The easiest method to backup Cisco routers and Switches would be when you are logged onto it using a tool like HyperTerminal either via telnet,ssh or via console.
For information on how to backup config on a cisco router or a switch using TFTP click here
It is always important that a copy of the config is saved elsewhere on a server to facilitate a speedy recovery should there be a catastrophy. While Cisco Routers and Switches can recover from a crash as long as the running-config is copied to the startup config. There is every reason for it to fail as it did on one of my Catalyst 3750s.
There is a lot of automated config backup solutions available for free/opensource. Its worth knowing a manual backup procedure as well.
RANCID is Really Awesome New Cisco Config Differ. AS its name implies, RANCID monitors network device configuration, including software and hardware and uses CVS (Concurrent Version System) or Subversion to maintain history of changes. RANCID is simple and is easy to use.
The same very functionality of RANCID can be used as a backup system for Network device config backup system or even a config change alert system as it can email changes from previous saved configurations. All this RANCID does by logging on to a network device using Telnet or SSH and runs various show commands to grab config changes (hardware & Software), send alert emails of any changes, format the info and commit to the CVS system.
Any software is pron to have software upgrades either to fix a bug or a Security vulnerability or even for the fact the software has reached its end of life.
While Network devices and appliances are no exception, the upgrade process requires a lot of precautions and measures are taken to ensure that the upgrade process doesn't fail or cause problems post installation. Upgrading Cisco IOS is no exception. Care has to be taken to ensure that the newer version is tested on a test bed before deploying in the production network especially if we are talking core network switches and routers.
STP Portfast is a feature in Cisco IOS which allows a switchport which is participating in STP to directly transition from Blocking mode to Forwarding mode when a device connects and the link goes up. This can improve the initial connect time and can fix some issues with Windows based devices connecting to the Active Directory domains.
STP Portfast is ideal for ports which connects directly attached devices and certainly not for the ports which connects a hub or a switch. Hence, good to set switchports that directly connect end devices on your Access switch.
DHCP, Dynamic Host Configuration Protocol is the protocol used by network devices like a PC or a printer (DHCP clients) to obtain IP Address, Default Gateway, Domain Name, DNS Servers, NetBIOS servers and more that helps the device to work properly in an IP Network.
While in an ideal scenario, most if not all organisations run the DHCP server on a Windows server or a Linux/Unix server. While this is justfiable in bigger corporate and enterprise networks, a smaller network like a branch office can be supported by a local Router, Switch or a Firewall can run a DHCP server without the need of an additional server hardware to run DHCP. Most of the routers, firewalls and some switches do have a DHCP server builtin. Most of the new Cisco Routers and Switches running Cisco IOS can run a DHCP server.
NAT, Network Address Translation in simple terms translates an IP address into another. Network Address Translation is of different types like
Static NAT (One to One)
Dynamic NAT (Many to Many)
Overloading (Many to One)
We will focus on Overloading form of NAT. This is called as Port Address Translation (PAT) or even Network Address Port Translation (NAPT). NAT Overloading translates many private IP addresses from a Local Area Network (LAN) onto a single registered legal Public IP address. Here, the source IP and the source port gets translated to the Public IP and a different source port.
Typical network configuration would be on an Internet Router which enables all the hosts in the LAN to connect to the Internet using one single Public IP address.