diff --git a/doc/bird.sgml b/doc/bird.sgml
index 8e5641e0..300a71f3 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1329,6 +1329,11 @@ for each neighbor using the following configuration parameters:
circumvent misconfigurations of other routers. Default:
disabled.
+ next hop keep Forward the received Next Hop
+ attribute even in situations where the local address should be
+ used instead, like when the route is sent to an interface with
+ a different subnet. Default: disabled.
+
missing lladdr self|drop|ignoreNext Hop attribute
in BGP-IPv6 sometimes contains just the global IPv6 address,
but sometimes it has to contain both global and link-local
diff --git a/proto/bgp/attrs.c b/proto/bgp/attrs.c
index 98b2f2c2..c27a4988 100644
--- a/proto/bgp/attrs.c
+++ b/proto/bgp/attrs.c
@@ -935,7 +935,8 @@ bgp_create_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *p
rta->dest != RTD_ROUTER ||
ipa_equal(rta->gw, IPA_NONE) ||
ipa_has_link_scope(rta->gw) ||
- (!p->is_internal && (!p->neigh || (rta->iface != p->neigh->iface))))
+ (!p->is_internal && !p->cf->next_hop_keep &&
+ (!p->neigh || (rta->iface != p->neigh->iface))))
set_next_hop(z, p->source_addr);
else
set_next_hop(z, rta->gw);
@@ -1003,10 +1004,13 @@ bgp_update_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *p
/* iBGP -> keep next_hop, eBGP multi-hop -> use source_addr,
* eBGP single-hop -> keep next_hop if on the same iface.
* If the next_hop is zero (i.e. link-local), keep only if on the same iface.
+ *
+ * Note that same-iface-check uses iface from route, which is based on gw.
*/
a = ea_find(e->attrs->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
if (a && !p->cf->next_hop_self &&
- ((p->is_internal && ipa_nonzero(*((ip_addr *) a->u.ptr->data))) ||
+ (p->cf->next_hop_keep ||
+ (p->is_internal && ipa_nonzero(*((ip_addr *) a->u.ptr->data))) ||
(p->neigh && (e->attrs->iface == p->neigh->iface))))
{
/* Leave the original next hop attribute, will check later where does it point */
diff --git a/proto/bgp/bgp.h b/proto/bgp/bgp.h
index c3adf254..13c7fd80 100644
--- a/proto/bgp/bgp.h
+++ b/proto/bgp/bgp.h
@@ -24,6 +24,7 @@ struct bgp_config {
int multihop; /* Number of hops if multihop */
int ttl_security; /* Enable TTL security [RFC5082] */
int next_hop_self; /* Always set next hop to local IP address */
+ int next_hop_keep; /* Do not touch next hop attribute */
int missing_lladdr; /* What we will do when we don' know link-local addr, see MLL_* */
int gw_mode; /* How we compute route gateway from next_hop attr, see GW_* */
int compare_path_lengths; /* Use path lengths when selecting best route */
diff --git a/proto/bgp/config.Y b/proto/bgp/config.Y
index 8b80d7fd..d5e5aaca 100644
--- a/proto/bgp/config.Y
+++ b/proto/bgp/config.Y
@@ -76,7 +76,8 @@ bgp_proto:
| bgp_proto KEEPALIVE TIME expr ';' { BGP_CFG->keepalive_time = $4; }
| bgp_proto MULTIHOP ';' { BGP_CFG->multihop = 64; }
| bgp_proto MULTIHOP expr ';' { BGP_CFG->multihop = $3; if (($3<1) || ($3>255)) cf_error("Multihop must be in range 1-255"); }
- | bgp_proto NEXT HOP SELF ';' { BGP_CFG->next_hop_self = 1; }
+ | bgp_proto NEXT HOP SELF ';' { BGP_CFG->next_hop_self = 1; BGP_CFG->next_hop_keep = 0; }
+ | bgp_proto NEXT HOP KEEP ';' { BGP_CFG->next_hop_keep = 1; BGP_CFG->next_hop_self = 0; }
| bgp_proto MISSING LLADDR SELF ';' { BGP_CFG->missing_lladdr = MLL_SELF; }
| bgp_proto MISSING LLADDR DROP ';' { BGP_CFG->missing_lladdr = MLL_DROP; }
| bgp_proto MISSING LLADDR IGNORE ';' { BGP_CFG->missing_lladdr = MLL_IGNORE; }