Cisco offers a password recovery technique for almost every device they have available. In this post, I’m going to cover how to complete a password recovery on a Cisco router. There are 2 things that have to be in place before a password recovery can be done. Physical access to the router A console connection […]
In most smaller networks, or networks that have a few network administrators, when you log into a Cisco device you are only prompted for a password. This will take you to the Router> prompt where more than likely you will immediately type ‘enable’ to enter into privileged exec mode, and you will be prompted with […]
Secure Shell (SSH) is a protocol that allows us to connect to devices securely by using encryption. Gone are the days were most networking engineers are happy with using plain telnet with it’s clear text transmission of data which could result in an attacker sniffing the line for usernames and passwords. Configuring SSH on a […]
DHCP (Dynamic Host Configuration Protocol) allows a server (in this scenario a Cisco router) to issue IP addresses to computers on the network dynamically. This is not a great solution for servers, which should have static IP addresses, but for client computers needing access to the network quickly and easily, this is certainly a great […]
Cisco routers use HDLC (High-Level Data Link Control protocol )as their default encapsulation protocol on serial lines. This works fine and there are no major problems with running HDLC however it lacks the troubleshooting commands that PPP (Point-to-Point Protocol) provides us. I learnt the value of PPP about 10 years back when I was installing […]
Two commands which are often confused or misunderstood, are the clock rate and bandwidth commands. In order to understand clock rate we first need to understand how the cabling works on routers. When connecting two routers together with a serial cable, one of the routers needs to host the DCE (Data Communications Equipment) side of […]
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 […]