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Reliable
Host?
I am sick of GoDaddy.com. They will not allow off-site MySQL administration and
do not allow modifications to the .htaccess file.
What
is a good hardware firewall?
I am running my own server in house, using linux. I need a good hardware firewall.
I know Symantec used to make a really cool firewall /vpn appliance, but I can
seem to find it anymore.
Windows
Server 2003 Active Directory/DNS/DHCP
This is going to sound rather strange, but I've got a client who has an "old"
Windows Server 2003 on its last legs (one SCSI hard drive is dead, and the other
dying in a RAID 1), and what I'd like to be able to do is use the settings for
it on the replacement server, which just came in on Monday.
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| Recent
Articles |
Passing
The CCNA and CCNP: Home Lab Shopping On Ebay
Whether you're just getting ideas for your Cisco home lab or adding to your existing
lab, ebay is a great place to get ideas for your lab as well as pick up some great
bargains. Of course, the internet being what it is ...
Cisco
CCNA / CCNP Tutorial: Home Lab Assembly Case Study
Part of your CCNA / CCNP education is deciding what network topology to use when
you're putting together your home lab. Some of you are starting with one or two routers or switches, while others are starting with more.
OSPF
E1 E2 Routes
OSPF is a major topic on both the CCNA and CCNP exams, and it's also the topic
that requires the most attention to detail. Where dynamic routing protocols such as RIP and IGRP have only one router type, a look at a Cisco routing table shows several different OSPF route types.
Wireless
Home Networking – Choosing The Right One
Are you suffering from a home wireless networking nightmare? There are so many
options. 802.11a, 802.11b, 802.11g - what is all that? All you want is to get
online on your notebook computer in your living room without tripping over wires.
Cisco
CCNA / CCNP Home Lab: Why You Need An ISDN Simulator
ISDN is a vital topic for today's CCNA and CCNP candidates, especially for the
ICND and Intro exams - you've got to know ISDN inside and out to pass those exams.
Naturally you want to include it in your home lab.
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12.07.05
Router On A Stick
 By
Chris Bryant
For CCNA and CCNP candidates, it's hard not to laugh the first time you hear the
phrase "router on a stick".
Let's face it, that's a pretty silly term. But as those who have passed the CCNA
and CCNP exams know, this is a vital exam topic that you must know how to configure
and troubleshoot.
Basic Cisco theory states that for hosts in different VLANs to communicate, a
Layer 3 device must be involved to handle the routing between the VLANs. That
device is a router, and there are special considerations that must be taken into
account for both the physical router itself and the configuration you'll be writing.
The router will be connected to a switch via a FastEthernet port (or higher).
The router port cannot be a regular Ethernet port, since the router port will
need the ability to send and receive data at the same time.
The configuration of the interface is where things get interesting. Let's say
we have two VLANs that will be using router-on-a-stick to communicate. Here is
the VLAN information:
VLAN 20: 20.20.20.0 /24
VLAN 40: 40.40.40.0 /24
The port on the switch that will be connected to the router's FastEthernet port
must be in trunking mode, and you must know the trunking protocol in use. We'll
go with the Cisco-proprietary ISL here.
The physical FE port on the router will not have an IP address. The use of router-on-a-stick
mandates the use of logical subinterfaces. While we don't have to use the VLAN
numbers for the subinterface numbers, I've found this helps you keep the interfaces
straight. One subinterface must be given an IP address in VLAN 20, and the other
will have an IP address in VLAN 40.
After creating subinterfaces fast 0.20 and fast 0.40, the config looks like this:
interface fastethernet0
no ip address
interface FastEthernet 0.20
ip address 20.20.20.1 255.255.255.0
interface FastEthernet 0.40
ip address 40.40.40.1 255.255.255.0
Believe it or not, you're almost done! Now we need the encapsulation statement
under each subinterface. The subinterface statement must reflect both the VLAN
number and the encapsulation type being used. When we're finished, the config
would look like this:
interface fastethernet0
no ip address
interface FastEthernet 0.20
ip address 20.20.20.1 255.255.255.0
encapsulation isl 20
interface FastEthernet 0.40
ip address 40.40.40.1 255.255.255.0
encapsulation isl 40
And that's it! Your hosts in VLAN 20 should now be able to communicate with hosts
in VLAN 40, and vice versa.
A couple of final troubleshooting points - the most common error with router-on-a-stick
is to put the wrong vlan number in the encapsulation statement. Also, make sure
you have configured the router's IP address in VLAN 20 as the default gateway
for hosts in VLAN 20, and do the same for VLAN 40.
I hope you've enjoyed this look at router-on-a-stick. While the name may get a
chuckle out of you, it's still used in quite a few networks out there, and knowing
how to configure and troubleshoot it will get you that much closer to earning
your CCNA and CCNP.
About the Author:
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (www.thebryantadvantage.com),
home of FREE CCNA and CCNP tutorials and The Ultimate CCNA Study Package. (CCNP
Study Packages are on the way!) Video courses and training, binary and subnetting
help, FREE tutorials, and corporate training are also available. |
