curious 6.1 GRE behaviour.

David Gilbert dgilbert at dclg.ca
Wed Jun 21 04:08:38 UTC 2006


I was using some GRE tunnels on 6.1-RELEASE recently.  The odd thing
I'm finding is that the initial creation of the tunnel using
cloned_interfaces and ifconfig_gre0="<blah>" results in the gre0
interface being created without the "running" bit set.

tcpdump on the interface or even "ifconfig gre0 up" starts it.

This is also odd because the "UP" flag is set.  Ie:
[1:2:301]root at pbx:~> ifconfig
[...]
gre0: flags=9011<UP,POINTOPOINT,LINK0,MULTICAST> mtu 1476
        tunnel inet x.x.x.x --> y.y.y.y
        inet6 fe80::240:63ff:fee2:eae9%gre0 prefixlen 64 scopeid 0x5 
        inet a.a.a.a --> b.b.b.b netmask 0xfffffffe 
[1:2:302]root at pbx:~> ifconfig gre0 up
[1:3:303]root at pbx:~> ifconfig
[...]
gre0: flags=9051<UP,POINTOPOINT,RUNNING,LINK0,MULTICAST> mtu 1476
        tunnel inet x.x.x.x --> y.y.y.y
        inet6 fe80::240:63ff:fee2:eae9%gre0 prefixlen 64 scopeid 0x5 
        inet a.a.a.a --> b.b.b.b netmask 0xfffffffe 

Dave.


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