Merge pull request #18012 from FRRouting/mergify/bp/stable/10.0/pr-17896

bgpd: Send non-transitive extended communities from/to OAD peers (backport #17896)

bgpd/bgp_route.c

@@ -2700,6 +2700,7 @@ bool subgroup_announce_check(struct bgp_dest *dest, struct bgp_path_info *pi,
 	if (nh_reset &&
 	    bgp_path_info_mpath_chkwtd(bgp, pi) &&
 	    (cum_bw = bgp_path_info_mpath_cumbw(pi)) != 0 &&
+<<<<<<< HEAD
 	    !CHECK_FLAG(attr->rmap_change_flags, BATTR_RMAP_LINK_BW_SET))
 		bgp_attr_set_ecommunity(
 			attr,
@@ -2708,6 +2709,94 @@ bool subgroup_announce_check(struct bgp_dest *dest, struct bgp_path_info *pi,
 				CHECK_FLAG(
 					peer->flags,
 					PEER_FLAG_DISABLE_LINK_BW_ENCODING_IEEE)));
+=======
+	    !CHECK_FLAG(attr->rmap_change_flags, BATTR_RMAP_LINK_BW_SET)) {
+		if (CHECK_FLAG(peer->flags, PEER_FLAG_EXTENDED_LINK_BANDWIDTH))
+			bgp_attr_set_ipv6_ecommunity(
+				attr,
+				ecommunity_replace_linkbw(bgp->as,
+							  bgp_attr_get_ipv6_ecommunity(
+								  attr),
+							  cum_bw, false, true));
+		else
+			bgp_attr_set_ecommunity(
+				attr,
+				ecommunity_replace_linkbw(
+					bgp->as, bgp_attr_get_ecommunity(attr),
+					cum_bw,
+					CHECK_FLAG(peer->flags,
+						   PEER_FLAG_DISABLE_LINK_BW_ENCODING_IEEE),
+					false));
+	}
+
+	/*
+	 * Adjust AIGP for propagation when the nexthop is set to ourselves,
+	 * e.g., using "set ip nexthop peer-address" or when advertising to
+	 * EBGP. Note in route reflection the nexthop is usually unmodified
+	 * and the AIGP should not be adjusted in that case.
+	 */
+	if (CHECK_FLAG(attr->flag, ATTR_FLAG_BIT(BGP_ATTR_AIGP)) && AIGP_TRANSMIT_ALLOWED(peer)) {
+		if (nh_reset ||
+		    CHECK_FLAG(attr->rmap_change_flags, BATTR_RMAP_NEXTHOP_PEER_ADDRESS)) {
+			uint64_t aigp = bgp_aigp_metric_total(pi);
+
+			bgp_attr_set_aigp_metric(attr, aigp);
+		}
+	}
+
+	/* Extended communities can be transitive and non-transitive.
+	 * If the extended community is non-transitive, strip it off,
+	 * unless it's a locally originated route (static, aggregate,
+	 * redistributed, etc.).
+	 * draft-uttaro-idr-bgp-oad says:
+	 * Extended communities which are non-transitive across an AS
+	 * boundary MAY be advertised over an EBGP-OAD session if allowed
+	 * by explicit policy configuration. If allowed, all the members
+	 * of the OAD SHOULD be configured to use the same criteria.
+	 * For example, the Origin Validation State Extended Community,
+	 * defined as non-transitive in [RFC8097], can be advertised to
+	 * peers in the same OAD.
+	 */
+	if (from->sort == BGP_PEER_EBGP && from->sub_sort != BGP_PEER_EBGP_OAD &&
+	    peer->sort == BGP_PEER_EBGP && peer->sub_sort != BGP_PEER_EBGP_OAD &&
+	    pi->sub_type == BGP_ROUTE_NORMAL) {
+		struct ecommunity *new_ecomm;
+		struct ecommunity *old_ecomm;
+
+		old_ecomm = bgp_attr_get_ecommunity(attr);
+		if (old_ecomm) {
+			new_ecomm = ecommunity_dup(old_ecomm);
+			if (ecommunity_strip_non_transitive(new_ecomm)) {
+				bgp_attr_set_ecommunity(attr, new_ecomm);
+				if (!old_ecomm->refcnt)
+					ecommunity_free(&old_ecomm);
+				if (bgp_debug_update(NULL, p, subgrp->update_group, 0))
+					zlog_debug("%pBP: %pFX stripped non-transitive extended communities",
+						   peer, p);
+			} else {
+				ecommunity_free(&new_ecomm);
+			}
+		}
+
+		/* Extended link-bandwidth communities are encoded as IPv6
+		 * address-specific extended communities.
+		 */
+		old_ecomm = bgp_attr_get_ipv6_ecommunity(attr);
+		if (old_ecomm) {
+			new_ecomm = ecommunity_dup(old_ecomm);
+			if (ecommunity_strip_non_transitive(new_ecomm)) {
+				bgp_attr_set_ipv6_ecommunity(attr, new_ecomm);
+				if (!old_ecomm->refcnt)
+					ecommunity_free(&old_ecomm);
+				if (bgp_debug_update(NULL, p, subgrp->update_group, 0))
+					zlog_debug("%pBP: %pFX stripped non-transitive ipv6 extended communities",
+						   peer, p);
+			} else {
+				ecommunity_free(&new_ecomm);
+			}
+		}
+	}
+>>>>>>> f2759c46c (bgpd: Send non-transitive extended communities from/to OAD peers)
 
 	return true;
 }

tests/topotests/bgp_oad/r3/frr.conf

@@ -7,12 +7,14 @@ int r3-eth0
 !
 router bgp 65003
  no bgp ebgp-requires-policy
+ no bgp network import-check
  neighbor 192.168.2.2 remote-as external
  neighbor 192.168.2.2 timers 1 3
  neighbor 192.168.2.2 timers connect 1
  neighbor 192.168.2.2 oad
  !
  address-family ipv4 unicast
+  network 10.10.10.20/32 route-map static
   redistribute connected route-map connected
  exit-address-family
 !
@@ -20,3 +22,7 @@ route-map connected permit 10
  set local-preference 123
  set metric 123
 !
+route-map static permit 10
+ set extcommunity bandwidth 100 non-transitive
+exit
+!

tests/topotests/bgp_oad/test_bgp_oad.py

@@ -60,6 +60,7 @@ def test_bgp_dynamic_capability_role():
     r2 = tgen.gears["r2"]
     r3 = tgen.gears["r3"]
     r4 = tgen.gears["r4"]
+    r5 = tgen.gears["r5"]
 
     def _bgp_converge():
         output = json.loads(r1.vtysh_cmd("show bgp ipv4 unicast 10.10.10.10/32 json"))
@@ -125,6 +126,38 @@ def test_bgp_dynamic_capability_role():
     _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
     assert result is None, "10.10.10.1/32 should not be advertised to r4 (not OAD peer)"
 
+    def _bgp_check_non_transitive_extended_community(
+        router, arg={"string": "LB:65003:12500000 (100.000 Mbps)"}
+    ):
+        output = json.loads(
+            router.vtysh_cmd("show bgp ipv4 unicast 10.10.10.20/32 json")
+        )
+        expected = {
+            "paths": [
+                {
+                    "extendedCommunity": arg,
+                }
+            ]
+        }
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(
+        _bgp_check_non_transitive_extended_community,
+        r4,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert (
+        result is None
+    ), "10.10.10.20/32 should be received at r4 with non-transitive extended community"
+
+    test_func = functools.partial(
+        _bgp_check_non_transitive_extended_community, r5, None
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert (
+        result is None
+    ), "10.10.10.20/32 should NOT be received at r5 with non-transitive extended community"
+
 
 if __name__ == "__main__":
     args = ["-s"] + sys.argv[1:]