1 |
On Thursday 05 Sep 2013 15:49:55 thegeezer wrote: |
2 |
> Howdy all, |
3 |
> i was wondering if anyone has any idea if there is a means by which i |
4 |
> can detect GRE link state ? |
5 |
> |
6 |
> what i have is two sites each with two very unstable internet links |
7 |
> in order to vpn between them i have ipsec tunnels linking each side |
8 |
> twice (four ipsec tunnels in total) |
9 |
|
10 |
I am not sure why you need 4 tunnels, you could just use 1 tunnel as a gateway |
11 |
to gateway setup, but I assume that your particular network topology satisfies |
12 |
your requirements. |
13 |
|
14 |
|
15 |
> i then have 4x GRE tunnels over the top of those in order that i have a |
16 |
> secured routable VPN |
17 |
> this gives me net.vpn0 net.vpn1 net.vpn2 and net.vpn3 |
18 |
> finally i run BIRD over the top which works very well, and synchronises |
19 |
> routing tables between the two sites, and allows for me to do such fun as |
20 |
> # /etc/init.d/net.vpn0 stop |
21 |
> and watch all traffic automagically cut over to another link. |
22 |
> |
23 |
> so far so awesome. |
24 |
> |
25 |
> however, as i said the internet links are very unstable, and sometimes |
26 |
> just blackhole. so what i was hoping to do is just enable keepalives on |
27 |
> the gre tunnel. which sadly seems to be cisco only. |
28 |
|
29 |
I'm no Cisco expert, but I thought that the keepalives are disabled when you |
30 |
use IPSec, because IPSec had Dead Peer Detection for this purpose? |
31 |
|
32 |
|
33 |
> can anyone suggest a way of detecting if the GRE is not fully connected ? |
34 |
> BIRD only fails over if the net.vpn0 device is down (ifconfig up/down) |
35 |
> and for the life of me i cannot find how to detect if a GRE tunnel is |
36 |
> 'connected', it seems to just blindly send packets to the remote IP. |
37 |
> is my only choice to use L2TP instead ? |
38 |
|
39 |
Set your IKE lifetime to something like 86400 sec and your SA lifetime at |
40 |
something like 3600, with dpd enabled and it should (hopefully) work. L2TP is |
41 |
not needed. |
42 |
|
43 |
-- |
44 |
Regards, |
45 |
Mick |