PortMaster 3 Frequently Asked Questions
PortMaster 3 Applications
Digital Modem Technology
Primary Rate Interface
Stac Data Compression
A.The PortMaster 3 is ideally suited for high-density WAN service pooling for central sites with InterNetworking Systems and point-of-presence (POP) in-a-box applications.
The PortMaster 3 features Multi-Chassis PPP (MCPPP), which allows multiple calls to be combined across any number of PortMaster 3 devices to form one logical high-bandwidth connection. Because the PortMaster 3 runs cool, several can be stacked in high-density applications. The PortMaster 3 can also be configured with a -48VDC power supply option for Telco applications.
Internet Service Providers (ISPs) can use the PortMaster 3 in multiple, distributed POPs that require the integration of modems, ISDN, CSU/DSUs, communications server and router technology. This integration reduces facility costs by eliminating modem racks, cables, and power supplies. It further reduces the cost of deployment by providing a single console for complete system management. The PortMaster 3 is well suited for high-growth environments that require flexibility and scalability.Q. Can the PortMaster 3 terminate asynchronous PPP (dial-up from a TA) over ISDN, or synchronous PPP dial-up, or dedicated from LAN-to-LAN (using a router) over ISDN?
A.The PortMaster 3 supports V.120 and async-sync PPP. It also supports synchronous PPP for leased line connections.Q. Can I use PortMaster 3 and assign DS0s individually or as a group to allocate bandwidth for specific destinations?
This scenario typically is used in a private network of leased lines where the bandwidth is proportioned as required. Since a T1 is composed of 24 B channels and E1 is composed of 30 B channels, often this method requires good coordination with the telco, such that the proper timeslots for each grouping are correctly identified. Basically, each grouping would become a named 'port' which could have various interface characteristics associated with it, similar to any other interface that can be created on a port with our existing PortMaster.Back to Top
A.True Digital modem cards are high-density digital modems that support either 8 or 10 V.90 modems per card. The PortMaster 3 can support up to 46 PRI T1 or 60 PRI E1 modems via six rear-panel expansion slots. Any combination of modem cards can be used in any slot.Q. How are True Digital modems allocated for inbound calls?
A.The PortMaster 3 allocates True Digital modems in a first-available and fully verified fashion to ensure flawless connections. True Digital modem characteristics make round-robin and other random allocation schemes obsolete and unnecessary.
True Digital modems use digital signal processors (DSPs) with purely digital circuitry that performs identically and error-free every time. An example of a pure digital device is a CPU in a desktop computer. It isn't allowed to make occasional calculation mistakes and must work flawlessly every time it performs a task. The same can be said of the DSPs uses for its True Digital modems.
In addition, The PortMaster 3 architecture allows the central processor to perform a test on each DSP before every call. The DSP memory is tested to verify that it is executing instructions properly. The DSP is automatically removed from the pool if any error is detected.
Some RAS vendors emphasize their round-robin modem allocation, which they claim increases reliability by distributing calls evenly across all modem chipsets. This emphasis on round-robin allocation is an attempt to compensate for inferior analog modem technology. Analog processors are inconsistent and often make errors. Analog circuitry also suffers from high failure rates due to high heat dissipation. Round-robin allocation schemes attempt to deal with the unreliability of the analog modem solution without fixing the root of the problem, bad modems being left in the pool.
In contrast, Lucent's PortMaster 3 uses a fully verified digital solution with no variability on each call so that no user can randomly get the bad modem in the pool.Q. What kind of modem management information can be viewed from our product? Can it be obtained using a GUI?
A.The "show modem" command is used to display the status of all the modems in the PortMaster 3.
The modem status and activity can be displayed in PMVision 1.2 and later in conjunction with ComOS 3.8 and later.Q. What type of dialing is done for dialing to a location?
A.For dialing out with PortMaster 3, use the following command:
- set location location_name analog on | off
Where on is an analog modem dial-out location and off is an ISDN dial-out location.Q. Can the PortMaster 3 be used as a dial-out modem server?
A.Yes, the PortMaster 3 allows users on the LAN to establish a Telnet or Rlogin session for accessing dial-out modems or outbound ISDN lines.Q. Are the True Digital modems flash-upgradable?
A. Yes. True Digital modems provide near-zero obsolescence by providing flash memory for easy software upgrades.Q. Can I use the PortMaster 3 without modems installed?
A.Yes. Without digital modems installed, the PortMaster 3 can be used for PRI ISDN calls, Frame Relay, or leased line service without any additional equipment (Terminal Adapters or CSU/DSUs). If you need to support analog calls, you can add any number of digital modems, in any combination of eight or ten modems per card.Q. If I have an 8-modem card instead of the 10-modem card, does the "show modem" command display the actual number of modems on the card?
A.Yes, it does. ComOS detects the actual number of modems on the modem card of the PortMaster 3 and displays the status of the these modems with the "show modem" command.Q. Are the modem cards hot-swappable?
A. Yes. The modem cards come in two versions: an 8 modem (North America) or a 10 modem (European) card, with up to 6 cards per chassis. Simply follow the procedures outlined in the manual to install (or de-install).Q. What type of modems has Lucent tested for interoperability with the Digital Modem?
A.T1/PRI uses 23 B-channels for data and one D-channel for signaling, so 2 PRIs give you 46 data channels.
Since you can mix and match cards, you can use 3 10-modem cards and 2 8-modem cards to get exactly 46 modems, but the advantage of using 6x8 is that, if a modem goes bad, it's taken out of the pool automatically and you don't have to replace the card right away; you can schedule a time to replace the card. This is particularly useful for remote POPs - instead of getting in a car and going out there Right Then, you can swap out the card (they're hot swappable) the next time you're in the neighborhood. Since the modems are really digital signal processors and run very cool (.8 watts each), we don't actually expect many failures; but if the POP is several hours drive away (or in another city altogether!), some ISPs like the option of having the online hot spares.Back to Top
A.The PortMaster 3 digital modem cards support the ITU-T V.90 modem standard including backward compatability for K56flex modems. The modem software is running on Lucent digital signal processors (DSPs).Q.Can I expect to achieve 56Kbps transmission over existing phone lines?
A.The condition of the local loop will determine the actual performance level achieved. Some lines will support 56Kbps all the time, while other lines are not capable of supporting it. Other lines will permit speeds between 33.6 and 56Kbps.Q.Does V.90 provide 56Kbps in both directions?
A.V.90 is asymmetrical. It provides speeds up to 56Kbps in the downstream, and speeds of up to 33.6Kbps (V.34) in the upstream.Q.What client modems support 56Kbps operation with PortMaster 3 operation?
A.Any V.90 modem will enable 56Kbps operation. This includes modems manufactured by Hayes, Zoom, Boca, Multitech and many other vendors. Please reference the official Lucent V.90 web site for a complete list of compatible products.
Q.Does V.90 provide data compression?
A.No, but the PortMaster 3 supports V.42bis and MNP5 data compression.
Q.Can the PortMaster 3 communicate with older US Robotics X2 client-modems?
A.Yes, at any ITU-T standard up to V.34 (33.6Kbps). Because X2 is a US Robotics proprietary protocol, The PortMaster 3 will only operate at 33.6Kbps with X2 USR devices.
Q. What switch types does Lucent support in the PortMaster 3?
A. DMS-100, 5ESS, NI-2, NTT, KDD, 1TR6, EuroISDN (NET 5), VN2 and VN3.To set the switch type use the following command:
set isdn-switch switch type
Q. Can I allow users to place an analog modem call and/or an ISDN call to the unit?
A. Yes. Arrange to have a single line and your users can dial in with either analog modems or ISDN T/As. The unit will automatically detect and handle each call as required.Q. Can I use the RJ45 port as a PRI or as a T1/E1?
A.Yes. The unit has built-in TDMs that will create the individual DS0 channels (24 in US or 30 for Europe) and associate each as a 'port' on the PortMaster 3.
If you choose to use the RJ45 connector as a T1 or E1 port instead of a PRI, then the TDM can be set "channelize" 56K or 64K channels, as with a CSU/DSU.Q. If the termination of the T1 from the telco is two BNC connectors instead of RJ-45, how do I connect the PortMaster 3 to these connectors?
A.You need to purchase a Balun cable. The Balun cable converts the BNC connectors to the RJ-45.Q. Do I have to set SPID and directory numbers for each B-Channel, similar to the way the BRI products work?
A. No, SPID and Directory numbers are not required, since the single D-channel handles all the call setup and teardown into the telco network.Q. Does the PortMaster 3 support data over voice using PRI?
A.Yes, the PortMaster 3 supports data over voice in ISDN calls. When a call arrives via PRI, the PortMaster 3 checks to see if HDLC frames are present. If the HDLC frames are present, the PortMaster 3 processes the ISDN call. If no HDLC frames are present, the PortMaster 3 brings up a DSP and start-answer tone and handshake with the modem. This is a unique design that permits one phone number for all modems and ISDN calls. The PortMaster 3 also originates voice over data calls.Q. With what 3rd-party vendor products has Lucent tested PortMaster 3 ISDN interoperability?
Q. What kind of telephone signaling does the PortMaster 3 support (loop-start, ground-start, wink-start, etc)? This question relates to terminating analog calls over channelized (fractional) T1?
A.The PortMaster 3 supports dial-up signaling over channelized T1 using wink start and FXS (Foreign Exchange Station) loop start.Q. When I order a PRI line from the telco, can I order a PRI line without T1 or E1?
A.No, you must order a T1/E1 line with PRI signaling. PRI signaling is an additional charge to the T1/E1. On the other hand, when you order a PRI line, the monthly charge for the PRI line doesn't include the T1 (E1). So, be sure to ask the telco about these options?Q. Does the PortMaster 3 support "hardwired" ISDN connections?
A.Yes. All PortMaster products support full-time or "hardwired" ISDN connections.Q. If some areas don't have PRI, can I use the T1 port of the PortMaster 3?
A. Yes, you can use the T1 port as fractional T1. You can also use the PortMaster 3 as channelized T1/E1 for such synchronous WAN routing application as Leased Line and Frame Relay. The PortMaster 3 also supports dial-up (robbed-bit) signaling over channelized T1.Q. Can the PortMaster 3 support a shared D-channel across two PRI lines?
A. Not at this time.Q. If I purchase the single PRI model, can it later be upgraded to a dual PRI box?
A.No. The number of PRI ports is fixed at either one or twoQ. If the PortMaster 3 with two PRI lines is equipped with 24 modems, can the remaining 23 ISDN B channels be used for ISDN calls?
A. Yes. Through the use of a dynamic WAN switching architecture, the PortMaster 3 can automatically switch between ISDN and analog modem calls. A single phone number can front-end all dial-up WAN services across a single or multiple PRI channels.Q. In which geographical areas is the PortMaster 3 approved for use?
A.The PortMaster 3 is currently certified for use in North America, Europe, and Japan.Q. How do I disable CRC4 on an E1 line?
A.set line0 framing fas
Usually this is only valid on French PRI lines. This feature was tested and certified in our EuroISDN testing.
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A. Yes they can be configured for either T1/E1 or PRI. PRI and T1/E1 can be ordered for the PortMaster 3.Q. If some areas don't have PRI, can I use the T1 port of the PortMaster 3?
A. Yes, you can use the T1 port as fractional T1. You can also use the PortMaster 3 as channelized T1/E1 for such synchronous WAN routing applications as Leased Line and Frame Relay. The PortMaster 3 will also support dial-up (signaling and robbed-bit) over channelized T1.Q. What is the labelling scheme be for fractional T1?
A. It will be whatever you want it to be (eg. W0, W1 etc.), as this will be user selectable.Q. What is the command to create a 'channel-list' for a fractional T1?
A. set line 0 fractional
set line 0 group w1 channels 1 2 3 4
set line 0 group w1 64K
Q. What is the default setting for an E1?
A. Framing - crc4
Encoding - hdb3
pcm - a-law
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Q. What ordering information do I need?
A. Ordering a circuit for PRI is basically the same as for a T1. Specify 'extended super frame' and 'B8ZS', then terminate at the de-mark with a 'smart jack'. If you'll be dialing in and out, then you will need to tell your telco that it's a 'two-way' circuit.
You also need to specify 23 B-channels and 1-D channel.Q. What cable will I use to connect to the telco?
A. We are DTE to the telco network, and we use RJ48C with only 4 conductors as shown on the following lists:
1 - R1 Rxdata (Ring) Receive Data from the network 2 - T1 Rxdata (Tip) 3 - Unused 4 - R Txdata (Ring) Send data to the network 5 - T Txdata (Tip) 6 - Unused 7 - Unused 8 - Unused
The cable between a PortMaster 3 and a wall jack is supplied by .Q. Does Lucent support the Caller ID feature in the PortMaster 3 product?
A.Yes, for PRI ISDN, the Caller ID feature is handled by RADIUS. When you turn on a Caller ID feature, the phone number of the caller will be recorded in the Stop record of RADIUS accounting. Caller ID for dial-up T1 will be in a future release of the ComOS.Q. Does the PortMaster 3 have a built-in CSU/DSU?
A. Yes, it does. The PortMaster 3 has an integrated CSU/DSU capable of running T1/E1 speeds.Q. Can I install and configure the PortMaster 3 using the PMconsole for Windows Version 1.1 or PMconsole for UNIX version 3.3.1?
A.No, in order to install and configure the PortMaster 3, you need to use PMVision 1.2 or later and PMWizard 1.0 or later.Q. Does the ComOS 3.5 of the PortMaster 3 support Multi-Chassis PPP Protocol? Does it support OSPF?
A. Yes, both Multi-Chassis PPP and OSPF are supported in the first release ComOS 3.5 of the PortMaster 3.Q. What processor does the PortMaster 3 use?
A.The PortMaster 3 uses a new distributed multi-processor architecture. The main processor is an AMD 486 DE2 running at an internal clock speed of 66Mhz. This CPU is responsible for routing. All other processing is offloaded to other distributed processors. For example, PPP framing is handled by either the WAN interface chipset or the True Digital modem DSPs.Q. What are the benefits of a distributed multi-processor architecture?
A. The PortMaster 3 uses a multi-processor architecture that provides greater reliability and a migration path so you can easily add new capabilities in the future. For example, through the use of an on-board expansion connector, new features such as hardware-assisted compression and encryption can be added later without a sacrifice in performance.Q. Can I attach BRI lines directly to the PortMaster 3?
A.No. The PortMaster 3 supports a PRI interface, which consolidates an equivalent of 23 B (T1) channels or 30 B (E1) channels of service on a single RJ-48 connector.Back to Top
A. The PortMaster 3 supports V.42 data compression for modem connections and Stac LZS/MS-Stac compression for ISDN connections.Q.Why would I need Stac compression for a PortMaster 3?
A. Support of Stac compression is valuable to people who want to maximize the throughput of their ISDN or leased line connections. Whether for telecommuting or for dedicated Internet links, there are frequent situations where large amounts of uncompressed text (e.g. Web pages, regular text documents, e-mail, etc.) need to be transferred from a remote server.Q.Is the PortMaster 3's support of Stac compression hardware- or software-based?
A. The PortMaster 3 provides Stac-based compression through an optional hardware-based card and provides data compression for up to 60 concurrent sessions and high-speed dedicated links.Q.Can my existing PortMaster 3 be upgraded to support Stac-based compression?
A. Yes. You can add on optional Stac-based compression card in the field by simply removing the PortMaster 3's motherboard and installing the new hardware.Q.What kind of increase in performance can I expect from my PortMaster 3 by using Stac compression?
A.Most people can expect to see anywhere from a doubling to a quadrupling in performance when large amounts of uncompressed data are being transmitted.Q.Is the PortMaster 3 compatible with Microsoft Windows 95/NT software-based compression?
A.Yes. Simply select the "Enable Software Compression" dialog box when configuring Dial-up Networking on the Windows 95 or NT client.Q.What version of ComOS supports Stac compression?