 Category :: Computer Certification Articles |
Author :: Chris Bryant  |
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| Article Title :: Cisco CCNA / CCNP Home Lab Tutorial: The 2520 Router |
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| I know from experience that part of the excitement and anxiety of putting together your own CCNA / CCNP home lab is deciding what to buy! While you can make a workable home lab out of almost any combination of Cisco routers and switches, some routers are better suited for home lab work than others because they can fill multiple roles.My personal favorite is the Cisco 2520. This router has four serial interfaces, making it an ideal frame relay switch. Don't forget that just because you're using a router as a frame switch, you can still use its routing capabilities. One setup I use is to use three of the four serial interfaces for frame switching and the fourth interface as a poi (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNA Exam Tutorial: Configuring Standard Access Lists |
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| Access Control Lists (ACLs) allow a router to permit or deny packets based on a variety of criteria. The ACL is configured in global mode, but is applied at the interface level. An ACL does not take effect until it is expressly applied to an interface with the ip access-group command. Packets can be filtered as they enter or exit an interface.If a packet enters or exits an interface with an ACL applied, the packet is compared against the criteria of the ACL. If the packet matches the first line of the ACL, the appropriate “permit” or “deny” action is taken. If there is no match, the second line’s criterion is examined. Again, if there is a match, the appropriate ac (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: Configuring And Troubleshooting OSPF Virtual Links |
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| Knowing when and how to create an OSPF virtual link is an essential skill for BSCI and CCNP exam success, not to mention how important it can be on your job! As a CCNA and CCNP candidate, you know the theory of virtual links, so let's take a look at how to configure a virtual link, as well as some real-world tips that many CCNA and CCNP study guides leave out!In this configuration, no router with an interface in Area 4 has a physical interface in Area 0. This means a logical connection to Area 0, a virtual link, must be built.In the following example, R1 and R3 are adjacent and both have interfaces in Area 0. R4 has an adjacency with R3 via Area 34, but R4 has no physical in (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNA Exam Tutorial: Mapping The OSI Model To The TCPIP Model |
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| The OSI model is the model that most networking personnel are familiar with, but to earn your CCNA, you need to know the OSI model, the TCP/IP model, and how the two map to each other.The four layers of the TCP/IP architecture can be compared to certain levels of the OSI model. It’s important to know what each level of the TCP/IP protocol architecture does, and how these layers map to the OSI model.The Application Layer of the TCP/IP model performs much the same tasks as the Application, Presentation, and Session layers of the OSI model.The Transport layer in the TCP/IP architecture is similar to the Transport layer in the OSI model. This layer can use TCP or UDP (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNA Exam Tutorial: Cisco Discovery Protocol (CDP) |
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| The Cisco Discovery Protocol (CDP) sure looks simple enough, but there are quite a few details to know for success on the CCNA exam. In your CCNP studies, you'll be introduced to additional uses for CDP, but for now it's enough to know that CDP is designed to give you information regarding directly connected Cisco routers and switches.CDP runs by default between all directly connected Cisco devices. CDP is also a Cisco-proprietary protocol - if the directly connected device is not a Cisco device, you won't see the information you wanted.The basic CDP command to display information about the directly connected neighbor is "show cdp neighbor".R2#show cdp neighbor (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: Filtering BGP Updates With Prefix Lists |
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| A major part of your BSCI and CCNP exam success is mastering BGP, and that includes filtering BGP routing updates. In this tutorial, we'll take a look at how to filter BGP updates with prefix lists.R4 is advertising three networks via BGP. The downstream router R3 sees these routes and places them into its BGP table as shown below. R3 has two downstream BGP peers, R1 and R2, and is advertising itself as the next-hop IP address for all BGP routes sent to those two routers.R4(config)#router bgp 4R4(config-router)#network 21.0.0.0 mask 255.0.0.0R4(config-router)#network 22.0.0.0 mask 255.0.0.0R4(config-router)#network 23.0.0.0 mask 255.0.0.0R3#show (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: Configuring PortFast And BPDU Guard |
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| In your CCNA studies, you learned about PortFast and the trouble it can cause if configured on the wrong port! Suitable only for switch ports connected directly to a single host, PortFast allows a port running STP to go directly from blocking to forwarding mode.A Cisco router will give you a warning when you configure PortFast:SW1(config)#int fast 0/5SW1(config-if)#spanning-tree portfast%Warning: portfast should only be enabled on ports connected to a
single host. Connecting hubs, concentrators, switches, bridges, etc...
to this interface when portfast is enabled, can cause temporary
bridging loops. Use with CAUTION%Portfast has been configured o (read full article) |
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| Category :: Computer Certification Articles |
Author :: Chris Bryant |
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| Article Title :: Cisco CCNA Exam Tutorial: IGRP And Equal Cost Load Balancing |
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| To pass the CCNA exam, you've got to know the role of the bandwidth command with IGRP and EIGRP and when to use it. In this tutorial, we'll configure IGRP over a frame relay hub-and-spoke network using the following networks:R1 (the hub), R2, and R3 are running IGRP over the 172.12.123.0 /24 network. This is a T1 line.R1 and R3 are also connected on a different subnet, 172.12.13.0 /24. The bandwidth of this connection is 512 KBPS.R2 and R3 are also connected by an Ethernet segment, 172.23.0.0 /16.We'll configure IGRP on R1, R2, and R3 with the router igrp 1 command. IGRP will run on all interfaces in the 172.12.0.0 and 172.23.0.0 network.R1#conf t (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: ISIS Router Types |
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| To pass the BSCI exam and earn your CCNP, you've got to know ISIS inside and out. There are many similarities between ISIS and OSPF, but one major difference is that ISIS has three different types of routers - Level 1 (L1), Level 2 (L2), and L1/L2.L1 routers are contained in a single area, and are connected to other areas by an L1/L2 router. The L1 uses the L1/L2 router as a default gateway to reach destinations contained in other areas, much like an OSPF stub router uses the ABR as a default gateway.L1 routers have no specific routing table entries regarding any destination outside their own area; they will use an L1/L2 router as a default gateway to reach any external ne (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: BPDU Skew Detection And Cisco Switches |
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| You may look at that feature's name and think, "What is a BPDU Skew, and why do I want to detect it?" What we're actually attempting to detect are BPDUs that aren't being relayed as quickly as they should be.After the root bridge election, the root bridge transmits BPDUs, and the non-root switches relay that BPDU down the STP tree. This should happen quickly all around, since the root bridge will be sending a BPDU every two seconds by default ("hello time"), and the switches should relay the BDPUs fast enough so every switch is seeing a BPDU every two seconds.That's in a perfect world, though, and there are plenty of imperfect networks out there! You may have a busy switc (read full article) |
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