Implement BGP Send hold timer according to draft-ietf-idr-bgp-sendholdtimer.
The Send hold timer drops the session if the neighbor is sending keepalives,
but does not receive our messages, causing the TCP connection to stall.
Some BGP capabilities change the BGP behavior in a significant way, so if
the configuration depends on it, it is better to not establish BGP
session when the capability is not available.
Add several BGP option to require individual BGP capabilities during
session negotiation.
The Kernel protocol, even with the option 'learn' enabled, ignores
direct routes created by the OS kernel (on Linux these are routes
with rtm_protocol == RTPROT_KERNEL).
Implement optional behavior where both OS kernel and third-party routes
are learned, it can be enabled by 'learn all' option.
Minor changes by committer.
Methods can now be called as x.m(y), as long as x can have its type
inferred in config time. If used as a command, it modifies the object,
if used as a value, it keeps the original object intact.
Also functions add(x,y), delete(x,y), filter(x,y) and prepend(x,y) now
spit a warning and are considered deprecated.
It's also possible to call a method on a constant, see filter/test.conf
for examples like bgp_path = +empty+.prepend(1).
Inside instruction definitions (filter/f-inst.c), a METHOD_CONSTRUCTOR()
call is added, which registers the instruction as a method for the type
of its first argument. Each type has its own method symbol table and
filter parser switches between them based on the inferred type of the
object calling the method.
Also FI_CLIST_(ADD|DELETE|FILTER) instructions have been split to allow
for this method dispatch. With type inference, it's now possible.
This adds support to the Babel protocol for the RTT extension specified
in draft-ietf-babel-rtt-extension. While this extension is not yet at the
RFC stage, it is one of the more useful extensions to Babel[0], so it
seems worth having in Bird as well.
The extension adds timestamps to Hello and IHU TLVs and uses these to
compute an RTT to each neighbour. An extra per-neighbour cost is then
computed from the RTT based on a minimum and maximum interval and cost
value specified in the configuration. The primary use case for this is
improving routing in a geographically distributed tunnel-based overlay
network.
The implementation follows the babeld implementation when picking
constants and default configuration values. It also uses the same RTT
smoothing algorithm as babeld, and follows it in adding a new 'tunnel'
interface type which enables RTT by default.
[0] https://alioth-lists.debian.net/pipermail/babel-users/2022-April/003932.html
The feature of showing all prefixes inside the given one has been added
in v2.0.9 but not well documented. Fixing it by this update.
Text in doc and commit message added by commiter.
The patch implements an IPv4 via IPv6 extension (RFC 9229) to the Babel
routing protocol (RFC 8966) that allows annoncing routes to an IPv4
prefix with an IPv6 next hop, which makes it possible for IPv4 traffic
to flow through interfaces that have not been assigned an IPv4 address.
The implementation is compatible with the current Babeld version.
Thanks to Toke Høiland-Jørgensen for early review on this work.
Minor changes from committer.
Add static route attribute to set onlink flag for route next hop. Can be
used to build a dynamically routed IP-in-IP overlay network. Usage:
ifname = "tunl0";
onlink = true;
gw = bgp_next_hop;
The import table does not work reliably together with re-evaluation of
routes due to recursive next hops or flowspec validation. We will at
least document that here, as import tables are completely redesigned and
this issue is fixed in BIRD 3.x branch.
The effective keepalive time now scales relative to the negotiated
hold time, to maintain proportion between the keepalive time and the
hold time. This avoids issues when both keepalive and hold times
were configured, the hold time was negotiated to a smaller value,
but the keepalive time stayed the same.
Add new options 'min hold time' and 'min keepalive time', which reject
session attempts with too small hold time.
Improve validation of config options an their documentation.
Thanks to Alexander Zubkov and Sergei Goriunov for suggestions.
BIRD keeps a previous (old) configuration for the purpose of undo. The
existing code frees it after a new configuration is successfully parsed
during reconfiguration. That causes memory usage spikes as there are
temporarily three configurations (old, current, and new). The patch
changes it to free the old one before parsing the new one (as user
already requested a new config). The disadvantage is that undo is
not available after failed reconfiguration.
Add BGP channel option 'next hop prefer global' that modifies BGP
recursive next hop resolution to use global next hop IPv6 address instead
of link-local next hop IPv6 address for immediate next hop of received
routes.
Implement BGP roles as described in RFC 9234. It is a mechanism for
route leak prevention and automatic route filtering based on common BGP
topology relationships. It defines role capability (controlled by 'local
role' option) and OTC route attribute, which is used for automatic route
filtering and leak detection.
Minor changes done by commiter.
For loops allow to iterate over elements in compound data like BGP paths
or community lists. The syntax is:
for [ <type> ] <variable> in <expr> do <command-body>
Allow variable declarations mixed with code, also in nested blocks with
proper scoping, and with variable initializers. E.g:
function fn(int a)
{
int b;
int c = 10;
if a > 20 then
{
b = 30;
int d = c * 2;
print a, b, c, d;
}
string s = "Hello";
}
Use timer (configurable as 'gc period') to schedule routing table
GC/pruning to ensure that prune is done on time but not too often.
Randomize GC timers to avoid concentration of GC events from different
tables in one loop cycle.
Fix a bug that caused minimum inter-GC interval be 5 us instead of 5 s.
Make default 'gc period' adaptive based on number of routing tables,
from 10 s for small setups to 600 s for large ones.
In marge multi-table RS setup, the patch improved time of flushing
a downed peer from 20-30 min to <2 min and removed 40s latencies.
