OSPF (Open Shortest Path First) is an industry open standard supported by almost every router on the planet. OSPF is a classless routing protocol so subnetmask values are sent in the update and it supports CIDR. OSPF does not send periodic updates and is designed to only send updates when something has changed or […]
EIGRP (Enhanced Inter-Gateway Routing Protocol) is one of the fastest most reliable routing protocols available today, but it’s drawback is that it’s a Cisco proprietary protocol which means you either need a network that is running 100% Cisco, or have devices that support EIGRP in your network. EIGRP is a classless routing protocol so […]
RIP (Routing Information Protocol) was one of the first routing protocols that hit the market, and still one of the easiest to configure. RIPv1 is a classfull routing protocol and does not support VLSM’s or CIDR values and sends it’s updates as a broadcast message with a destination address of 255.255.255.255 RIPv2 supports […]
In yesterday’s post ‘Static Routing’ we saw that we needed to create a static route to allow the Cisco router “AOIP.ORG” to ping “R2”. The static route that we created was ‘ip route 10.0.1.0 255.255.255.0 192.168.1.1’ and ping was successful to the IP address 10.0.1.2 (R2’s Serial interface). The problem with that configuration was that […]
A router by default only knows about networks that are directly connected to it. If a router is not directly connected to the final destination subnet, then the router needs to learn, or be told how to get to that destination. Learning routes can take place through the use of routing protocols, however in […]
One of the first steps in troubleshooting a network, is to identify if the lines (links) are operational. On a Cisco router, the quickest way to see all lines as well as their status is by using the “show ip interface brief” command. In the live demo below, you will see that I have […]
In order to set up an IP address on an interface, we need to be in the interface level of the command line. This is a level within the global configuration level. From global configuration mode, we can enter the ‘interface serial 1/0’ command. If you are unsure of what interfaces are on the router, […]
Every Cisco device has 2 sets of configurations. On routers and switches these configurations are called ‘running-config’ and ‘startup-config’ When you make any changed on a router or switch, the change applies to the running-configuration and will affect the router or switch with immediate effect. However, if the device is reloaded for whatever reason, all […]
It is advisable that on all your devices in your network, you have a disclaimer or message that appears when someone connects to your device. There have been many cases over the years where a hacker has gained access, been caught, and got away with it since there was nothing in place informing that they […]
Using the Pipe ‘|’ is by far one of the most important things you can learn on a Cisco device. I never really appreciated this command when I started out in Cisco, as it seemed to take me longer to use it, and I didn’t get to see what I was looking for. In hind […]
One of the most annoying things I kept doing when I started out in Cisco, was constantly typing ‘show’ commands when in the wrong level of the configuration. By default, Cisco only allows you to do a ‘show’ command when you are in privileged mode (AOIP.ORG#). This can be frustrating when you are multiple levels […]
By default a Cisco device does not have any passwords on it, so access to the console is open by default, and anyone connecting to the device is able to access privileged mode (enable mode). This of course is a security risk and one of the first things that should be done with a new […]