strange entry in the routing table

Nikos Vassiliadis nvass9573 at gmx.com
Mon Nov 1 16:53:08 UTC 2010


Hi,

While using proxy arp and the same IP address on multiple interfaces,
I noticed a strange entry in the routing table.

192.168.73.60      link#1             UHS         2        0    lo0 =>
192.168.73.60/32   link#3             U           0        0 epair0

The 192.168.73.60/24 address is assigned on an ethernet interface.
Then I assign 192.168.73.60/32 on some epairs with vnets and use
proxyall to proxy arp.

I believe what I am doing is supported(?) and everything seems to work
as expected. Yet this routing table entry is strange.

Thanks for any insights, Nikos

lab# ifconfig
em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=9b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM>
        ether 08:00:27:17:c3:de
        inet 192.168.73.60 netmask 0xffffff00 broadcast 192.168.73.255
        inet6 fe80::a00:27ff:fe17:c3de%em0 prefixlen 64 scopeid 0x1
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384
        options=3<RXCSUM,TXCSUM>
        inet 127.0.0.1 netmask 0xff000000
        inet6 ::1 prefixlen 128
        inet6 fe80::1%lo0 prefixlen 64 scopeid 0x2
        nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL>
lab# netstat -rnfinet
Routing tables

Internet:
Destination        Gateway            Flags    Refs      Use  Netif Expire
default            192.168.73.1       UGS         0       13    em0
127.0.0.1          link#2             UH          0        0    lo0
192.168.73.0/24    link#1             U           1      113    em0
192.168.73.60      link#1             UHS         0        0    lo0
lab# ifconfig epair create
epair0a
lab# ifconfig epair create
epair1a
lab# ifconfig epair0a 192.168.73.60/32
lab# ifconfig epair1a 192.168.73.60/32
lab# arp -an
? (192.168.73.60) at 02:c0:44:00:05:0a on epair1a permanent [ethernet]
? (192.168.73.60) at 02:c0:44:00:03:0a on epair0a permanent [ethernet]
? (192.168.73.1) at 00:13:33:07:90:90 on em0 expires in 970 seconds [ethernet]
? (192.168.73.194) at 70:1a:04:f7:4e:3c on em0 expires in 1194 seconds [ethernet]
? (192.168.73.60) at 08:00:27:17:c3:de on em0 permanent [ethernet]
lab# netstat -rnfinet
Routing tables

Internet:
Destination        Gateway            Flags    Refs      Use  Netif Expire
default            192.168.73.1       UGS         0       13    em0
127.0.0.1          link#2             UH          0        0    lo0
192.168.73.0/24    link#1             U           1      197    em0
192.168.73.60      link#1             UHS         2        0    lo0 =>
192.168.73.60/32   link#3             U           0        0 epair0
lab#


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