Networks Articles

Computers » Networks | By Chris Bryant @ Friday, 9th June 2006 @ 7:58 AM

One of the first things you learned about Frame is that the LMI also serves as a keepalive, or a heartbeat - and if three consecutive LMIs are missed, the line protocol goes down. There\'s a limitation to LMI as a keepalive, though. The LMI is exchanged only between the DTE and the closest DCE. The LMI is therefore a local keepalive that does not reflect any possible issues on the remote end of the virtual circuit. Taking the LMI concept to the next logical level, Frame Relay End... more...

Computers » Networks | By Chris Bryant @ Thursday, 18th May 2006 @ 1:38 PM

EIGRP is a major subject of the CCNA exam, and Cisco goes into even more detail with EIGRP on your CCNP exams. Part of that detail is the purpose and configuration of EIGRP stub routers. A problem with EIGRP comes in when a successor is lost and there is no feasible successor. DUAL doesn\'t give up that easily, though. DUAL will mark the route as Active, indicating that the route is being calculated and cannot be used to route data, and will send out a Query message. ... more...

Computers » Networks | By Chris Bryant @ Thursday, 18th May 2006 @ 1:30 PM

To pass your CCNA exam and earn this coveted certification, you must understand the details of port-based authentication. This knowledge has a great deal of value in production networks as well, since this authentication scheme is regularly implemented. Let\'s take a look at this particular CCNA skill. Consider a situation where you have a server that will be connected to your switch, and you want the port to shut down if a device with a different MAC address that that of the switc... more...

Computers » Networks | By Chris Bryant @ Tuesday, 16th May 2006 @ 8:56 AM

To earn your Cisco CCNA certification and pass the BSCI CCNP exam, you have to know your protocol basics like the back of your hand! To help you review these important concepts, here\'s a quick look at the basics of RIPv1, RIPv2, IGRP, and EIGRP. RIPv1: Broadcasts updates every 30 seconds to the address 255.255.255.255. RIPv1 is a classful protocol, and it does not recognize VLSM, nor does it carry subnet masking information in its routing updates. Update contains entire RIP rout... more...

Computers » Networks | By Chris Bryant @ Thursday, 11th May 2006 @ 9:55 AM

To earn your CCNA or CCNP certification, you\'ve got to understand the basics of trunking. This isn\'t just a CCNA topic - you must have an advanced understanding of trunking and etherchannels to pass the BCMSN exam and earn your CCNP as well. Before we address those advanced topics, though, you need to master the fundamentals! A trunk allows inter-VLAN traffic to flow between directly connected switches. By default, a trunk port is a member of all VLANs, so traffic for any a... more...

Computers » Networks | By Chris Bryant @ Thursday, 11th May 2006 @ 9:55 AM

Earning your CCNP certification and passing the BSCI exam depends on knowing the details of many Cisco technologies, ISIS chief among them. To help you prepare for exam success, here\'s a list of ISIS terminology and basic concepts that will help you pass this tough exam. Enjoy! ISIS Terms: Domain: section of the network under common administrative control Area: logical segment of the network composed of contiguous routers and their data links Intermediate System... more...

Computers » Networks | By Chris Bryant @ Tuesday, 9th May 2006 @ 2:51 PM

Like TCP, BGP is connection-oriented. An underlying connection between two BGP speakers is established before any routing information is exchanged. This connection takes place on TCP port 179. As with EIGRP and OSPF, keepalive messages are sent out by the BGP speakers in order to keep this relationship alive. Once the connection is established, the BGP speakers exchange routes and synchronize their tables. After this initial exchange, a BGP speaker will only send further updates upon... more...

Computers » Networks | By Chris Bryant @ Tuesday, 9th May 2006 @ 12:43 PM

When you\'re working on your BCMSN exam on your way to CCNP certification, you\'ll read at length about how Cisco routers and multilayer switches can work to provide router redundancy - but there\'s another helpful service, Server Load Balancing, that does the same for servers. While HSRP, VRRP, and CLBP all represent multiple physical routers to hosts as a single virtual router, SLB represents multiple physical servers to hosts as a single virtual server. In the following ... more...

Computers » Networks | By Chris Bryant @ Tuesday, 9th May 2006 @ 12:10 PM

Imagine this. You have an appointment with a client to work on a server or router install. A few minutes before you\'re scheduled to be there, you decide there\'s something really good on TV you\'d like to watch. Or you decide to go to the gym, or play a game, or do anything else except go see the client. Even if you weren\'t going to get fired for not showing up, it\'s certainly unfair to the client. You\'ve got a professional obligation, and you shou... more...

Computers » Networks | By Chris Bryant @ Monday, 8th May 2006 @ 2:04 PM

Part of studying for CCNA exam success is keeping all these new commands straight in your head! And let\'s face it, there are a lot of commands you need to know in order to pass the CCNA exam and earn that certification. Here\'s a review of some very important distance vector and static routing commands you need to know, along with their proper usage and console output. Bandwidth IGRP makes a default assumption that any Serial interface running IGRP is connected to a T1 line... more...