dhcpcd repeats interface up and down

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Abstract

Trouble shooting of a problem dhcpcd repeats interface up and down.

Environment

Slackware 14.0

Problem

I configured eth0 to aquire IP address from DHCP in /etc/rc.d/rc.inet1.conf, then

/etc/rc.d/rc.inet1 start

to start network, but eth0 never gets IP address.

/var/log/messages says,

Nov 25 15:28:56 HogeHost dhcpcd[2164]: eth0: eth0: MTU set to 576
Nov 25 15:28:56 HogeHost dhcpcd[1767]: eth0: carrier lost
Nov 25 15:28:56 HogeHost dhcpcd[2173]: eth0: eth0: MTU restored to 1500
Nov 25 15:28:56 HogeHost kernel: [   35.035792] e1000e 0000:00:19.0 eth0: changing MTU from 576 to 1500
Nov 25 15:29:00 HogeHost dhcpcd[1767]: eth0: carrier acquired
Nov 25 15:29:00 HogeHost kernel: [   39.202858] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: None
Nov 25 15:29:00 HogeHost dhcpcd[1767]: eth0: rebinding lease of xxx.xxx.xxx.x
Nov 25 15:29:00 HogeHost dhcpcd[1767]: eth0: acknowledged xxx.xxx.xxx.x from xxx.xxx.xx.xx
Nov 25 15:29:00 HogeHost dhcpcd[1767]: eth0: checking for xxx.xxx.xxx.x
Nov 25 15:29:05 HogeHost dhcpcd[1767]: eth0: leased xxx.xxx.xxx.x for 3582 seconds
Nov 25 15:29:05 HogeHost kernel: [   44.843118] e1000e 0000:00:19.0 eth0: changing MTU from 1500 to 576
Nov 25 15:29:06 HogeHost dhcpcd[2340]: eth0: eth0: MTU set to 576
Nov 25 15:29:06 HogeHost dhcpcd[1767]: eth0: carrier lost
Nov 25 15:29:06 HogeHost dhcpcd[2349]: eth0: eth0: MTU restored to 1500

It is repeating that eth0 carrier acquired and then MTU set to 576 preferred by DHCP server, but setting MTU causes carrier lost.

Solution

Comment out following option in /etc/dhcpcd.conf[1]:

option interface_mtu

This option sets MTU to a value prefered by DHCP server.

References

  1. Gentoo Forums :: View topic - carrier acquired, dhcpcd up, carrier lost - again [SOLVED] http://forums.gentoo.org/viewtopic-t-790041-view-previous.html?sid=a47ae7cfc26f6d7df45471dabe2037c2