Question:
Does anybody know why a VLAN would stop passing traffic? Additionally, why would the arp cache entry of a network device (on that same VLAN) that has changed IP addresses still show up in the arp cache two days after it was changed?
Summary:
I have a Cisco 7500 series router with a RSP2 processor running a 12.2(29) IOS image.
On Saturday the Gig card in slot 6/0/0 went bad after a suspect power outage. The switches were moved over to the Gig card in slot6/0/0 started passing traffic. At the same time the management VLAN assigned to the Gig card in slot 5/0/0 stopped passing traffic. However, every user VLAN/subinterface assigned to 5/0/0 is up, but we’ve had sporadic complaints from customers having intermittent printing, IPTV (multicasting), email and connectivity issues. All issues were resolved before we could look at them.
- The “show VLAN” command indicates the router is not receiving traffic on VLAN 600.
- 5/0/0.600 (IP: 132.60.251.1) is up/up and I can ping the subinterface IP address.
- The “show CDP neighbor detail” command shows the Catalyst 4912 directly connected
to interface 5/0/0.
- VTP information is correct and the 4912 is trunking and passing the other 14 user VLANs traversing it.
- The “show arp” command shows every switch IP address but the mac is incomplete.
- Loaded a new IOS image in the router and rebooted.
- Changed the management IP address and VLAN on the 4912 and I could connect to it remotely.
- Reseated the card in slot 5/0/0 and rebooted the switch . . . no change in status. The strange part is that the old IP address of the Catalyst 4912 will not flush out of the arp cache. It’s been over a day since I changed the IP address, upgraded the IOS image and have rebooted the switch.
- The log file shows nothing.
Config:
interface GigabitEthernet5/0/0.600
encapsulation dot1Q 600
ip address 132.60.250.1 255.255.255.0
no ip redirects
no ip unreachables
no ip proxy-arp
ip security extended-ignored
ntp broadcast
Solution:
??? Suspect the router hardware is bad. Especially after the power hit on Saturday night, but can’t prove it as most everything is running behind the router except the management VLAN.
