ft.
4. Color. Does the color match previously bought cable?
Filed under: Blog Posts | Tagged: cable, counterfeit cable, ETL, UL | 2 Comments »