Commit 087cecd0 authored by Ondřej Zajíček's avatar Ondřej Zajíček

Adds some options and documentation related to recursive next hops.

parent f038f0a6
......@@ -1028,6 +1028,24 @@ for each neighbor using the following configuration parameters:
is configured as a route server (option <cf/rs client/), in
that case default is <cf/drop/, because route servers usually
does not forward packets ifselves.
<tag>gateway direct|recursive</tag>For received routes, their
<cf/gw/ (immediate next hop) attribute is computed from
received <cf/bgp_next_hop/ attribute. This option specifies
how it is computed. Direct mode means that the IP address from
<cf/bgp_next_hop/ is used if it is directly reachable,
otherwise the neighbor IP address is used. Recursive mode
means that the gateway is computed by a IGP routing table
lookup for the IP address from <cf/bgp_next_hop/. Recursive
mode is the behavior specified by the BGP standard. Direct
mode is simpler, does not require any routes in a routing
table, and was used in older versions of BIRD, but does not
handle well nontrivial iBGP setups and multihop. Default:
<cf/direct/ for singlehop eBGP, <cf/recursive/ otherwise.
<tag>igp table <m/name/</tag> Specifies a table that is used
in a recursive gateway mode for computing <cf/gw/ attributes.
Default: the same as the table BGP is connected to.
<tag>password <m/string/</tag> Use this password for MD5 authentication
of BGP sessions. Default: no authentication. Password has to be set by
......
......@@ -951,6 +951,8 @@ bgp_store_error(struct bgp_proto *p, struct bgp_conn *c, u8 class, u32 code)
void
bgp_check(struct bgp_config *c)
{
int internal = (c->local_as == c->remote_as);
if (!c->local_as)
cf_error("Local AS number must be set");
......@@ -960,15 +962,22 @@ bgp_check(struct bgp_config *c)
if (!(c->capabilities && c->enable_as4) && (c->remote_as > 0xFFFF))
cf_error("Neighbor AS number out of range (AS4 not available)");
if ((c->local_as != c->remote_as) && (c->rr_client))
if (!internal && c->rr_client)
cf_error("Only internal neighbor can be RR client");
if ((c->local_as == c->remote_as) && (c->rs_client))
if (internal && c->rs_client)
cf_error("Only external neighbor can be RS client");
if (c->multihop && (c->gw_mode == GW_DIRECT))
cf_error("Multihop BGP cannot use direct gateway mode");
/* Different default based on rs_client */
if (c->missing_lladdr == 0)
if (!c->missing_lladdr)
c->missing_lladdr = c->rs_client ? MLL_DROP : MLL_SELF;
/* Different default for gw_mode */
if (!c->gw_mode)
c->gw_mode = (c->multihop || internal) ? GW_RECURSIVE : GW_DIRECT;
}
static char *bgp_state_names[] = { "Idle", "Connect", "Active", "OpenSent", "OpenConfirm", "Established", "Close" };
......
......@@ -23,6 +23,7 @@ struct bgp_config {
ip_addr source_addr; /* Source address to use */
int next_hop_self; /* Always set next hop to local IP address */
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 */
int prefer_older; /* Prefer older routes according to RFC 5004 */
u32 default_local_pref; /* Default value for LOCAL_PREF attribute */
......@@ -53,6 +54,9 @@ struct bgp_config {
#define MLL_DROP 2
#define MLL_IGNORE 3
#define GW_DIRECT 1
#define GW_RECURSIVE 2
struct bgp_conn {
struct bgp_proto *bgp;
struct birdsock *sk;
......
......@@ -16,15 +16,16 @@ CF_DEFINES
CF_DECLS
CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY, KEEPALIVE,
MULTIHOP, STARTUP, VIA, NEXT, HOP, SELF, DEFAULT, PATH, METRIC,
ERROR, START, DELAY, FORGET, WAIT, ENABLE, DISABLE, AFTER,
BGP_PATH, BGP_LOCAL_PREF, BGP_MED, BGP_ORIGIN, BGP_NEXT_HOP,
BGP_ATOMIC_AGGR, BGP_AGGREGATOR, BGP_COMMUNITY, SOURCE, ADDRESS,
PASSWORD, RR, RS, CLIENT, CLUSTER, ID, AS4, ADVERTISE, IPV4,
CAPABILITIES, LIMIT, PASSIVE, PREFER, OLDER, MISSING, LLADDR,
DROP, IGNORE, ROUTE, REFRESH, INTERPRET, COMMUNITIES,
BGP_ORIGINATOR_ID, BGP_CLUSTER_LIST, IGP, TABLE)
CF_KEYWORDS(BGP, LOCAL, NEIGHBOR, AS, HOLD, TIME, CONNECT, RETRY,
KEEPALIVE, MULTIHOP, STARTUP, VIA, NEXT, HOP, SELF, DEFAULT,
PATH, METRIC, ERROR, START, DELAY, FORGET, WAIT, ENABLE,
DISABLE, AFTER, BGP_PATH, BGP_LOCAL_PREF, BGP_MED, BGP_ORIGIN,
BGP_NEXT_HOP, BGP_ATOMIC_AGGR, BGP_AGGREGATOR, BGP_COMMUNITY,
SOURCE, ADDRESS, PASSWORD, RR, RS, CLIENT, CLUSTER, ID, AS4,
ADVERTISE, IPV4, CAPABILITIES, LIMIT, PASSIVE, PREFER, OLDER,
MISSING, LLADDR, DROP, IGNORE, ROUTE, REFRESH, INTERPRET,
COMMUNITIES, BGP_ORIGINATOR_ID, BGP_CLUSTER_LIST, IGP, TABLE,
GATEWAY, DIRECT, RECURSIVE)
CF_GRAMMAR
......@@ -74,6 +75,8 @@ bgp_proto:
| 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; }
| bgp_proto GATEWAY DIRECT ';' { BGP_CFG->gw_mode = GW_DIRECT; }
| bgp_proto GATEWAY RECURSIVE ';' { BGP_CFG->gw_mode = GW_RECURSIVE; }
| bgp_proto PATH METRIC bool ';' { BGP_CFG->compare_path_lengths = $4; }
| bgp_proto PREFER OLDER bool ';' { BGP_CFG->prefer_older = $4; }
| bgp_proto DEFAULT BGP_MED expr ';' { BGP_CFG->default_med = $4; }
......
......@@ -807,8 +807,7 @@ bgp_set_next_hop(struct bgp_proto *p, rta *a)
struct eattr *nh = ea_find(a->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
ip_addr nexthop = *(ip_addr *) nh->u.ptr->data;
if (!p->is_internal) /* FIXME better option
*/
if (p->cf->gw_mode == GW_DIRECT)
{
neighbor *ng = neigh_find(&p->p, &nexthop, 0) ? : p->neigh;
if (ng->scope == SCOPE_HOST)
......@@ -819,7 +818,7 @@ bgp_set_next_hop(struct bgp_proto *p, rta *a)
a->iface = ng->iface;
a->hostentry = NULL;
}
else
else /* GW_RECURSIVE */
rta_set_recursive_next_hop(p->p.table, a, p->igp_table, &nexthop);
return 1;
......
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