Ultimately, GNS3 and Dynamips are good tools for building and troubleshooting router configurations, but switch configuration testing requires actual Cisco switches. For the c3725 image that I used, the spanning tree mode command was not available, so the only spanning tree mode that is available is 802.1d (known in Cisco IOS as Per-VLAN Spanning Tree, PVST+). Spanning Tree Protocol was developed to help prevent layer 2 loops within a network that has redundant links. Trunk Set trunking mode to TRUNK unconditionally Dynamic Trunking Protocol is not supported, so there is no switchport mode dynamic desirable or switchport mode dynamic auto command.Īccess Set trunking mode to ACCESS unconditionally VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2ġ003 tr 101003 1500 1005 0 - srb 1 1002 The show vlan-switch command is used insteadġ default active Fa1/1, Fa1/2, Fa1/3, Fa1/4 Unlike a switch, there is no show vlan command on the router IOS. Configuration on S0, this is the same on S1 and S2 Based on many industry recommendations, I configure the switches to be in VTP transparent mode (effectively disabling VTP on the particular switch, but allowing VTP frames to be forwarded through the switch for switches that support VTP version 2). In this example I configure 2 VLANS named MikesBlog (10) and Internet (20) on all of the routers. The familiar commands from the global configuration mode of the router are available to configure VLANs and VLAN Trunking Protocol (VTP) settings. Multiple VLANs travel across a single link using a trunking protocol such as the industry standard 802.1Q or the Cisco-proprietary Inter-Switch link (ISL).
VLANs allow broadcast domains to be isolated to specific ports across a number of switches in a layer 2 topology. S0(config)#interface range fastethernet 1/0 - 15 Use the switchport command to make the ports switched (rather than routed) ports, Let's get started with the basics of the layer 2 network.Ĭonfiguring the NM-16ESW for Switch-mode Operation In all of the examples, I will be working with the following topology using the Advanced Enterprise Services version of 12.4(15)T7, In this post, I will show how a Cisco c3725 with an NM-16ESW module can be configured to perform specific layer 2 functions such as Spanning Tree Protocol (IEEE, but not Rapid STP or Multipe STP ), VLANs, VLAN Trunking, VLAN Trunk Protocol (VTP). There are ways to perform some of the important features of the layer 2 network that managed switches provide when working with a routed (layer 3) network in GNS3. GNS3 and Dynamips are not good testing and training platforms for the CCNA, CCNP, or CCIE switching topics and not good tools for any IT training courses that need to cover switching related exam objectives.
GNS3 CISCO SWITCH SOFTWARE
Why is this? Cisco has designed a number of application specific integrated circuits (ASICs) that have not been reversed engineered by the Dynamips team or anyone else in the community to create a viable software emulation.
To clarify one thing at the beginning, there is no version of dynamips or GNS3 currently that has the capability of running a Cisco Switch IOS image.
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