Review of DIVA LAN ISDN Router
This article first appeared on CNet Malaysia. You can get it here
Quick Facts : Operating
system independent, 4-port 10BaseT network hub, expandable to 50
users, Console port for administrative purposes, DHCP server and DNS
relay, Full ISDN BRI compatibility, On-board STAC compression and
transparent PPTP support, Interoperable with all major switch types,
Telnet and TFTP Support, IP filtering and spoofing.
ISDN Router/Hub Combination Devices:
A Complete SOHO Solution?
It was just a week ago, that I took a
look at a DIVA ISDN device - two of them actually. The DIVA T/A and
DIVA USB. Well this time around, I got a chance to test drive their
more "business oriented" offering - the DIVA LAN. The
device is a router/ISDN based device that allows business users to
get connected in the shortest period of time with the least amount of
hassle.
Router Must-Haves
When you need to deploy an ISDN router,
you want the unit to work as advertised but, more importantly, it
must be so easy to set up that a nontechnical user can just pull it
from the box, plug it in and it's up and running.
Almost every single router on the
market right now shares common bandwidth management features such as
dial-on-demand, bandwidth-on-demand and Multilink PPP. Dial-on-demand
lets you save on ISDN connect charges by only connecting when you
need access to a resource which is not on your local network.
Bandwidth-on-demand works in conjunction with Multilink PPP to bring
up the second B channel when you reach a specified utilization level.
A new feature that many router
companies are beginning to incorporate is call Always On/Dynamic ISDN
(AO/DI). The concept of AO/DI is to make use of wasted bandwidth
found in the 16-Kbps D channel. Typically, there is about 9.6 Kbps of
this channel available for use after normal ISDN control overhead.
AO/DI uses this channel to keep a continuous link to your ISP open
for instant e-mail and, should bandwidth requirements call for it,
bring up the B channels. In areas where ISDN usage is subject to
per-minute tariffs, this helps people stay connected while keeping
costs down. The DIVA LAN is pretty much the first ISDN router I've
seen that employs this feature.
Since the world is moving quickly to
IP, things such as Dynamic Host Configuration Protocol (DHCP),
Network Address Translation (NAT) and Port Address Translation (PAT)
are necessary features of your ISDN router. DHCP helps manage your IP
addresses for your client PCs on your network. This eliminates the
need to visit each computer and give it an IP address, gate-way
address and subnet mask. Depending on the vendor, the DHCP server in
the router might only handle 25 clients or else it may take care of
multiple Class-C networks.
NAT and PAT are very important. To keep
your network clients secure, you want to use a private IP addressing
scheme. NAT maps your local private IP addresses to a single IP
address assigned by your ISP. This does two things: it lets you
connect more than one PC while only using a single logon, which saves
on user accounts, and it translates your hidden addresses to a valid
one.
PAT maps TCP-based and User Datagram
Protocol (UDP)-based applications, such as Microsoft NetMeeting and
Real Networks RealPlayer, through the router. Not all implementations
of PAT are alike, and many routers only offer limited PAT support.
Some UDP-based applications open a number of different IP ports, and
it is difficult for the routers PAT server to know what port number
is for which local client.
VPN anyone?
Between the "work-in-progress"
IPSec specification and Microsoft's Point-to-Point Tunneling Protocol
(PPTP), having access to VPN capabilities means you have the ability
to make secure connections to your corporate network. There are
routers on the market that actually terminate the VPN session while
other support PPTP passthrough.
PPTP passthrough enables you to create
a tunnel through the router out to a Windows NT RRAS (Routing and
Remote Access Service) server to reach resources on the corporate
LAN. There is one advantage that PPTP offers vs. a tunnel at the
router. With PPTP passthrough, only the client PC that needs to
tunnel into the corporate LAN has access to those resources behind
the NT RRAS server. This can help you manage remote users' ability to
get to secure resources.
The device
Since the Diva is an "IP-only"
router, you will find all of the necessary services to fully handle
IP traffic. Color-coded cables help make setup easier for
nontechnical users, and the configuration utility helps you check for
and correct TCP/IP settings on your PC.
One major criteria I always look at is
with regards to ease of use and configuration. The Diva gets high
marks because of its extensive configuration and monitoring features.
You start the setup of the Diva from a Windows-based utility and
complete the process using your Web browser. During the initial phase
of the setup, the Eicon utility checks your PC to make sure that
TCP/IP is installed and working. If it finds a problem, it prompts
you for corrective measures. If you're installing the device on a
non-windows based network, you can use your web browser for setting
up the device - however you'll need to setup one machine on the
network to make use of the 192.168.1.x (Class C) network. The IP of
the Diva LAN is 192,168.1.1 by default with no password. Make sure
you remember to set a password once you log in.
However, if you're on a non-windows
network, you won't be able to take advantage of the Diva's utilities
which really excel in their monitoring and reporting capabilities.
From the Diva Modem Monitor icon docked on the System Tray, you can
configure your LAN ISDN Modem, view its log file, and also back up
and restore configurations. You can also check the Diva's status via
your Web browser. Other routers provide much of the same information
but Eicon simplified the task of working with your router by
consolidating everything into a single icon.
The Diva's implementation of DHCP can
handle only 50 entries. This means that for more than 50 clients, you
will have to manually handle IP address distribution. Along with DHCP
you'll get DNS relay for domain name resolution and NAT service which
is very solid and can handle streaming multimedia sessions such as
Microsoft's NetMeeting.
The Diva comes with a four-port
Ethernet hub in the router. You also get an RJ-45 console port as
well as an ISDN "U" interface port. Using the two POTS
(Plain Old Telephone Service) ports, you get analog call handling,
including call forwarding, caller ID and call waiting.
How We Tested
Our test-bed included three separate
machines. One Pentium II 400MHz (128MB RAM) based machine, an old
Pentium 133 (64MB RAM), and a really old 486 notebook. The Pentium II
400 was running FreeBSD (a UNIX derivative) while the Pentium 133 and
notebook were running Red Hat 6.1 and Windows 95 respectively.
To test raw throughput, I downloaded a
single noncompressible 130K file from a Web site over an ISDN line.
We used a noncompressible file as this is the type of file typically
downloaded from the Web. Compression comes into play in some
circumstances, but most files users download have already been
compressed at the site.
To test how the device allocated
bandwidth between the two B-channels, I downloaded the same file to
two systems simultaneously. The FTP (File Transfer Protocol) test
showed that all the device split the data flow to about a 60/40 ratio
between any two clients. The test also demonstrated that the DIVA
LAN implements MultiLink PPP (MP) well, providing a single client
with over 100 Kbps of bandwidth, on the average.
Though most ISDN routers these days
will provide throughput speeds from 110 to 120 Kbps, the actual speed
at which you download files depends on their size and number. When
you download a file, the network device interacts by opening and
closing TCP connections, each instance of which adds a layer of
overhead to your connection. Also contributing to overhead is the
routers translation of the registered IP address to a client's NAT
address. In general downloading one large file allows the router to
sustain a higher throughput than downloading several small ones.
On the whole the Diva offers a good
combination of features, including an easy-to-use Web/applet-based
installation and management utility, NAT, DHCP services and link
optimization.
1.) Daemon
processes - psyops
2.)Analysis
: Implications of Internet Growth - CptZZap
3.)The Art of
IRC - JesterS
4.)Network
Stacks & TCP/IP - Liquid Sphear
5.)Basics of
Internet Investigations - madirish
6.)Proliferation of
the Internet
7.)Having fun
with system.ini - xearthed
8.)A look into
VPNs and setting one up - L33tdawg
9.)Review of
DIVA LAN ISDN Router - L33tdawg
10.)Strategies
for Tomorrows War - Cpt ZZap
