 Category :: Computer Certification Articles |
Author :: Chris Bryant  |
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| Article Title :: Cisco CCNA Certification Exam Tutorial: The OSPF RID |
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| OSPF is a major topic on your CCNA exam, as well it should be. OSPF is a widely-used WAN protocol, and you need to learn the fundamentals before moving on to more complicated configurations. One such detail is the OSPF Router ID, or RID.The RID is the dotted decimal value by which other OSPF routers will identify a given OSPF router. There are some interesting defaults for this value, and a command you should know to hardcode the RID. You had also better know what has to happen for this command to take effect, so let's take a more detailed look at the OSPF RID.In this example, R1 has an adjacency with R2 and R3 over the 172.12.123.0/24 frame network. R1 is the hub, with R2 a (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNP Certification / BSCI Exam Tutorial: ISIS Hellos And Adjacencies |
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| In my last ISIS tutorial, I mentioned that while ISIS and OSPF are both link state protocols, their actual operation differs greatly. To pass the BSCI exam and earn your CCNP, you'll need to know these differences! Today, we'll take a look at ISIS Hello types and the adjacency types that form through the use of these Hellos.Hello packets have been mentioned several times with ISIS, and with good reason. Hello packets are the heartbeat of OSPF and ISIS when heartbeats are no longer heard from a neighbor, that adjacency will be dropped. A major difference between OSPF and ISIS is that OSPF has one type of Hello packet, where ISIS actually has three!An ES Hello (ESH) is send by (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNP Certification / BCMSN Exam Tutorial: Uplinkfast |
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| You remember from your CCNA studies that when a port goes through the transition from blocking to forwarding, you're looking at a 50-second delay before that port can actually begin forwarding frames. Configuring a port with PortFast is one way to get around that, but again, you can only use it when a single host device is found off the port. What if the device connected to a port is another switch?A switch can be connected to two other switches, giving that local switch a redundant path to the root bridge, and that's great - we always want a backup plan! However, STP will only allow one path to be available, but if the available path to the root switch goes down, there will be (read full article) |
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| Category :: Computer Certification Articles |
Author :: Ben Sikes |
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| Article Title :: Webroot Window Washer |
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| For anyone concerned about what is left on their PC after using the Internet, Webroot Window Washer can set the mind at ease.
Window Washer wipes away all traces of past PC use. It not only removes Internet history, but also previously deleted files that may still have a presence on the hard disk. A quick cycle of Window Washer can:
• clear Internet history, address bar and cache
• delete selected cookies
• overwrite deleted files
• shred folders with one-click
• provide protection against deleting important files
• schedule washes
• clear unused disk space to ensure faster, (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant, CCIE #12933 |
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| Article Title :: CCNP Certification / BCMSN Exam Tutorial: Getting Started With HSRP |
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| Defined in RFC 2281, HSRP is a Cisco-proprietary protocol in which routers are put into an HSRP router group. Along with dynamic routing protocols and STP, HSRP is considered a high-availability network service, since all three have an almost immediate cutover to a secondary path when the primary path is unavailable.
One of the routers will be selected as the primary ("Active", in HSRP terminology), and that primary will handle the routing while the other routers are in standby, ready to handle the load if the primary router becomes unavailable. In this fashion, HSRP ensures a high network uptime, since it routes IP traffic without relying on a single router.
The h (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant, CCIE #12933 |
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| Article Title :: CCNP Certification / BSCI Exam Tutorial: EIGRP Stuck-In-Active Routes |
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| Passing the BSCI exam and earning your CCNP is all about knowing the details, and when it comes to EIGRP SIA routes, there are plenty of details to know. A quick check in a search engine for "troubleshoot SIA" will bring up quite a few matches. Troubleshooting SIA routes is very challengin in that there's no one reason they occur.
View the EIGRP topology table with the show ip eigrp topology command, and you'll see a code next to every successor and feasible successor. A popular misconception is that we want these routes to have an "A" next to them - so they're active. That's what we want, right? Active routes sound good, right?
Well, they sound good, but they're no (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant, CCIE #12933 |
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| Article Title :: Cisco CCNA Certification Exam Tutorial: Access List Details You Must Know! |
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| To pass the CCNA exam, you have to be able to write and troubleshoot access lists. As you climb the ladder toward the CCNP and CCIE, you'll see more and more uses for ACLs. Therefore, you had better know the basics!
The use of "host" and "any" confuses some newcomers to ACLs, so let's take a look at that first.
It is acceptable to configure a wildcard mask of all ones or all zeroes. A wildcard mask of 0.0.0.0 means the address specified in the ACL line must be matched exactly a wildcard mask of 255.255.255.255 means that all addresses will match the line.
Wildcard masks have the option of using the word host to represent a wildcard mask of 0.0.0.0. Con (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNA Exam Tutorial: Split Horizon And Hub-And-Spoke Networks |
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| For CCNA exam success, you had better know what split horizon is, how to turn it off, and when to turn it off. Knowing when to turn split horizon off is also important in production networks, because it can cause a hub-and-spoke network to have incomplete routing tables on the spokes.Split horizon exists for a very good reason - routing loop prevention. The rule of split horizon states that a router cannot send an advertisement for a route out the same interface that it came in on. Split horizon is on by default on all interfaces running RIP, IGRP, and EIGRP.In this CCNA tutorial, R1 will serve, as the hub and R2 and R3 will be the spokes. We'll first configure EIGRP ove (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNP / BSCI Exam Tutorial: The Passive Interface Command And OSPF |
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| To pass the BSCI exam and become a CCNP, you have to be aware of the proper use of passive interfaces. You learned about passive interfaces in your CCNA studies, but here we’ll review the basic concept and clear up one misconception regarding passive interfaces and OSPF.Configuring an interface as passive will still allow the interface to receive routing updates, but the interface will no longer transmit them. While the command itself would make you think this command will be applied at the interface level, that is not the case. Below, we’ll configure ethernet0 as a RIP passive interface.R1(config)#router ripR1(config-router)#passive-interface ethernet0E (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNP / BCMSN Exam Tutorial: The Core Layer Of Cisco's Three-Layer Model |
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| In this section, you're going to be reintroduced to a networking model you first saw in your CCNA studies. No, it's not the OSI model or the TCP/IP model - it's the Cisco Three-Layer Hierarchical Model. Let's face it, just about all you had to do for the CCNA was memorize the three layers and the order they were found in that model, but the stakes are raised here in your CCNP studies. You need to know what each layer does, and what each layer should not be doing. This is vital information for your real-world network career as well, so let's get started with a review of the Cisco three-layer model, and then we'll take a look at each layer's tasks. Most of the considerations at each lay (read full article) |
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