An
access server is an invaluable part of a Cisco home lab. Chris Bryant,
CCIE #12933, explains their importance, gives tips on purchasing one,
and gives a sample configuration.
A Cisco access server is generally the last item a CCNA or CCNP
candidate has on their mind when they're putting together a home lab.
The thinking tends to be that since this router isn't really doing
anything in the production part of your practice lab, it's not really
important.
Once you have more than two devices in your home lab, though, you'll
realize that constantly moving the console cable around from one router
to another gets very tiresome. That's what an access server does for a
home lab - it allows you to connect your PC to a single device when
working in your home lab, with no need to constantly disconnect and
reconnect the console cable. The console cable will be connected
directly to the access server, and the access server is connected to
all the other devices in your home lab. Once you start working with
one, you'll wonder how you got along without it!
The term "access server" is a little misleading. This is not a server
in the traditional sense, it's a Cisco router with asynchronous serial
ports. It is these ports that you'll use to connect to the other
devices in your home lab. Two affordable models of access servers are
Cisco 2509s and Cisco 2511s. They can be found on ebay as well as other
vendors on the Net.
You will also need an octal cable. On one end, the cable has a large
connector that will connect to the access server. The other end is
actually eight separate cables, each with RJ-45 connectors. These
connectors are numbered 1 - 8 and will be connected to the console port
on each router and switch. It is important to note the number on each
connector you're connecting to the other lab devices.
Now that you've got the physical equipment, let's take a look at a typical configuration of an access server:
no service password-encryption
no service udp-small-servers
no service tcp-small-servers
! hostname BRYANT_ADVANTAGE_AS4
no ip domain-lookup
ip host r1 2001 10.4.4.4
ip host r2 2002 10.4.4.4
ip host r3 2003 10.4.4.4
ip host sw1 2004 10.4.4.4
ip host sw2 2005 10.4.4.4
ip host FrameSwitch 2006 10.4.4.4
interface Loopback555
ip address 10.4.4.4 255.255.255.0
line con 0
exec-timeout 0 0
logging synchronous
line 1 16
no exec
transport input all
You can assign any loopback address and number here the important thing
to note is that the IP HOST table you will build constantly refers back
to the loopback address on the access server.
In this configuration, I have the octal cable's connector 1 in R1, 2 in
R2, 3 in R3, 4 in SW1, 5 in SW2, and 6 in my frame relay switch. The
number "2001" in the first line of the IP HOST table refers to that
connector. That's why it is important to note the number on a given
connector you place in the console port of a router or switch.
The asynchonous lines are identified by "line 1 16". This access server
has 16 possible connections many will just have 8, which is usually
plenty. Regardless of how many lines you have, you'll need the commands
transport input all and no exec to allow reverse telnet to work
effectively.
There's one more thing to watch out for. When you first connect to the
AS for a practice session, you will need to open the line to each
device by using the full hostname of the device as shown in the IP HOST
table. Here, you would begin by entering R1, R2, R3, SW1, SW2, and
FrameSwitch to open the line to each device. After that, you need to
enter the line number - 1, 2, 3, 4, 5, and 6. It sounds a little
confusing at first, but after just a few minutes of practice you'll be
doing it without even thinking about it.
When you are working in your home lab, you will not go from one device
to another that is, when you are done on R1 and want to configure R2,
you must go back to the access server and then to R2. The keystroke to
do this is . Again, it may sound complicated, but after a little
practice you will again do this without thinking about it.
Adding an access server to your CCNA or CCNP home lab may not be on
your mind now, but once you add a few more routers or switches to the
lab, you'll want to spend more time configuring and practicing and less
time moving a cable around. And once you get one, you'll wonder how you
did without it!
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study
Packages. Video courses and training, binary and subnetting help, and
corporate training are also available.
For a FREE copy of his latest e-books, "How To Pass The CCNA" or "How To Pass The CCNP", send a request to chris@thebryantadvantage.com today !
