When a Babel node restarts, it loses its sequence number, which can cause
its routes to be rejected by peers until the state is cleared out by other
nodes in the network (which can take on the order of minutes).
There are two ways to fix this: Having stable storage to keep the sequence
number across restarts, or picking a different router ID each time.
This implements the latter, by introducing a new option that will cause
BIRD to randomize a high 32 bits of router ID every time it starts up.
This avoids the problem at the cost of not having stable router IDs in
the network.
Thanks to Toke Hoiland-Jorgensen for the patch.
Several changes and bugfixes in Babel, namely:
- Exported route parameters stored directly in route table entry
- Exported non-babel routes no longer stored in per-entry route list
- Route update, selection and retraction simplified and fixed
- Route feasibility is evalualated per update and stored with route
- Unreachable route handling fixed, based on hold interval
- Added 'show babel routes' command
Overall, it fixes some issues with proper propagation of triggered
updates, making Babel convergence after topology change almost
instant.
Also fix several minor bugs and add 'limit' option for k-out-of-j
link sensing strategy. Change default from 8-of-16 to 12-of-16.
Change IHU expiry factor from 1.5 to 3.5 (as in RFC 6126).
This adds support for dual-stack v4/v6 operation to the Babel protocol.
Routing messages will be exchanged over IPv6, but IPv4 routes can be
carried in the messages being exchanged. This matches how the reference
Babel implementation (babeld) works.
The nexthop address for v4 can be configured per interface, and will
default to the first available IPv4 address on the given interface. For
symmetry, a configuration option to configure the IPv6 nexthop address
is also added.
Thanks to Toke Høiland-Jørgensen <toke@toke.dk> for the patch.
Intervals are carried as 16-bit centisecond values, but kept internally
in 16-bit second values, which causes a potential for overflow. This adds
some checks to make sure this does not happen.
Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
This patch implements the IPv6 subset of the Babel routing protocol.
Based on the patch from Toke Hoiland-Jorgensen, with some heavy
modifications and bugfixes.
Thanks to Toke Hoiland-Jorgensen for the original patch.
