Cyclades-PR4000 Frequent Asked Questions
FAQ

(Last updated on 02/2001)
 

1. Is the PR4000 "V.92-ready"?

   Yes, the PR4000 is V.92-ready.
   In our opinion, it is somewhat misleading to advertise "we are V.92 ready". As of today, there is no practical implementation of V.92. There are many experimental implementations of the proposed standard and they are useless until there is interoperability and V.92 support becomes possible in the client side. Some companies advertise that meaning that they will be able to support V.92 in the future without hardware change (or even have an experimental implementation today), trying to pass the false idea that they have V.92 before the competition.
   V.92 is a new proposed modem standard (as of 02/01) that improves on the V.90. It promises shorter connection times and slightly higher potential upstream bandwidth (downstream bandwidth is still limited to a theoretical maximum of 56Kbps). Modem standards take some time to become practical because the many vendors have to clear interoperability and implementation issues. In the past, widespread adoption of a new modem standard took from several months to a couple of years.
   The digital modems on the PR4000 are implemented with generic DSPs with 100% downloadable modem software. That means that when V.92 becomes a practical standard, the PR4000 will be able to support it with a simple software update. We share modem technology with some of the largest RAS vendors in the market, so we will have it as soon as they have. We do not intend to include experimental versions of V.92 implementations in the product for marketing sake before this becomes practical or useful.

2. What types of clients can connect to the PR4000?

   The PR4000 can terminate both analog (V.34/V.90 modems with POTS lines) and digital calls (ISDN modems with ISDN-BRI lines).

3. How many users can I support with the PR4000?

   The PR4000 supports up to 60 (E1) or 48 (T1) simultaneous connections in its maximum configuration.
   A rule of thumb for ISPs is to allocate one line for each 10 dialup customers. Using that rate of over-subscription, a PR4000 can roughly serve 600/500 users.

4. The PR4000 uses modules with 8 digital modems, how many of them should I buy?

   Clients using ISDN modems with ISDN-BRI do not require modems in the PR4000. Clients using analog modems (V.34/V.90) with analog phone lines require a modem inside the PR4000 to be able to connect.
   So, the answer to this question depends on whether your clients will be using analog phone lines or ISDN-BRI lines.
   In an ISP environment, usually you have to assume that the great majority of the users will be using analog lines and you should get 24 modems per T1 trunk or 32 modems per E1 trunk. If you know your clients are connecting through ISDN-BRI lines you can use less or even no modems at all.

5. What are the PR4000 external connections. Do I need to buy any additional equipment?

   The PR4000 is a highly integrated product. It connects to the Ethernet LAN and to the T1/E1 trunks and has an optional WAN routing port. There is no need for external modems, DSU/CSUs, or routers. The PR4000 is a POP-in-a-box (some customers have only a PR4000 at POP sites).

6. The T1/E1 interface uses an RJ-45 connector. Do I need a Coax connector?

   The PR4000 provides the T1/E1 interface on an unbalanced 120 Ohms RJ-45 connector. This interface can be connected directly to the T1/E1 communication line. In some countries, the E1 lines are provided on a balanced 75Ohms Coax interface. In those cases, you need an impedance/connector converter (balum). Balums can be purchased in any electronic store. In some countries, Cyclades has made arrangements with the local distributor so that the customer already receives the balum with the PR4000.

7. How does the PR4000 handle user authentication and accounting?

   The PR4000 supports local authentication, but most users use an authentication server. The PR4000 supports both RADIUS and TACACS protocols and inter-operates with all the popular authentication servers running in Windows, Linux and Unix platforms. The PR4000 is also RSA-certified and can support token authentication.

8. Does the PR4000 support T1 and E1 trunks? What about analog phone lines?

   The PR4000 is a digital Remote Access Server. That means that it physically connects to digital T1, J1 or E1 trunks. Each T1 or J1 trunk supports the equivalent to 23 phone lines and each E1 line supports the equivalent of 30 lines.
   T1 is used in North America, J1 is used in Japan and E1 is used in Europe and most of the other countries.
   Even though clients with analog phone lines can connect to it, the PR4000 does not support physical connections to analog phone lines (POTS).

9. What are the signaling standards supported by the PR4000?

   T1 digital trunks used for remote access can use two basic signaling types: ISDN-PRI (used in all new central offices) and CAS (R2D/MFR2) signaling (used by old phone switches).
   The PR4000 supports all ISDN switch types in use today (including the US National ISDN standard, the European ETS standard, the AT&T and DMS100 custom switches and many local variants).
   In some countries, CAS signaling R2D/MFR2 protocols are still in use. The PR4000 supports the large majority of countries using CAS, including all using signaling compatible with the ITU/T standard (most countries) and many countries using proprietary signaling schemes (including US, Brazil, Mexico, Indonesia, India, Romania).

10. Does the PR4000 support MLPPP?

    Yes, the PR4000 supports MLPPP and can inter-operate with any other MLPPP implementation. It also supports MLPPP over multiple units (Multi-chassis MLPPP). Because there is no standard for MC-MLPPP, the PR4000's can do MLPPP over multiple chassis only with other PR4000 and also with the Lucent PM3 (or Livingston PPM3).

11. Does the PR4000 use Linux? How is the configuration interface? Does it have a WEB-based interface?

    No. Cyclades is the Leader in Linux Connectivity and many of our products are designed for Linux or run embedded Linux as their OS. That is not the case of the PR4000 (which runs CyROS, the Cyclades Routing OS). The PR4000 inter-operates seamlesly not only with Linux, but also with any other OSes running TCP/IP.

    The PR4000 uses the CyROS menu interface. This is a text interface that can be used over telnet or at the console and guides you using menus (no command line interface). There is also a WEB-based tool for administration and monitoring.

    Of course, the PR4000 also supports SNMP.

12. Do I need to buy a support contract to get software updates and configuration help?

    No. Cyclades thinks you should not pay to get bug fixes. We also don’t charge you to provide improvements and additional functionality we incorporate in the standard product.The PR4000 comes with free and unlimited technical support and software updates for the life of the product.

13. Does the PR4000 support Call back and Dial out?

    Yes, the PR4000 supports both call back and dial-out functions. It can be configured to call back clients based on a fixed phone number (for security purposes) or based on PPP negotiation (for reverse charging purposes). It can also be used as a digital modem pool with an application resident in a host accessing the modems over a TCP socket connection.

14. How is the PR4000 different from other products?

    The PR4000 is the only product in the market designed for the small- and medium-sized ISP and supported by a company that is devoted to Networking. Other popular products are being discontinued or are not being developed anymore after their manufacturers (Ascend, Livingston, ACC, Bay, etc) were acquired by the large vendors (Cisco, Lucent, Ericsson, Nortel) focusing on the large telco- and enterprise market. Some other companies offer low-end RAS products similar to the PR4000, but none with the networking background and the focus on this market as Cyclades.

15. Does the PR4000 support...

    1. 56K and other modem standards? Yes, the PR4000 supports K56Flex and V.90. It also supports all the older modem standards (V.34, V.32bis, all the way down to 300bps modems).
    2. VPN, PPTP, L2TP? The PR4000 supports standard TCP/IP and therefore can transport any VPN protocol without problems and inter-operates with any VPN solution. It cannot be a VPN gateway and terminate a PPTP or L2TP tunnel.
    3. VoIP? No, the PR4000 does not support VoIP gateway functions and currently there are no plans to support it.
    4. V.110, V.120? Those are encapsulation schemes used for remote access using mobile phones (especially popular in Europe). V.110 is supported. V.120 support is planned but not available as of 02/01.
    5. ADSL clients? No. ADSL is a point-to-point technology (not switched) that requires a termination at the Central Office. The PR4000 supports only analog and digital switched calls.
    6. OSPF, BGP4? Yes. Those are routing protocols supported by the PR4000.
    7. Fax? No. While the DSP we use has fax software in it, we currently do not support fax applications on the PR4000.
    8. Linux, Windows, FreeBSD, MacOS?. Yes, the PR4000 interoperates with servers and connects to clients using any OS. We specifically test them in the lab with all OSes mentioned above.
       
    
    

16. Can the T1/E1 ports be used for routing?

Yes. While the T1/E1 ports on the PR4000 were designed primarily for access, they can also be used for channelized T1/E1 routing. That way, a PR4000 chassis (without digital modems) can be seen as a router with 2 Ethernet ports, 2 channelized T1/E1 ports and an optional Serial WAN port