Archive for the 'CCNA (ICND2)' Category

Static NAT overloaded???

Wednesday, July 27th, 2011

So we have already looked at all 3 possible NAT configurations, however there is one more trick that is always useful to know. How to overload a Static NAT. Let’s assume the following for this example We have 2 public IP addresses ( & The IP address on the outside interface has been configured [...]

Configuring PAT on Cisco Routers (NAT Overload)

Wednesday, July 20th, 2011

PAT (Port Address Translation) is by far the most common implementation of NAT, and if you have an ADSL router at home there is a 100% chance you are using it. PAT or otherwise known as NAT overload, allows you to translate IP addresses in a many-to-one method. In my previous post on Configuring Dynamic [...]

Configuring Dynamic NAT on Cisco Routers

Friday, July 15th, 2011

In my last post Configuring Static NAT on Cisco Routers we saw how you can translate 1 IP address into another single IP address. This tutorial will cover how to translate many IP addresses into many IP addresses, otherwise referred to as many-to-many translation. Dynamic NAT allows us to translate many IP addresses into a [...]

Configuring Static NAT on Cisco Routers

Thursday, July 7th, 2011

In my previous post on NAT, I explained the difference between the 3 different types of NAT that can be configured. In this tutorial I’m going to cover the configuration steps to configure static NAT. Static NAT is a one-to-one mapping. It allows us to translate a single IP address into a different single IP [...]

NAT (Network Address Translation)

Monday, September 21st, 2009

NAT or Network Address Translation is a key function required in every organisations network. Since all organisation use RFC 1918 IP addressing, and these IP addresses are not allowed to exist on the internet, before we send packets to the internet we need to translate the internal IP address into a useable public IP address. [...]

Restricting access to VTY (Virtual Terminal Lines)

Friday, August 14th, 2009

One of the first and most important things to configure on any Cisco device after allowing telnet or SSH, is to restrict who is allowed to access the device. Of course having a password on the lines is the first step but if telnet is the method of communication, all passwords will be sent over [...]

Introduction to ACLs (Access Control List)

Thursday, August 13th, 2009

Before looking into the configuration of ACL (Access Control Lists), it’s important to get some of the concepts and understanding of how they work and what they are used for. Firstly, most people believe that ACL’s are used purely for denying or allowing traffic, although this is certainly one of the functions of a ACL [...]

Inter-VLAN Routing (Router on a Stick)

Wednesday, August 12th, 2009

In order for 2 VLANS to be able to communicate, the traffic must be routed. This can be done either by a multi-layer switch which will have routing capabilities, or the packets can be routed by a router.   As an example, I have 2 VLANS, VLAN 10 and VLAN 20 which have subnets [...]

VTP (VLAN Trunking Protocol)

Tuesday, August 11th, 2009

VTP (VLAN Trunking protocol) is a protocol used to replicate the VLAN information across switches, however there are a few things that must be made clear…   1/ VLAN information will only be sent on trunk ports 2/ Only the VLAN identity is replicated, NOT which ports are configured to use that VLAN! 3/ Maintains [...]

Concept and Configuring VLAN’S

Friday, August 7th, 2009

A VLAN is a Virtual LAN which allows us to logically separate computers on our network.   In previous years, an office would have a physical switch or hub in each office, and offices were structured around the job function. In other words, all sales people would be in the same office and would all [...]