In this article, we’ll configure the internetwork using five routers connected together but we are not going to add IPv6 on the 871W router or to the LAN and WLAN networks connected to the R1, R2, and R3 routers, to keep things simple and easier to understand. So let’s get started by adding IPv6 to … Read more
We certainly have talked a lot about how IPv6 works and how we can configure it to work on our networks, but what is doing that going to cost us? And how much work is it really going to take? Good questions for sure, but the answers to them won’t be the same for everyone. … Read more
It’s time to explore the finer points of IPv6. A great place to start is by showing you how to address a host and what gives it the ability to find other hosts and resources on a network. We’ll also demonstrate a device’s ability to automatically address itself something called stateless autoconfiguration, plus another type … Read more
This article introduces you to the next generation of TCP/IP: IP version 6 (IPv6). Because of the many deficiencies found in IPv4, as well as the poor scalability for hierarchical addressing in IPv4, IPv6 was developed to meet the rapidly growing needs of small companies, corporations, and the explosive growth of the internet, especially in … Read more
Frame relay is still one of the most popular WAN services deployed over the past decade, and there’s a good reason for this cost. And it’s a rare network design or designer that has the privilege to ignore that all-important cost factor! By default, frame relay is classified as a non-broadcast multi-access (NBMA) network, meaning … Read more
Link control protocol (LCP) offers different PPP encapsulation options, including the following: Authentication: This option tells the calling side of the link to send information that can identify the user. The two methods are PAP and CHAP. Compression: This is used to increase the throughput of PPP connections by compressing the data or payload prior … Read more
As you can imagine, there are a few things that you need to know before connecting your WAN in order to make sure everything goes well. For starters, you have to understand the kind of WAN physical layer implementation that cisco provides as well as ensure that you’re familiar with the various types of WAN … Read more
So what, exactly, is it makes something a wide area network (WAN) instead of a local area network (LAN)? well, there’s obviously the distance thing, but these days, wireless LANs can cover some serious turf. What about bandwidth? Well, here again, some really big pipes can be had for a price in many places, so … Read more
As we have an article for the overview of the wireless security considerations, let’s talk about planning to implement wireless technology. There’s much more to planning a wireless LAN deployment than putting a few wireless access points in place. You need to understand how the topology, distance, and placement of the wireless access points can … Read more
Understanding the threats Introducing wireless networking into your organization opens the door to three new types of attacks on your network: war driving, direct hacking, and employee ignorance. Let us explain each of these in detail. War driving You know you’ve entered a new realm of network security when “driving” becomes one of the intrusion … Read more
Now that you have a foundational understanding of RF signals, we can move to the 802.11 standards. When many network administrators hear of 802.11 technology, their mind immediately equates this with the three or four popular wireless networking standards: 802.11a, 802.11b, 802.11g, and the standard 802.11n. however, 802.11 describes much more than this when dealing … Read more
The funny thing about wireless LAN (WLANs) is that the topology was just so cool that network administrators started deploying it and making up the business case as they went along. Wireless networks were a new way of looking at infrastructure, and within a few years of mainstream deployment, the applications that used this infrastructure … Read more
We can still remember the very first time we saw Network Address Translation (NAT) in action. “This is the most amazing thing we have ever seen,” we said, with the same awestruck feeling as the first time you walk up and look over the Grand Canyon. Okay, perhaps it wasn’t that fantastic, but at the … Read more
You’ve got to have the Cisco IOS firewall set in the IOS to make use of Context-based Access control (CBAC), and the funny thing is, it’s rare to hear someone even Cisco differentiate between the two. People usually just refer to the Cisco IOS firewall and leave it at that. But what is it? Well, … Read more
In this article, we are going to show you some more advanced ways to use access lists. Most of the advanced access-list topics are beyond the objectives of this CCNA course, so we’ll just discuss them briefly and you can find more information on the Cisco website if you are interested. However, with that said, … Read more
In the standard IP access list example, you can notice how you have to block all access from the Sales LAN to the finance department. What if you needed sales to gain access to a certain server on the finance LAN but not to other network services, for security reasons? With the standard IP access … Read more
Standard IP access lists filter network traffic by examining the source IP address in a packet. You create a standard IP access list by using the access-list numbers 19 or 13001999 (expanded range). Access list types are generally differentiated using a number. Based on the numbers used when the access list is created, the router … Read more
An Access list is essentially a list of conditions that categorize packets. They can really help when you need to exercise control over network traffic. An access list would be your tool of choice for decision making in these situations. One of the most common and easiest to understand uses of access lists is filtering … Read more
All Cisco switches are configured to be VTP servers by default. To configure VTP, first, you have to configure the domain name you want to use. And of course, once you configured the VTP information on a switch, you need to verify it. When you create the VTP domain, you have a bunch of options, … Read more
The voice VLAN feature enables access ports to carry IP voice traffic from an IP phone. When a switch is connected to a Cisco IP phone, the IP phone sends voice traffic with Layer 3 precedence and Layer 2 class of service (CoS) values, which are both set to 5 for voice traffic; all other … Read more
By default, only hosts that are members of the same VLAN can communicate. To change this and allow inter-VLAN communication, you need a router or a layer 3 switch. I’m going to start with the router approach. To support ISL or 802.1Q routing on a Fast Ethernet interface, the router’s interface is divided into logical … Read more
It may come as surprise to you, but configuring VLANs is actually pretty easy. Figuring out which users you want in each VLAN is not; it’s extremely time-consuming. But once you’ve decided on the number of VLANs you want to create and established which users you want to belong to each one, it’ time to … Read more
Most of the time, VLANs are created by a sys admin who proceeds to assign switch ports to each VLAN. VLANs of this type are known as static VLANs. If you don’t mind doing a little more work when you begin this process, assign all the host devices hardware addresses into a database so your … Read more
The following figure shows how layer 2 switched networks are typically designed as flat networks. With this configuration, every broadcast packet transmitted is seen by every device on the network regardless of whether the device needs to receive that data or not. By default, routers allow broadcasts to occur only within the originating network, while … Read more
As always, when troubleshooting connectivity issues, use a layered approach and eliminate possibilities at each layer to home in on the possible cause of the problem. Over time, you will begin to develop a sixth sense about these problems and decrease the amount of effort it takes to accurately pinpoint a connectivity problem. In the … Read more
The 802.1d spanning tree protocol was created with very few design flaws; however, as with most great things, there is always room for improvement. The biggest grievance the networking community had with spanning tree protocol was the slow convergence when a topology change occurred in the network. Recall that it could take up to 30 … Read more
Catalyst switches, for the most part, are designed so that the default state of the switch allows for basic layer 2 functionality without requiring any configuration from the administrator. For example, the physical interfaces on the switch are already enabled, which means that you can plug a cable in the switch and the interface operates … Read more
We already have an article “Datalink networking concepts”, that you can use bridges and switches to segment a LAN into smaller collision domains. This article looks in close detail at the operations of bridges and switches. Specifically, you will investigate the transparent functionality that occurs when a switch is building and utilizing its frame forwarding … Read more
One of the greatest aspects of EIGRP is that you get all this advanced functionality with minimal configuration effort. EIGRP essentially follows the same configuration guidelines as RIPv2. Namely, it must advertise directly connected networks. Because EIGRP is also classful by default, the networks configured must be at a default classful boundary. A key element … Read more
Balanced hybrid routing protocols are sometimes called advanced distance vector routing protocols. The rationale behind this logic is that these routing protocols use similar metrics and have a maximum hop count as distance vector routing protocols. However, balanced hybrid routing protocols discover neighbors and put them in a neighbor table before exchanging routing information, as … Read more