bird_filters

function update_latency(int link_latency) {
	bgp_community.add((64511, link_latency));
	     if (64511, 9) ~ bgp_community then { bgp_community.delete([(64511, 1..8)]); return 9; }
	else if (64511, 8) ~ bgp_community then { bgp_community.delete([(64511, 1..7)]); return 8; }
	else if (64511, 7) ~ bgp_community then { bgp_community.delete([(64511, 1..6)]); return 7; }
	else if (64511, 6) ~ bgp_community then { bgp_community.delete([(64511, 1..5)]); return 6; }
	else if (64511, 5) ~ bgp_community then { bgp_community.delete([(64511, 1..4)]); return 5; }
	else if (64511, 4) ~ bgp_community then { bgp_community.delete([(64511, 1..3)]); return 4; }
	else if (64511, 3) ~ bgp_community then { bgp_community.delete([(64511, 1..2)]); return 3; }
	else if (64511, 2) ~ bgp_community then { bgp_community.delete([(64511, 1..1)]); return 2; }
        else return 1;
}

function update_bandwidth(int link_bandwidth) {
	bgp_community.add((64511, link_bandwidth));
	     if (64511, 21) ~ bgp_community then { bgp_community.delete([(64511, 22..29)]); return 21; }
	else if (64511, 22) ~ bgp_community then { bgp_community.delete([(64511, 23..29)]); return 22; }
	else if (64511, 23) ~ bgp_community then { bgp_community.delete([(64511, 24..29)]); return 23; }
	else if (64511, 24) ~ bgp_community then { bgp_community.delete([(64511, 25..29)]); return 24; }
	else if (64511, 25) ~ bgp_community then { bgp_community.delete([(64511, 26..29)]); return 25; }
	else if (64511, 26) ~ bgp_community then { bgp_community.delete([(64511, 27..29)]); return 26; }
	else if (64511, 27) ~ bgp_community then { bgp_community.delete([(64511, 28..29)]); return 27; }
	else if (64511, 28) ~ bgp_community then { bgp_community.delete([(64511, 29..29)]); return 28; }
        else return 29;
}

function update_crypto(int link_crypto) {
	bgp_community.add((64511, link_crypto));
	     if (64511, 31) ~ bgp_community then { bgp_community.delete([(64511, 32..34)]); return 31; }
	else if (64511, 32) ~ bgp_community then { bgp_community.delete([(64511, 33..34)]); return 32; }
	else if (64511, 33) ~ bgp_community then { bgp_community.delete([(64511, 34..34)]); return 33; }
        else return 34;
}

	
function update_flags(int link_latency; int link_bandwidth; int link_crypto)
int latency;
int bandwidth;
int crypto;
{
  latency = update_latency(link_latency);
  bandwidth = update_bandwidth(link_bandwidth) - 20;
  crypto = update_crypto(link_crypto) - 30;
  if bandwidth > 4 then bandwidth = 4;
  bgp_local_pref = 1000*bandwidth - 10*latency;
  if crypto < 2 then bgp_local_pref = 0;
     
  return true;
}

gistfile1.txt

(64511, 1) :: latency \in [0, 2.7ms]
(64511, 2) :: latency \in [2.7ms, 7.3ms]
(64511, 3) :: latency \in [7.3ms, 20ms]
(64511, x) :: latency \in [exp(x-1), exp(x)] ms (for x < 10)

(64511, 21) :: bw >= 0.1mbit
(64511, 22) :: bw >= 1mbit
(64511, 23) :: bw >= 10mbit
(64511, 24) :: bw >= 100mbit
(64511, 25) :: bw >= 1000mbit
(64511, 2x) :: bw >= 10^(x-2) mbit
bw = min(up,down) for asymmetric connections

(64511, 31) :: not encrypted
(64511, 32) :: encrypted with unsafe vpn solution
(64511, 33) :: encrypted with safe vpn solution (but no PFS)
(64511, 34) :: encrypted with safe vpn solution with PFS

Propagation:
- for latency pick max(received_route.latency, link_latency)
- for encryption and bw pick min between received BGP community and peer link

improve the print message by printing also the func param (from):

print "nothing matched", link_crypto_class;