bgpd: When advertising a multipath route, the attribute set to be
advertised is based on the bestpath attribute set, but the
following attributes are aggregated from the attribute sets
of the multipath constituents:
- AS_PATH
- ORIGIN
- COMMUNITIES
- EXTENDED COMMUNITIES
In addition the route is advertised with the NEXT_HOP set
to the router's interface IP address, instead of the NEXT_HOP
of the best path. This is to ensure that traffic will go to this
router so it can be fanned out via the multipath route.
* bgpd/ecommunity.c
* ecommunity_uniq_sort(): Make this function externally accessible
* bgpd/ecommunity.h
* Add external declaration for ecommunity_uniq_sort()
* bgpd/bgp_mpath.c
* bgp_info_nexthop_cmp(): Replace calls to bgp_attr_extra_get()
to avoid unwanted memory allocation
* bgp_info_mpath_free(): Free aggregate attribute for multipath
* bgp_info_mpath_attr(): Lookup aggregate attribute of a multipath route
* bgp_info_mpath_attr_set(): Set aggregate attribute of a multipath route
* bgp_info_mpath_aggregate_update(): Update the aggregate attribute
of a multipath route
* bgpd/bgp_mpath.h
* bgp_info_mpath: Add pointer to hold aggregate attribute of a multipath
* Add external declarations for new functions
* bgpd/bgp_route.c
* bgp_announce_check(): Use aggregate attribute when announcing multipath
route
* bgp_announce_check_rsclient(): Use aggregate attribute when announcing
multipath route
* bgp_best_selection(): After updating multipath set, update the
multipath aggregate attribute
diff --git a/bgpd/bgp_mpath.c b/bgpd/bgp_mpath.c
index 7944c55..44823c4 100644
--- a/bgpd/bgp_mpath.c
+++ b/bgpd/bgp_mpath.c
@@ -34,6 +34,9 @@
#include "bgpd/bgp_route.h"
#include "bgpd/bgp_attr.h"
#include "bgpd/bgp_debug.h"
+#include "bgpd/bgp_aspath.h"
+#include "bgpd/bgp_community.h"
+#include "bgpd/bgp_ecommunity.h"
#include "bgpd/bgp_mpath.h"
/*
@@ -103,8 +106,8 @@
struct attr_extra *ae1, *ae2;
int compare;
- ae1 = bgp_attr_extra_get (bi1->attr);
- ae2 = bgp_attr_extra_get (bi2->attr);
+ ae1 = bi1->attr->extra;
+ ae2 = bi2->attr->extra;
compare = IPV4_ADDR_CMP (&bi1->attr->nexthop, &bi2->attr->nexthop);
@@ -226,6 +229,8 @@
{
if (mpath && *mpath)
{
+ if ((*mpath)->mp_attr)
+ bgp_attr_unintern ((*mpath)->mp_attr);
XFREE (MTYPE_BGP_MPATH_INFO, *mpath);
*mpath = NULL;
}
@@ -351,6 +356,37 @@
}
/*
+ * bgp_info_mpath_attr
+ *
+ * Given bestpath bgp_info, return aggregated attribute set used
+ * for advertising the multipath route
+ */
+struct attr *
+bgp_info_mpath_attr (struct bgp_info *binfo)
+{
+ if (!binfo->mpath)
+ return NULL;
+ return binfo->mpath->mp_attr;
+}
+
+/*
+ * bgp_info_mpath_attr_set
+ *
+ * Sets the aggregated attribute into bestpath's mpath element
+ */
+static void
+bgp_info_mpath_attr_set (struct bgp_info *binfo, struct attr *attr)
+{
+ struct bgp_info_mpath *mpath;
+ if (!attr && !binfo->mpath)
+ return;
+ mpath = bgp_info_mpath_get (binfo);
+ if (!mpath)
+ return;
+ mpath->mp_attr = attr;
+}
+
+/*
* bgp_info_mpath_update
*
* Compare and sync up the multipath list with the mp_list generated by
@@ -538,3 +574,156 @@
UNSET_FLAG (dmed_best->flags, BGP_INFO_MULTIPATH_CHG);
assert (bgp_info_mpath_first (dmed_best) == 0);
}
+
+/*
+ * bgp_info_mpath_aggregate_update
+ *
+ * Set the multipath aggregate attribute. We need to see if the
+ * aggregate has changed and then set the ATTR_CHANGED flag on the
+ * bestpath info so that a peer update will be generated. The
+ * change is detected by generating the current attribute,
+ * interning it, and then comparing the interned pointer with the
+ * current value. We can skip this generate/compare step if there
+ * is no change in multipath selection and no attribute change in
+ * any multipath.
+ */
+void
+bgp_info_mpath_aggregate_update (struct bgp_info *new_best,
+ struct bgp_info *old_best)
+{
+ struct bgp_info *mpinfo;
+ struct aspath *aspath;
+ struct aspath *asmerge;
+ struct attr *new_attr, *old_attr;
+ u_char origin, attr_chg;
+ struct community *community, *commerge;
+ struct ecommunity *ecomm, *ecommerge;
+ struct attr_extra *ae;
+ struct attr attr = { 0 };
+
+ if (old_best && (old_best != new_best) &&
+ (old_attr = bgp_info_mpath_attr (old_best)))
+ {
+ bgp_attr_unintern (old_attr);
+ bgp_info_mpath_attr_set (old_best, NULL);
+ }
+
+ if (!new_best)
+ return;
+
+ if (!bgp_info_mpath_count (new_best))
+ {
+ if ((new_attr = bgp_info_mpath_attr (new_best)))
+ {
+ bgp_attr_unintern (new_attr);
+ bgp_info_mpath_attr_set (new_best, NULL);
+ SET_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED);
+ }
+ return;
+ }
+
+ /*
+ * Bail out here if the following is true:
+ * - MULTIPATH_CHG bit is not set on new_best, and
+ * - ATTR_CHANGED bit is not set on new_best or any of the multipaths
+ */
+ attr_chg = 0;
+ if (CHECK_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED))
+ attr_chg = 1;
+ else
+ for (mpinfo = bgp_info_mpath_first (new_best); mpinfo;
+ mpinfo = bgp_info_mpath_next (mpinfo))
+ {
+ if (CHECK_FLAG (mpinfo->flags, BGP_INFO_ATTR_CHANGED))
+ {
+ attr_chg = 1;
+ break;
+ }
+ }
+ if (!CHECK_FLAG (new_best->flags, BGP_INFO_MULTIPATH_CHG) && !attr_chg)
+ {
+ assert (bgp_info_mpath_attr (new_best));
+ return;
+ }
+
+ bgp_attr_dup (&attr, new_best->attr);
+
+ /* aggregate attribute from multipath constituents */
+ aspath = aspath_dup (attr.aspath);
+ origin = attr.origin;
+ community = attr.community ? community_dup (attr.community) : NULL;
+ ae = attr.extra;
+ ecomm = (ae && ae->ecommunity) ? ecommunity_dup (ae->ecommunity) : NULL;
+
+ for (mpinfo = bgp_info_mpath_first (new_best); mpinfo;
+ mpinfo = bgp_info_mpath_next (mpinfo))
+ {
+ asmerge = aspath_aggregate (aspath, mpinfo->attr->aspath);
+ aspath_free (aspath);
+ aspath = asmerge;
+
+ if (origin < mpinfo->attr->origin)
+ origin = mpinfo->attr->origin;
+
+ if (mpinfo->attr->community)
+ {
+ if (community)
+ {
+ commerge = community_merge (community, mpinfo->attr->community);
+ community = community_uniq_sort (commerge);
+ community_free (commerge);
+ }
+ else
+ community = community_dup (mpinfo->attr->community);
+ }
+
+ ae = mpinfo->attr->extra;
+ if (ae && ae->ecommunity)
+ {
+ if (ecomm)
+ {
+ ecommerge = ecommunity_merge (ecomm, ae->ecommunity);
+ ecomm = ecommunity_uniq_sort (ecommerge);
+ ecommunity_free (ecommerge);
+ }
+ else
+ ecomm = ecommunity_dup (ae->ecommunity);
+ }
+ }
+
+ attr.aspath = aspath;
+ attr.origin = origin;
+ if (community)
+ {
+ attr.community = community;
+ attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_COMMUNITIES);
+ }
+ if (ecomm)
+ {
+ ae = bgp_attr_extra_get (&attr);
+ ae->ecommunity = ecomm;
+ attr.flag |= ATTR_FLAG_BIT (BGP_ATTR_EXT_COMMUNITIES);
+ }
+
+ /* Zap multipath attr nexthop so we set nexthop to self */
+ attr.nexthop.s_addr = 0;
+#ifdef HAVE_IPV6
+ if (attr.extra)
+ memset (&attr.extra->mp_nexthop_global, 0, sizeof (struct in6_addr));
+#endif /* HAVE_IPV6 */
+
+ /* TODO: should we set ATOMIC_AGGREGATE and AGGREGATOR? */
+
+ new_attr = bgp_attr_intern (&attr);
+ bgp_attr_extra_free (&attr);
+
+ if (new_attr != bgp_info_mpath_attr (new_best))
+ {
+ if ((old_attr = bgp_info_mpath_attr (new_best)))
+ bgp_attr_unintern (old_attr);
+ bgp_info_mpath_attr_set (new_best, new_attr);
+ SET_FLAG (new_best->flags, BGP_INFO_ATTR_CHANGED);
+ }
+ else
+ bgp_attr_unintern (new_attr);
+}