RTNETLINK question: no RTM_DELROUTE for IPv4 when link brought down,but for IPv6?

From: Arnd Hannemann
Date: Fri Jun 16 2006 - 11:24:06 EST


Hi,

I'm working on a script which parses "ip monitor route" output to detect changes of the linux kernel routing table.
If an interface is brought down via ifconfig, I expected to see "deleted <route>" messages, but they are missing for IPv4.
Is this the desired behaviour, or a bug(tm)?


IPv6:
goldfinger:~ # uname -a
Linux goldfinger 2.6.15-23-686 #1 SMP PREEMPT Thu May 18 17:31:41 UTC 2006 i686 GNU/Linux

goldfinger:~ # ip -6 monitor route&

goldfinger:~ # ip link set tap1 up
ff00::/8 dev tap1 metric 256 mtu 1500 advmss 1440 hoplimit 4294967295
fe80::/64 dev tap1 metric 256 mtu 1500 advmss 1440 hoplimit 4294967295
local fe80::b889:61ff:fe64:8a92 via :: dev lo proto none metric 0 mtu 16436 advmss 16376 hoplimit 4294967295

goldfinger:~ # ip addr add fccc::1 dev tap1
local fccc::1 via :: dev lo proto none metric 0 mtu 16436 advmss 16376 hoplimit 4294967295

goldfinger:~ # ip route add fccc::2 dev tap1
fccc::2 dev tap1 metric 1024 mtu 1500 advmss 1440 hoplimit 4294967295

goldfinger:~ # ip link set tap1 down
Deleted fccc::2 dev tap1 metric 1024 expires 2133435sec mtu 1500 advmss 1440 hoplimit 4294967295
Deleted fe80::/64 dev tap1 metric 256 expires 2133423sec mtu 1500 advmss 1440 hoplimit 4294967295
Deleted ff00::/8 dev tap1 metric 256 expires 2133423sec mtu 1500 advmss 1440 hoplimit 4294967295
Deleted local fccc::1 via :: dev lo proto none metric 0 mtu 16436 advmss 16376 hoplimit 4294967295
Deleted local fe80::b889:61ff:fe64:8a92 via :: dev lo proto none metric 0 mtu 16436 advmss 16376 hoplimit 4294967295
^^^^^^ for each routing entry a "Deleted <route>" line :-)



IPv4:

root@mrouter4:~ # uname -a
Linux mrouter4 2.6.16-gentoo-r8 #4 PREEMPT Tue Jun 13 00:34:48 CEST 2006 i586 Unknown GNU/Linux
root@mrouter4:~ # ip -4 monitor route&

root@mrouter4:~ # ip link set tap1 up
root@mrouter4:~ # ip addr add 192.168.22.22 dev tap1
root@mrouter4:~ # ip route add 192.168.22.23 dev tap1
root@mrouter4:~ # 192.168.22.23 dev tap1 scope link

root@mrouter4:~ # ip link set tap1 down
root@mrouter4:~ #
^^^^^ no message :-(



Best regards,
Arnd Hannemann
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