Hi What routing protocol do you run ? Would it be possible to just lower the hellos in the used protocoll so it detects a link loss faster ? Regards Matthias On 05/09/13 17:07, thegeezer wrote:
Howdy all, i was wondering if anyone has any idea if there is a means by which i can detect GRE link state ?
what i have is two sites each with two very unstable internet links in order to vpn between them i have ipsec tunnels linking each side twice (four ipsec tunnels in total) i then have 4x GRE tunnels over the top of those in order that i have a secured routable VPN this gives me net.vpn0 net.vpn1 net.vpn2 and net.vpn3 finally i run BIRD over the top which works very well, and synchronises routing tables between the two sites, and allows for me to do such fun as # /etc/init.d/net.vpn0 stop and watch all traffic automagically cut over to another link.
so far so awesome.
however, as i said the internet links are very unstable, and sometimes just blackhole. so what i was hoping to do is just enable keepalives on the gre tunnel. which sadly seems to be cisco only.
can anyone suggest a way of detecting if the GRE is not fully connected ? BIRD only fails over if the net.vpn0 device is down (ifconfig up/down) and for the life of me i cannot find how to detect if a GRE tunnel is 'connected', it seems to just blindly send packets to the remote IP. is my only choice to use L2TP instead ?
thanks in advance for any suggestions; PS if i'm on the wrong list i'd welcome a friendly push to the correct list
-- Matthias Cramer, Erachfeldstrasse 1b, CH-8180 Bülach http://www.freestone.net GnuPG 1024D/2D208250 = DBC6 65B6 7083 1029 781E 3959 B62F DF1C 2D20 8250