I encountered a problem configuring a Cisco Catalyst 3560.
I have a trunk interface connected to a Linux server that operates services on different VLANs.
When I try to ping the router on 192.168.1.182 from a machine in VLAN 110, it works, but when I try for VLAN 98 to ping a host, even the Cisco can't ping itself.
When I looked at the network packets, the router sent ARP requests with a wrong tag and the wrong source address:
who has 192.168.3.2? Tell 192.168.1.182
show interfaces showed the VLAN interface connected sometimes (I can't manage to find out how it is decided to be set 98 up or down). In both cases it didn't work.
The only difference between those VLANs is VLAN 110 has others ports in access mode.
interface GigabitEthernet0/3 switchport trunk encapsulation dot1q switchport trunk allowed vlan 98,110 switchport mode trunk shutdown ! [...] interface GigabitEthernet0/11 switchport access vlan 110 switchport mode access [...] interface Vlan1 no ip address ! interface Vlan98 ip address 192.168.3.1 255.255.255.252 ! interface Vlan110 ip address 192.168.2.182 255.255.255.240 ! ip classless ip http server ! ! ip sla enable reaction-alerts ! ! ! line con 0 line vty 0 4 login line vty 5 15 login ! end