Removing untagged VLAN from a route-only interface breaks DEFAULT-VLAN

[kpfleming]

I'm running the 09.0.10dT213 router firmware on a stack of three ICX 7150-C12Ps (although this problem was also seen with the 'c' firmware, and I upgraded while troubleshooting).

I had one of the Ethernet interfaces added to a non-default VLAN in untagged mode, and also set to 'route-only' because it was being used as an OSPF transport link. This worked fine.

I have a VE in the default VLAN which handles routing traffic to/from that VLAN and also provides DHCP relay.

When I decommissioned the device which was using that interface, I removed the interface from the non-default VLAN, but did *not* revert to 'no route-only'. No errors were issued at the CLI when I made this change, and the stack continued operating normally. The VE continued working as it had been.

Today I had to power down the stack for a UPS battery installation, and when it came back up VE 1 was gone... it did not appear in 'show running-config' even though it appeared in 'show config'. 'show interface ve 1' showed it as 'down', which isn't something I thought could happen to a VE.

Since the VE was down various parts of my network did not work properly, and I spent quite a long time reviewing the config against my last-known-good backup... multiple reboots, a firmware upgrade, and a complete erase-and-reconfigure did not cure the problem, so I had to conclude it was in the configuration itself.

Finally I noticed the 'route-only' in the interface configuration for that Ethernet interface. Using 'no route-only' at the CLI did not bring the VE back up, but a final reboot *did* bring it back up.

In summary, having an Ethernet interface that is configured in 'route-only' mode also in the default VLAN badly breaks that VLAN; if there's a VE in that VLAN it will not be setup during boot.