Unable to access switch after made changes in default-gateway.

[cutehameed]

hi all, 

i tried to made some changes with ip dedfault-gateway and due to this i lost my connection. while checking router configuration show run command every thing seems to be ok. please guide how to troubleshoot ip default-gateway? Switch cat 3750, l3.

[Edson A. Hernandez]

1) Verify the configured IP default-gateway is correct:
- Use the "show ip default-gateway" command to verify the current IP default-gateway.
- Verify that the IP address and subnet mask of the default-gateway are correct.
- Make sure that the default-gateway IP address is reachable from the switch by using the "ping" command.

2) Verify the switch management interface configuration:
- Use the "show interface" command to verify the IP address and subnet mask of the management interface.
- Verify that the management interface is in the same subnet as the default-gateway.
- Verify that the management interface is enabled and up/up by checking the interface status.

3) Check the routing table:
- Use the "show ip route" command to verify that the switch has a route to the default-gateway.
- Check if the switch has any other default routes or static routes that may be interfering with the default-gateway.
- Check if there are any routing issues between the switch and the default-gateway.
- Check for duplicate IP addresses:

4) Verify that there are no other devices with the same IP address as the switch management interface or the default-gateway.

**Remember to support with a like to keep the community active***
**Please, if the information was helpful, mark this answer as correct.***

**

[Flavio Miranda]

Hi

 ip default-gateway is only good for accessing the switch from another network.

 You might have a management vlan on the switch.  You need to check on the core what is the IP address of this vlan and the re-ender the command ip default-gateway and this IP.

 Another option is add a static route on the switch

 If you lost access to the switch,  you just need to go to the core or whatever is your layer3 device and access from there.

[Richard Burts]

We have a description of the issue but very little detail to work with. What was changed in the configuration? What was the previous default gateway for the switch? What is the new default gateway for the switch? What vlan has a vlan interface? (is it possible that more than one vlan has a vlan interface?) What is the ip address of the vlan interface? Could you post the output of the command show arp (or show ip arp depending on version of software)? Is the new default gateway address shown in that output?