loosely routed tunnel

Gleb Smirnoff glebius at cell.sick.ru
Thu Apr 8 06:03:01 PDT 2004

  I need to set up a "loosely routed" tunnel between two boxes, one running
STABLE, and other 5.2.1-RELEASE. Under "loosely routed" I mean that tunnel
route won't be allocated once at tunnel creation, but looked up on every
emitting packet.

  So, I have got a WAN link, and two routers standing on opposite sides of this
link. Both routers are connected to internet. A tunnel is running on IP addresses
provided by upstreams (say x.x.x.x and y.y.y.y). To make tunnel traffic run thru the
WAN link these p2p nets x.x.x.x/30 and y.y.y.y/30 are announced inside using OSPF.
When WAN link breaks tunnel runs thru internet, since OSPF neighbor disappears.

The problem is that when WAN links comes up the tunnel keeps running thru internet.
OSPF routes are successfully received and ping between x.x.x.x and y.y.y.y is
running thru WAN link, but encapsulated packets keep running thru inet.
The desired behavior is to switch back to WAN link, surely.

I have tried gif tunnel, gre tunnel with the above results.

Now I use a UDP tunnel built with ng_iface + ng_ksocket. On 5.2.1-RELEASE the
routing switches back when WAN link is up. On STABLE it does not.
I need to shutdown and restart ng_ksocket manually.

Any ideas any other way I can obtain subj?

Totus tuus, Glebius.

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