VLAN over loopback interface

[Khoa Nguyen]

Hi,

I notice 2.6.18 and 2.6.24 behave differently when I tried to
configure a vlan interface over loopback (I know, it's silly to create
a vlan over loopback, but our legacy app depends on it). But why under
2.6.24, a vlan over loopback assumes Ethernet encapsulation? And I
can't assign IP address or bring this interface up under 2.6.24. What
should I do to make sure it uses "Local Loopback" encapsulation?

Thanks,
Khoa


2.4.18.1 kernel:
===========
[root@mss2 ~]# vconfig add lo 50
Added VLAN with VID == 50 to IF -:lo:-

[root@mss2 ~]# ifconfig lo.50 192.0.2.2 netmask 255.255.255.255 up
[root@mss2 ~]# ifconfig lo.50
lo.50     Link encap:Local Loopback
          inet addr:192.0.2.2  Mask:255.255.255.255
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)



2.6.24 kernel
=========
vconfig add lo 50
Added VLAN with VID == 50 to IF -:lo:-
[root@mss2 os]# ifconfig lo.50
lo.50     Link encap:Ethernet  HWaddr 00:00:00:00:00:00
          LOOPBACK  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)
[root@mss2 os]# ifconfig lo.50 192.0.2.2 netmask 255.255.255.255 up
SIOCSIFFLAGS: Invalid argument
SIOCSIFFLAGS: Invalid argument
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