04-21-2026 04:32 AM
Hi, I am trying to set up intervlan routing on a Cisco WS-C3750X but it isn't working correctly. I have attached two laptops to the switch running Ubuntu as I thought that the problem might lie with Windows so I reformatted them. The laptops can ping the default gateway of their respective vlans but not the default gateway of the second vlan or each other. At the moment I am studying a course for the CCNA so I'm not sure if it is something that I am doing wrong or a fault with the switch as my thinking is that there is some issue with routing on the switch. However, I have bought multiple switches from Ebay but have had the same problem, many of the switches I have sent back thinking there was a fault with the switches. I am now beginning to think that it is something I am doing wrong or at least not properly as I have very little knowledge or experience. I've now run out of ideas and I'm at a loss as to how to troubleshoot this problem further and hope that somebody can help me, please
This is how I configured the switch:
en conf t vlan 10 vlan 20 int g2/0/1 switchport access vlan 10 switchport mode access int g2/0/2 switchport access vlan 20 switchport mode access exit int vlan 10 ip add 10.1.10.254 255.255.255.0 no shut int vlan 20 ip add 10.1.20.254 255.255.255.0 no shut exit ip dhcp excluded-address 10.1.10.254 ip dhcp excluded-address 10.1.20.254 ip dhcp pool VLAN10 network 10.1.10.0 255.255.255.0 default-router 10.1.10.254 ip dhcp pool VLAN20 network 10.1.20.0 255.255.255.0 default-router 10.1.20.254 ip routing end
And these are various screenshots from the switch:
Solved! Go to Solution.
04-27-2026 06:19 AM
Thanks
Nick
04-23-2026 12:01 PM
04-23-2026 11:57 AM
Try disabling the Windows local firewall.
04-28-2026 09:29 AM
Hi, having solved my problem with help I just wanted to thank everybody who took the time to reply to me, it was most appreciated. I hope you all see this message as I was so impressed with the response.
Nick
05-12-2026 03:19 AM
Hi, I am not sure if I can still add to this post or if I need to start a new post. I've mostly solved the problems I was having with my little network. However, one problem remains, whilst it all works when I'm using Ubuntu and I had been using Ubuntu. However, it still fails to work correctly when I'm using Windows 10 on the network. I've definitely now narrowed it down to something that Windows 10 is doing and I think it is the firewall (maybe). I connect one laptop running Ubuntu and one laptop running Windows 10 both laptops can ping their default gateways and the gateway of the second vlan. However, whilst the laptop running Windows 10 can ping the laptop running Ubuntu the laptop running Ubuntu can not ping the laptop running Windows 10 unless I disable the Windows Defender firewall. So, whilst I know this isn't to do with Cisco per se. It is a networking problem. So what change would I have to make to the Windows Firewall so that the Ubuntu machine can ping it. I don't really want to have to start making random changes to the Firewall and I certainly don't want to leave it disabled.
Nick
05-12-2026 03:33 AM - edited 05-12-2026 03:33 AM
The problem isn't the network, as you yourself mentioned, it's the Windows firewall. You can simply configure it to accept ICMP. I believe you can easily find how to configure it on Google.
youtube.com/watch?v=O-wti02A1zA&t=66
05-12-2026 04:17 AM
Nice one and thanks, that sorted the problem and I can now ping each machine. Do like this forum, very helpful people on it and it is much appreciated.
Nick
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