bgpd: imported vpn entries get appropriate distance

MPLS VPN networks can either peer with iBGP or eBGP. When
calculating the distance to send to zebra, the imported prefix
is never sent with distance information, even if the vty
command is used under the ipv4 unicast address family:

router bgp 65505 vrf vrf1
 address-family ipv4 unicast
  distance bgp 26 27 28
  [vpn config]

The observation is that the distance sent to zebra for an
imported prefix is still 20:

[..]
VRF vrf1:
B>  192.168.0.0/24 [20/0] via 2.2.2.2 (vrf default) (recursive), label 20, weight 1, 00:00:12
  *                          via 10.125.0.6, ntfp3 (vrf default), label implicit-null/20, weight 1, 00:00:12

The expectation is that the incoming prefix has to follow the
distance that is configured, or the distance derived from the peer
relationship established by the parent prefix.

In the case, an iBGP relationship is done, and no distance
configuration is done, the below show is expected:

   [..]
   VRF vrf1:
   B*>  192.168.0.0/24 [200/0] via 192.168.0.2, r1-gre0 (vrf default), label 20, weight 1, 00:00:12

In the case an iBGP relationship is done, and distance configuration
is performed as below:
   [..]
   distance bgp 21 201 41
   [..]

Then the below show is expected:

   [..]
   VRF vrf1:
   B*>  192.168.0.0/24 [201/0] via 192.168.0.2, r1-gre0 (vrf default), label 20, weight 1, 00:00:12

To get this behaviour, get the peer origin where the prefix is coming
from.

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>

diff --git a/bgpd/bgp_route.c b/bgpd/bgp_route.c
index 87871573f000437d062bb54bc8cff5fcc42907e2..9d776788ee12f0e657287af391417e30d4863db4 100644 (file)
--- a/bgpd/bgp_route.c
+++ b/bgpd/bgp_route.c
@@ -15012,6 +15012,7 @@ uint8_t bgp_distance_apply(const struct prefix *p, struct bgp_path_info *pinfo,
        struct bgp_distance *bdistance;
        struct access_list *alist;
        struct bgp_static *bgp_static;
+       struct bgp_path_info *bpi_ultimate;
 
        if (!bgp)
                return 0;
@@ -15021,6 +15022,12 @@ uint8_t bgp_distance_apply(const struct prefix *p, struct bgp_path_info *pinfo,
        if (pinfo->attr->distance)
                return pinfo->attr->distance;
 
+       /* get peer origin to calculate appropriate distance */
+       if (pinfo->sub_type == BGP_ROUTE_IMPORTED) {
+               bpi_ultimate = bgp_get_imported_bpi_ultimate(pinfo);
+               peer = bpi_ultimate->peer;
+       }
+
        /* Check source address.
         * Note: for aggregate route, peer can have unspec af type.
         */

diff --git a/tests/topotests/bgp_vpnv4_gre/r1/bgpd.conf b/tests/topotests/bgp_vpnv4_gre/r1/bgpd.conf
index 0e2d3a82487bf617dfbeb7bac9997207abf43480..295811bfd02a5e51afd1a0605c81929059ab32a8 100644 (file)
--- a/tests/topotests/bgp_vpnv4_gre/r1/bgpd.conf
+++ b/tests/topotests/bgp_vpnv4_gre/r1/bgpd.conf
@@ -14,6 +14,7 @@ router bgp 65500 vrf vrf1
  bgp router-id 192.0.2.1
  address-family ipv4 unicast
   redistribute connected
+  distance bgp 21 201 41
   label vpn export 101
   rd vpn export 444:1
   rt vpn both 52:100

diff --git a/tests/topotests/bgp_vpnv4_gre/r1/ipv4_routes.json b/tests/topotests/bgp_vpnv4_gre/r1/ipv4_routes.json
index 5f2732aab0b094315ab0ee0917f204e10a96ea07..e57e21bb12be5da760efa9b1df0764d7dc7c6153 100644 (file)
--- a/tests/topotests/bgp_vpnv4_gre/r1/ipv4_routes.json
+++ b/tests/topotests/bgp_vpnv4_gre/r1/ipv4_routes.json
@@ -7,7 +7,7 @@
             "vrfName": "vrf1",
             "selected": true,
             "destSelected": true,
-            "distance": 20,
+            "distance": 201,
             "metric": 0,
             "nexthops": [
                 {