Re: IPv6, route reflectors and link-local nexthops

11 Oct 2019

      Hi Ondrej,
...
Not really sure how that might happen with direct session. What is your
BIRD version and configs? What routes do you have in routing table?
I'm using a self-compiled bird 2.0.6. RR and R1 have full-views (plus
some internals), so I'm not sure what to answer to "what routes". The
complete configs are a bit complicated (lots of templates and dozens of
other BGP protocols), but the essentials (only the relevant IPv6
protocols and filters) are pretty standard I'd say:

RR's config:

protocol device {
}

protocol bgp R1 {
	local as my_asn;
	neighbor as my_asn;
	direct;
	graceful restart yes;

	rr client;

	ipv6 {
		import keep filtered;
		gateway recursive;
		missing lladdr ignore;

		import none;
		export filter {
			if source != RTS_BGP then reject;
			if net_local() then reject;
			if net_martian() then reject;
			accept;
		};
	};

	neighbor 2001:db8:1::1;
}

protocol bgp R2 {
	local as my_asn;
	graceful restart yes;
	neighbor 2001:db8:2::2 as 4242424242;
	multihop 2;

	ipv6 {
		import keep filtered;
		import filter {
			bgp_community.add((65535, 65281));
			if net ~ [ 2001:db8::/32{64,128} ] then accept;
			reject;
		};
		export filter {
			if net.len == 0 then accept;
			reject;
		};
	};
}

R1's config:

protocol device {
}

protocol bgp RR {
	local as my_asn;
	neighbor as my_asn;
	direct;
	graceful restart yes;

	ipv6 {
		import keep filtered yes;
		next hop self;
		import all;
		export filter {
			if source = RTS_BGP then accept;
			reject;
		};
		gateway recursive;
	};

	neighbor 2001:db8:1::100;
}

If this destillation is missing something, let me know, I can send you
the complete configs privately. But I doubt that there's anything
relevant in there.

Thanks for spending time on this!
Jan-Philipp Litza

-- 
Jan-Philipp Litza
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