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(usagi-users 03153) cannot always delete IPv6 route entry in Fedora core 2 and Core 3



Hi there,

I'm a Ph. D student at Carleton University, Canada. I've developing routing protocols
on Linux.


Recently when I move code from redhat 9.0 to Fedora Core 2 and 3, I found out sometimes
the IPv6 route entry added previously cannot be deleted successfully. Finally I traced down to
the system call to the kernel and did the following experiments:


[root@localhost lqin]# route -A inet6
Kernel IPv6 routing table
Destination Next Hop Flags Metric Ref Use Iface
::1/128 * U 0 310 0 lo
fe80::206:25ff:fea9:b1f9/128 * U 0 0 0 lo
fe80::/64 * U 256 0 0 eth1
fec0::/128 fec0:: UC 0 18 0 eth1
fec0::206:25ff:fea9:b1f9/128 * U 0 21 0 lo
fec0::/64 * U 256 0 0 eth1
ff00::/128 ff00:: UC 0 15 0 eth1
ff00::/8 * U 256 0 0 eth1
*/0 * UD 256 0 0 eth1
*/0 * U 1024 0 0 eth1
[root@localhost lqin]# ip -6 route add fec0::206:25ff:fea9:b1fd/128 dev eth1
[root@localhost lqin]# netstat --inet6 -rn
Kernel IPv6 routing table
Destination Next Hop Flags Metric Ref Use Iface
::1/128 :: U 0 343 0 lo
fe80::206:25ff:fea9:b1f9/128 :: U 0 0 0 lo
fe80::/64 :: U 256 0 0 eth1
fec0::206:25ff:fea9:b1f9/128 :: U 0 24 0 lo
fec0::206:25ff:fea9:b1fd/128 :: U 1024 0 0 eth1
fec0::/64 :: U 256 0 0 eth1
ff00::/8 :: U 256 0 0 eth1
fec0::/64 :: U 256 0 0 eth1
ff00::/8 :: U 256 0 0 eth1
::/0 :: UD 256 0 0 eth1
::/0 :: U 1024 0 0 eth1
::/0 :: U 1024 0 0 eth1
[root@localhost lqin]# ip -6 route del fec0::206:25ff:fea9:b1fd/128 dev eth1
[root@localhost lqin]# netstat --inet6 -rn
Kernel IPv6 routing table
Destination Next Hop Flags Metric Ref Use Iface
::1/128 :: U 0 391 0 lo
fe80::206:25ff:fea9:b1f9/128 :: U 0 0 0 lo
fe80::/64 :: U 256 0 0 eth1
fec0::/128 fec0:: UC 0 6 0 eth1
fec0::206:25ff:fea9:b1f9/128 :: U 0 27 0 lo
fec0::206:25ff:fea9:b1fd/128 :: U 1024 0 0 eth1
fec0::/64 :: U 256 0 0 eth1
fec0::/64 :: U 256 0 0 eth1
ff00::/128 ff00:: UC 0 6 0 eth1
ff00::/8 :: U 256 0 0 eth1
::/0 :: UD 256 0 0 eth1
::/0 :: U 1024 0 0 eth1


It will be successfully if I use command twice in very short time (ine 1 or 2 seconds)
ip -6 route del fec0::206:25ff:fea9:b1fd/128 dev eth1


Here eth1 is a wireless interface


I tested on two Dell tops with Fedora core 2 and 3 with the same problem, but on redhat 9.0,
there is no such problem at all (even with the routing protocol which I work on).


BTW, I've sent the same question to netdev@xxxxxxxxxxx but don't receive reply.


Thanks in advance!

Liang Qin