This is a nice feature which can be used in cases where you don't run
any dynamic routing protocol over GRE/IPSec tunnel.
If you have OpenBSD as VPN concentrator you can have SNMP traps when
the tunnel is down and take any action etc.

Here is the CISCO implementation:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a008...

Hopefully someone will see this and eventually purpose a alternate
solution or implement keepalives in the distribution.

Rgds, Alex


On 5/17/07, Stuart Henderson <stu@spacehopper.org> wrote:
quoted text
> On 2007/05/17 18:02, Alex Berdan wrote:
> > I was curious about the GRE implementation on OpenBSD as in CISCO
> > there are keepalives
>
> Unfortunately, despite GRE being documented across a number of
> RFCs, there's no mention of this. Looks like it's probably a cisco-
> proprietary extension, I couldn't find any docs on packet formats
> or implementation. Have you come across any?
>
>


-- 

Alex