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-   -   valid_lft forever preferred_lft forever (https://www.linuxquestions.org/questions/linux-networking-3/valid_lft-forever-preferred_lft-forever-4175444971/)

sulekha 01-10-2013 06:08 AM

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 ???

TB0ne 01-10-2013 09:13 AM

Quote:

Originally Posted by sulekha (Post 4866958)
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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