GNS3 offers multiple ways to emulate IOS. For older images, we use and maintain Dynamips; an emulator dedicated to emulate some Cisco hardware. Dynamips can run unmodified IOS images. In the new GNS3 1.4, there is a way to run a second category of switches and routers. These are classified as Routing and Switching virtual machines (or R+Svms) for short. What are the differences? Here are the major differences:
IOS images are usually run in Dynamips however R+Svms are housed in a virtual machine.
IOS images are lower in cpu and memory so you can fit more of them in one topology.
R+Svms are all vendor Routing and Switching images that are larger in size but can be imported into GNS3 for real world network emulation.
c1700series
Where do I get IOS images? One of the most common questions asked in the GNS3 forums is “Where do I get Cisco IOS images”?
Availability
Due to these platforms hitting End of Sale, End of Life, and End of Support status, the images are no longer available for download from Cisco’s support sections. Currently, the c7200 images are the only ones still available for download for those with a support contract.
IOS 15.x
Only the c7200 series get newer IOS 15 images. All other platforms are now end-of-life and only support IOS 12.4. Please note that the IOSv appliance is based on IOS 15 and there are IOU (IOS on UNIX) images with IOS 15.
Should I use a mainline and technology train image?
You will find the technology train images to contain the newest features but it may also contain the most bugs. We recommend Mainline over Technology train if you are interested on stability without the need of new features.Please see Cisco IOS Versions and Naming for more information.
Minimum memory
The minimum RAM is the amount of memory needed for IOS to work at maximum capacity with most feature configured and activated. From experience you can usually use a bit less RAM just fine.
Recommended images
We really recommend using c3640, c3660, c3725, c3745 and c7200 IOS images listed below, they have proven to be the most stable in GNS3 provided you use the right amount of RAM and Idle-PC value.
Idle-PC value
This settings will help Dynamips to consume less CPU. It’s specific to each different IOS image.
1700s have 1 FastEthernet fixed port (C1700-MB-1ETH) on its motherboard, 2 subslots for WICs (maximum of 2 Ethernet ports or 4 serial ports), and no Network Module slots. Note that interfaces do not use a slot designation (e.g. “f0”)
2600s have one or two Ethernet or FastEthernet interfaces on its motherboard, 3 subslots for WICs (maximum of 6 serial ports) and 1 Network Module slot (maximum of 4 Ethernet ports or 16 FastEthernet ports).
The c3620 supports up to 2 Network Modules (maximum of 8 Ethernet ports, 32 FastEthernet ports or 8 serial ports). Note that tt shouldn’t be used since the latest available IOS image is very old.
IOS version 12.2.26c
File name: c3620-a3jk8s-mz.122-26c.bin
MD5: dd34b958ad362ef54ba48b187f4c97b4
Minimum RAM: 64MB
Proposed idle-PC value: 0x603a8bac
The c3640 supports up to 4 Network Modules (maximum of 16 Ethernet ports, 32 FastEthernet ports or 16 serial ports).
IOS version 12.4.25d (Mainline)
File name: c3640-a3js-mz.124-25d.bin
MD5: db9f63ca1b46d18fb835496bfffe608a
Minimum RAM: 128MB
Proposed idle-PC value: 0x6050b114
The c3660 has 2 FastEthernet fixed ports (Leopard-2FE) and supports up to 6 Network Modules (maximum of 24 Ethernet ports, 32 FastEthernet ports or 24 serial ports).
IOS version 12.4.25d (Mainline)
File name: c3660-a3jk9s-mz.124-25d.bin
MD5: 4ac7e947f13c189d746149dc74992890
Minimum RAM: 192MB
Proposed idle-PC value: 0x606071f8
IOS version 12.4.15T14 (Technology train)
File name: c3660-a3jk9s-mz.124-15.T14.bin
MD5: 39950b7a563aa08e94a168260409f1e6
Minimum RAM: 256MB
Proposed idle-PC value: 0x6076e0b4
The c2691 has 2 FastEthernet interfaces its motherboard (GT96100-FE), 3 subslots for WICs (maximum of 6 serial ports) and 1 Network Module slot (maximum of 16 FastEthernet ports or 4 serial ports).
The c3725 has 2 FastEthernet interfaces on its motherboard (GT96100-FE), 3 subslots for WICs (maximum of 6 serial ports) and 2 Network Module slots (maximum of 32 FastEthernet ports or 8 serial ports).
The c3745 has 2 FastEthernet interfaces on its motherboard (GT96100-FE), 3 subslots for WICs (maximum of 6 serial ports) and 4 Network Module slots (maximum of 32 FastEthernet ports or 16 serial ports).
7200s have a different architecture. Only the 7206 is supported, it has 6 Port Adapters (PA) slots. VXR chassis, NPE-400 and C7200-IO-FE are the default settings in GNS3.
IOS 15 (Mainline)
This router series is still getting new IOS 15.x versions.
The last one at this date is:
File name: c7200-adventerprisek9-mz.152-4.M7.bin
Minimum RAM: 512MB
IOS 12.4.25g (Mainline)
MD5: 3a78cb61831b3ef1530f7402f5986556
File name: c7200-a3jk9s-mz.124-25g.bin
Minimum RAM: 256MB
IOS 12.4.24T5 (Technology train)
Cisco Ios Files For Gns3
This one is not the latest 12.4 version but it is easier to find.
MD5: 3c4148f62acf56602ce3b371ebae60c9
File name: c7200-adventerprisek9-mz.124-24.T5
Minimum RAM: 256MB
Proposed idle-PC value: 0x606df838
Ios Image Download For Gns3
At this moment, it is not possible to emulate Catalyst switches with Dynamip. This is due to the impossibility to emulate ASIC processors used in those type of devices. For switching you can use IOU L2 image or vIOS L2 images with Qemu.
However, if you want to use Dynamips you can use the EtherSwitch module with 2600s, 3600s and 3700s Series. Keep in mind that this module works differently (uses the vlan database etc.) and doesn’t support the following features:
Cisco 3750 Ios Image Download For Gns3 Vmware
Access Switch Device Manager (SDM) Template
ACL – Improved Merging Algorithm
ARP Optimization
BGP Increased Support of Numbered as-path Access Lists to 500
BGP Restart Neighbor Session After max-prefix Limit Reached
BGP Route-Map Continue Support for Outbound Policy
Clear Counters Per Port
DHCP Snooping
DHCP Snooping Counters
Diagnostics Options on bootup
ErrDisable Reactivation Per Port
ErrDisable timeout
EtherChannel – Flexible PAgP
Etherchannel Guard
Fallback Bridging
Flex Link Bi-directional Fast Convergence
Flex Link VLAN Load-Balancing
Flex Links Interface Preemption
GOLD – Generic Online Diagnostics
IEEE 802.1ab, Link Layer Discovery Protocol
IEEE 802.1s – Multiple Spanning Tree (MST) Standard Compliance
IEEE 802.1s VLAN Multiple Spanning Trees
IEEE 802.1t
IEEE 802.1W Spanning Tree Rapid Reconfiguration
IEEE 802.1x – Auth Fail Open
IEEE 802.1x – Auth Fail VLAN
IEEE 802.1x – VLAN Assignment
IEEE 802.1x – Wake on LAN Support
IEEE 802.1X Multi-Domain Authentication
IEEE 802.1x RADIUS Accounting
IEEE 802.1x with Port Security
IEEE 802.3ad Link Aggregation (LACP)
IEEE 802.3af Power over Ethernet
IGMP Fast Leave
IGMP Version 1
IGRP
IP Phone Detection Enhancements
IP Phone Enhancement – PHY Loop Detection
IPSG (IP Source Guard)
Jumbo Frames
L2PT – Layer 2 Protocol Tunneling
MAC Authentication Bypass
MLD Snooping
Multicast Etherchannel Load Balancing
NAC – L2 IEEE 802.1x
NAC – L2 IP
NAC – L2 IP with Auth Fail Open
Packet-Based Storm Control
Per Port Per VLAN Policing
Port Security
Port Security on Private VLAN Ports
Private VLANs
QoS Policy Propagation via Border Gateway Protocol (QPPB)
Rapid-Per-VLAN-Spanning Tree (Rapid-PVST)
Reduced MAC Address Usage
Remote SPAN (RSPAN)
Smart Port
Spanning Tree Protocol (STP) – Loop Guard
Spanning Tree Protocol (STP) – PortFast BPDU Filtering
Spanning Tree Protocol (STP) – Portfast Support for Trunks
Spanning Tree Protocol (STP) – Root Guard
Spanning Tree Protocol (STP) – Uplink Load Balancing
SRR (Shaped Round Robin)
Standby Supervisor Port Usage
STP Syslog Messages
Switching Database Manager (SDM)
Trunk Failover
Trusted boundary (extended trust for CDP devices)
Unicast Mac Filtering
UniDirectional Link Detection (UDLD)
VLAN Access Control List (VACL)
VLAN Aware Port Security
Weighted Tail Drop (WTD)
Routing and Switching Virtual machines from Vendors
To recap: You can import many images using Virtualbox or VMWare. ASIC based models like the Cisco Catalyst switches are impossible to import as a Routing and Switching Image.
If you require more switching features, it is recommended to use larger Virtual Machine Switches and Routers that run inside your choice of Qemu, Virtualbox or VMWare. For advanced switching IOSv and/or IOU is recommended.