Robert,
> Max, > >> [..] >>>> ip addr show [interface] >>>> >>>> and look for the existence of 'LOWER_UP'. E.G. :- >>>> >>>> 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast >>>> qlen 1000 >>>> ... >>> Well, I just looked for 'UP'. Is this wrong? (...will also try to find >>> out myself....) >> One of the main reasons to monitor the interface is as a quick check to see >> if the network is properly connected (rather than doing 'pings' all the >> time) >> ... if you just pull the network plug from your computer you may well find >> that the interface is still 'UP', and it's local IP address may even still >> respond to pings, however you obviously do not have connectivity. The >> 'LOWER_UP' should however have disappeared (you may also see 'NO-CARRIER' >> at this time). So, yes, I would say that just looking for 'UP' is in fact >> wrong. > > Do you have any hint where to look for more information on this? the > ip-utils manpage didn't help. And from looking it's the source code and > the kernel source code as well I can just only guess that it depends on > the driver, whether 'LOWER_UP' is/can be set for an interface. I would > really like to understand the connection between 'UP' and 'LOWER_UP' and > so on, but I'm not a great C coder.... Sorry, I can not tell you anything more - I can only tell you what I have seen on my own Linux systems. There are references on the web such as :- http://www.linuxforums.org/forum/networking/165138-solved-no-carrier-network-interface.html [SOLVED] No-carrier on network interface What does it mean when I have the NO-CARRIER flag on a network interface when using the "ip a" command? EDIT: Nevermind, found out it means the interface is up but the cable is not plugged in. So Lower_up is used to know if the cable is plugged in or not, and No-carrier is used to say that the interface is up and running but the cable is missing. Neat. But this is not anything really definitive if you think some drivers may not pass the information up (or some OSes do not support it). There are probably system that do not display LOWER_UP (e.g. Solaris 2.6), but I have no idea show this translates into other unix/Linux variants. _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
