The solution to the error “IP overlaps with VlanXXX. VlanXXX: incorrect IP address assignment”

It was necessary to replace the L3 switch of HP with Cisco once and after a similar switch configuration Cisco noticed an error:

172.16.63.0 overlaps with Vlan111
Vlan121: incorrect IP address assignment

As it turned out the network Vlan111 172.16.0.0/18 was ending at 172.16.63.254, it crossed with Vlan121 172.16.63.0/24.

The HP 5800 switch was configured before that and he did not say anything about it, and Cisco refused to accept the command.

Therefore, since IP addresses were used little in the Vlan111 172.16.0.0/18 network, the problem was solved by reducing the mask to 172.16.0.0/19.

After that, the IP address was successfully registered to the Vlan121 interface.

Done.

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