From 60f8ce22620d914f6b798ad4fb85d3293ab8b42a Mon Sep 17 00:00:00 2001
From: Maximilian Wilhelm <max@sdn.clinic>
Date: Tue, 3 Jul 2018 16:36:15 +0200
Subject: [PATCH] Use BGP OriginatorID instead of RouterID for tie breaking, if
present.
According to RFC4456 Section 9 the OriginatorID has to be used instead
of the Originator/RouterID when breaking ties, if an OriginatorID set
by a route reflector is present.
In addition a shorter ClusterList (none -> lenght 0) wins the best path
election right after the aforementioned check.
Signed-off-by: Maximilian Wilhelm <max@sdn.clinic>
---
route/bgp_path.go | 29 ++++++++++++++++++++++++++---
1 file changed, 26 insertions(+), 3 deletions(-)
diff --git a/route/bgp_path.go b/route/bgp_path.go
index ee9aca83..4b0b852c 100644
--- a/route/bgp_path.go
+++ b/route/bgp_path.go
@@ -27,6 +27,8 @@ type BGPPath struct {
Communities []uint32
LargeCommunities []types.LargeCommunity
UnknownAttributes []types.UnknownPathAttribute
+ OriginatorID uint32
+ ClusterList []uint32
}
// Length get's the length of serialized path
@@ -110,12 +112,33 @@ func (b *BGPPath) Compare(c *BGPPath) int8 {
// e) TODO: interiour cost (hello IS-IS and OSPF)
- // f)
- if c.BGPIdentifier < b.BGPIdentifier {
+ // f) + RFC4456 9. (Route Reflection)
+ bgpIdentifierC := c.BGPIdentifier
+ bgpIdentifierB := b.BGPIdentifier
+
+ // IF an OriginatorID (set by an RR) is present, use this instead of Originator
+ if c.OriginatorID != 0 {
+ bgpIdentifierC = c.OriginatorID
+ }
+
+ if b.OriginatorID != 0 {
+ bgpIdentifierB = b.OriginatorID
+ }
+
+ if bgpIdentifierC < bgpIdentifierB {
+ return 1
+ }
+
+ if bgpIdentifierC > bgpIdentifierB {
+ return -1
+ }
+
+ // Additionally check for the shorter ClusterList
+ if len(c.ClusterList) < len(b.ClusterList) {
return 1
}
- if c.BGPIdentifier > b.BGPIdentifier {
+ if len(c.ClusterList) > len(b.ClusterList) {
return -1
}
--
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