RE: Arp undo issue in all 2.4 and 2.6 kernel releases

[Tim Wright]

Hi folks,
I have run through what you asked, at what seems to be happening is
that, indeed, a second entry is getting added to the local route table
but with a different "src", that being the "new" address. Is this a
kernel issue or an ifconfig problem?

Thanks,

Tim

[root@nfstest root]# ifconfig eth0:5 10.12.0.22 netmask 255.255.0.0 up
[root@nfstest root]# ip addr
1: lo: <LOOPBACK,UP,10000> mtu 16436 qdisc noqueue
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
5: eth0: <BROADCAST,MULTICAST,UP,10000> mtu 1500 qdisc pfifo_fast qlen
1000
    link/ether 00:80:ad:72:3e:5a brd ff:ff:ff:ff:ff:ff
    inet 10.12.0.20/16 brd 10.12.255.255 scope global eth0
    inet 10.12.0.22/16 brd 10.12.255.255 scope global secondary eth0:5
    inet6 fe80::280:adff:fe72:3e5a/64 scope link
       valid_lft forever preferred_lft forever
6: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
    link/ether 00:80:ad:20:59:8b brd ff:ff:ff:ff:ff:ff
7: eth2: <BROADCAST,MULTICAST> mtu 1500 qdisc noop qlen 1000
    link/ether 00:01:02:c6:fe:c1 brd ff:ff:ff:ff:ff:ff
8: sit0: <NOARP> mtu 1480 qdisc noop
    link/sit 0.0.0.0 brd 0.0.0.0
[root@nfstest root]# ping 10.12.0.22
PING 10.12.0.22 (10.12.0.22) 56(84) bytes of data.
64 bytes from 10.12.0.22: icmp_seq=0 ttl=64 time=0.086 ms
64 bytes from 10.12.0.22: icmp_seq=1 ttl=64 time=0.071 ms

--- 10.12.0.22 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1009ms
rtt min/avg/max/mdev = 0.071/0.078/0.086/0.011 ms, pipe 2
[root@nfstest root]# ip route list table local
broadcast 127.255.255.255 dev lo  proto kernel  scope link  src
127.0.0.1
broadcast 10.12.255.255 dev eth0  proto kernel  scope link  src
10.12.0.20
local 10.12.0.20 dev eth0  proto kernel  scope host  src 10.12.0.20
local 10.12.0.22 dev eth0  proto kernel  scope host  src 10.12.0.20
broadcast 10.12.0.0 dev eth0  proto kernel  scope link  src 10.12.0.20
broadcast 127.0.0.0 dev lo  proto kernel  scope link  src 127.0.0.1
local 127.0.0.1 dev lo  proto kernel  scope host  src 127.0.0.1
local 127.0.0.0/8 dev lo  proto kernel  scope host  src 127.0.0.1
[root@nfstest root]# ifconfig eth0:5 10.12.0.22 netmask 255.255.0.0 down
[root@nfstest root]# ip route list table local
broadcast 127.255.255.255 dev lo  proto kernel  scope link  src
127.0.0.1
broadcast 10.12.255.255 dev eth0  proto kernel  scope link  src
10.12.0.20
local 10.12.0.20 dev eth0  proto kernel  scope host  src 10.12.0.20
broadcast 127.0.0.0 dev lo  proto kernel  scope link  src 127.0.0.1
local 127.0.0.1 dev lo  proto kernel  scope host  src 127.0.0.1
local 127.0.0.0/8 dev lo  proto kernel  scope host  src 127.0.0.1
[root@nfstest root]# ifconfig eth0:5 10.12.0.22 netmask 255.255.0.0 up
[root@nfstest root]# ip route list table local
broadcast 127.255.255.255 dev lo  proto kernel  scope link  src
127.0.0.1
broadcast 10.12.255.255 dev eth0  proto kernel  scope link  src
10.12.0.20
local 10.12.0.20 dev eth0  proto kernel  scope host  src 10.12.0.20
local 10.12.0.22 dev eth0  proto kernel  scope host  src 10.12.0.20
broadcast 127.0.0.0 dev lo  proto kernel  scope link  src 127.0.0.1
local 127.0.0.1 dev lo  proto kernel  scope host  src 127.0.0.1
local 127.0.0.0/8 dev lo  proto kernel  scope host  src 127.0.0.1
[root@nfstest root]# ifconfig eth0:6 10.12.0.22 netmask 255.255.0.0 up
SIOCSIFFLAGS: Cannot assign requested address
[root@nfstest root]# ip route list table local
broadcast 127.255.255.255 dev lo  proto kernel  scope link  src
127.0.0.1
broadcast 10.12.255.255 dev eth0  proto kernel  scope link  src
10.12.0.20
local 10.12.0.20 dev eth0  proto kernel  scope host  src 10.12.0.20
local 10.12.0.22 dev eth0  proto kernel  scope host  src 10.12.0.20
local 10.12.0.22 dev eth0  proto kernel  scope host  src 10.12.0.22
broadcast 127.0.0.0 dev lo  proto kernel  scope link  src 127.0.0.1
local 127.0.0.1 dev lo  proto kernel  scope host  src 127.0.0.1
local 127.0.0.0/8 dev lo  proto kernel  scope host  src 127.0.0.1

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