| Summary: | VLAN interface MTU does not change on changing the base interface MTU | ||
|---|---|---|---|
| Product: | Base System | Reporter: | Praveen <praveenchoudary.gokina> |
| Component: | kern | Assignee: | Gleb Smirnoff <glebius> |
| Status: | New --- | ||
| Severity: | Affects Many People | CC: | glebius, john, melifaro |
| Priority: | --- | ||
| Version: | 10.0-RELEASE | ||
| Hardware: | amd64 | ||
| OS: | Any | ||
I don't think that VLAN MTU should change automatically. In the example given it does make sense to either give a warning or prevent the parent interface MTU from being reduced smaller than any of the VLAN MTU (or conversely increasing the VLAN MTU above that of the parent), but I don't think that increasing the MTU on the parent should have any effect on the VLAN interfaces' MTU. I have certainly had cases where I used different MTU settings for different VLANs on the same parent interface (but of course not higher than the parent). In Linux, when we change parent interface mtu, it will automatically update vlan mtu. We can either make it similar to Linux or handle as you said "give a warning or prevent the parent interface MTU from being reduced smaller than any of the VLAN MTU (or conversely increasing the VLAN MTU above that of the parent)". |
Testmachine details: OS: FREEBSD 10.0 We are using Emulex skyhawk adapter. oce0@pci0:4:0:0: class=0x020000 card=0xe80110df chip=0x072010df rev=0x10 hdr=0x00 vendor = 'Emulex Corporation' device = 'OneConnect NIC (Skyhawk)' class = network subclass = ethernet bar [10] = type Prefetchable Memory, range 64, base rxfb340000, size 16384, enabled bar [18] = type Prefetchable Memory, range 64, base rxfb320000, size 131072, enabled bar [20] = type Prefetchable Memory, range 64, base rxfb300000, size 131072, enabled Steps to recreate problem: 1. Create a VLAN on a jumbo MTU enabled interface. ifconfig oce0 mtu 9000 up ifconfig vlan4 create ifconfig vlan4 vlan 4 vlandev oce0 2. Change the MTU of the base interface to 1500 ifconfig oce0 mtu 1500 ACTUAL RESULTS : VLAN interface MTU does not change to 1500, still shows 9000. EXPECTED RESULT: VLAN interface MTU should change to the base interface MTU value.