Cisco IOS 2 - IOS version, upgrade and backup

Types of Switches

Cisco offers a wide range of switches, primarily targeting medium and large enterprises. The switches are named Catalyst and come in several basic series. The main distinction is based on the layer they operate on - primarily Layer 2 of the OSI model (e.g., C2960) and Layer 3 of the OSI model (e.g., C3750), and whether they are modular (C4500 and C6500).

The switch designation indicates a range of its features. The designation might look like C3750G-24PS. Some features are specific to the given model, but many are general. The name consists of main parameters, a dash, and additional parameters.

• C for Catalyst
• 3750 indicates the model series
• G indicates Gigabit ports
• 24 indicates the number of ports (excluding uplinks)
• After the number of ports, there are several options:
  • PS - powered ports (Power over Ethernet)
  • TT - uplinks are metallic RJ45 ports
  • TC - uplinks are SFP modules
  • FS - all ports are optical
  • S - all ports are SFP

There are other options, usually specific to a certain model. Similarly, the number and type of uplink ports depend on the final designation and model.

Downloading IOS

IOS can be downloaded from Cisco's Download Center. However, an account with sufficient permissions is required. Common switches are in the Switches Software - LAN Switches category. Under each series, there is a list of individual models, but the IOS is usually the same for the entire series.

For certain switches and a specific version of IOS, there are usually several software variants available for download.

Types of IOS

The IOS operating system is stored in an image file with the bin extension. A version with a web interface, which has the tar extension, can also be downloaded. This archive contains the bin file plus an html directory. The version with a web interface is labeled WITH WEB BASED DEV MGR.

Then we can choose a version with or without encryption W/O CRYPTO (does not include SSL, SSH, and SNMPv3).

Finally, it is determined what functions are included in the IOS. A specific physical switch can gain higher functionality only by purchasing a higher version of IOS. Previously, they were divided only into Standard Image and Advanced Image, but now there are many versions. Certain versions exist only for specific switches.

For Layer 2 switches, only the LAN BASE version of IOS is available, with basic network services. For Layer 3 switches, we have IP BASE - basic, IP SERVICES, ADVANCED IP SERVICES. There are also several special versions. A higher version always includes everything in the lower version.

• Layer 2 Base - L2, 802.1x, 802.3ad, 802.1s, 802.w, EtherChannel, 802.1d, Port Security, Smart Ports, SSH, etc.
• LAN Base - ACL, QoS, Enhanced 802.1x, AutoQoS, AutoSecure, etc.
• IP Base - L3, RIP, HSRP/VRRP, StackWise, GRE EIGRP STUB, WCCP, etc.
• IP Services - EIGRP, OSPF, BGP, GLBP, QoS, High Availability, NAT, nBAR, VRF-lite, Multicast, etc.
• Advanced IP Services - IS-IS, MPLS, L2/L3, VPNs, IPv6, Mobile Support, IP SLAs, etc.

Backing Up IOS from the Switch

To copy data to/from the switch, a standard TFTP server is used. We can use, for example, TFTPD32, which we run on the computer from which we manage the switch.

We connect to the switch and copy the current IOS as follows.

SWITCH#show version 					// display version information
SWITCH#show flash 					// display contents
SWITCH#cd c3750-ipbase-mz.122-25.SEB4 			// sometimes we need to go to a subdirectory
SWITCH#copy flash tftp 					// start copying 
Source filename []?c3750-ipbase-mz.122-25.SEB4.bin 	// name of the file being transferred
Address or name of remote host []?192.168.190.12 	// address of the TFTP server
Destination filename [c3750-ipbase-mz.122-25.SEB4.bin]?	// if we do not want to change the target name, press ENTER

Backing Up Configuration

We can back up the configuration in the same way as backing up IOS, only changing the name of the copied file. We can copy the running-config, startup-config, or the file where the startup-config is stored.

SWITCH#copy running-config tftp  

A more convenient way to back up the configuration is provided by the Cisco Network Assistant program. In the menu, select Maintenance - Configuration Archive.

The startup configuration is stored in the flash:config.text file.

VLAN information is stored in the flash:vlan.dat file.

Upgrading IOS

To upgrade IOS, it is necessary to copy the new image and all necessary files to the switch's Flash memory and restart it. Theoretically, we can have multiple versions of IOS stored on the switch if we have enough space. If there is not enough space on the switch, we must first delete the old image (the running system is in RAM).

SWITCH#del c3750-ipbase-mz.122-25.SEB4 	// delete the file

An easier way is to use the Cisco Network Assistant. In the menu, select Maintenance - Software Upgrade and the program will do everything automatically. It will verify the file, extract the tar archive, copy all necessary files, and restart the switch.

The second option is to do everything manually. Copy the files similarly to backing up IOS. Then initiate the switch restart.

SWITCH#reload  	// restart the switch