GNS3 interface problem

damien2008damien2008 Member Posts: 45 ■□□□□□□□□□

When using GNS3 and VPCS I have 2 PCs connected though a generic Ethernet switch.
VPCS1 can successfully ping VPCS2 – everything OK - see 1st pic

When using a 3700 router issued with the no ip routing command to act as a layer 2 switch I cannot ping between the 2 VPCS PCs

I have put a NM-16ESW slot in R3 – see 2nd pic
The show ip interface brief command from R3 lists f 1/1 and f 1/2 as line status UP but protocol DOWN. – see 3rd pic
This is not expected on a switch interface, I have tried issueing a no shutdown command under the interfaces but still cant get them in an UP and UP status.
Anyone experienced this ?

Just to be clear I am talking about the f 1/1 and f 1/2 R3 interfaces and not the f 0/0 and f 0/1 R3 interfaces which are administratively shut down.


  • OfWolfAndManOfWolfAndMan Member Posts: 923 ■■■■□□□□□□
    Do your show command in VPCS. Do you have the right UDP ports configured on the host?
    :study:Reading: Lab Books, Ansible Documentation, Python Cookbook 2018 Goals: More Ansible/Python work for Automation, IPSpace Automation Course [X], Build Jenkins Framework for Network Automation []
  • damien2008damien2008 Member Posts: 45 ■□□□□□□□□□
    Managed to fix via trial and error
    When connecting hosts to a router or router acting as a switch you have to reload the device for the interfaces to come up, you cannot connect new hosts or devices whilst the device is running
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