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Old 01-10-2013, 07:08 AM   #1
sulekha
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Registered: Dec 2004
Location: India
Distribution: ubuntu 10.04 , centos 5.5 , Debian lenny, Freenas
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Question valid_lft forever preferred_lft forever


Hi all,

I gave the folowing command

ip addr show eth0

to get the o/p as

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:80:ad:83:e4:75 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.17/24 brd 192.168.0.255 scope global eth0
inet6 fe80::280:adff:fe83:e475/64 scope link
valid_lft forever preferred_lft forever

now my question is what does valid_lft forever preferred_lft forever means ???
 
Old 01-10-2013, 10:13 AM   #2
TB0ne
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Location: Birmingham, Alabama
Distribution: SuSE, RedHat, Slack,CentOS
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Quote:
Originally Posted by sulekha View Post
Hi all,
I gave the folowing command
ip addr show eth0

to get the o/p as

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:80:ad:83:e4:75 brd ff:ff:ff:ff:ff:ff
inet 192.168.0.17/24 brd 192.168.0.255 scope global eth0
inet6 fe80::280:adff:fe83:e475/64 scope link
valid_lft forever preferred_lft forever

now my question is what does valid_lft forever preferred_lft forever means ???
You don't provide all the details (version/distro of Linux? Are you using IPv6? Goals/problems?), but Google turns up lots of answers.

valid_lft = Valid Lifetime
preferred_lft = Preferred Lifetime

Read RFC 3484 "Default Address Selection for Internet Protocol version 6 (IPv6)".

In the case of a tie (ie., source address not decided by destination subnet or other mechanisms), if you have multiple IPv6 addresses on an interface, linux tends to use the last address added.
 
  


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