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Implements IGP metric comparison for BGP routes.

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This commit is contained in:
Ondrej Zajicek 2010-07-31 01:04:32 +02:00
parent ac3ac49a71
commit d1e146f2f8
7 changed files with 82 additions and 11 deletions
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5
nest/route.h
View file

@ -173,6 +173,7 @@ struct hostentry {
struct iface *iface; /* Chosen outgoing interface */
ip_addr gw; /* Chosen next hop */
byte dest; /* Chosen route destination type (RTD_...) */
u32 igp_metric; /* Chosen route IGP metric */
};
typedef struct rte {
@ -276,6 +277,7 @@ typedef struct rta {
byte flags; /* Route flags (RTF_...), now unused */
byte aflags; /* Attribute cache flags (RTAF_...) */
u16 hash_key; /* Hash over important fields */
u32 igp_metric; /* IGP metric to next hop (for iBGP routes) */
ip_addr gw; /* Next hop */
ip_addr from; /* Advertising router */
struct hostentry *hostentry; /* Hostentry for recursive next-hops */
@ -311,6 +313,9 @@ typedef struct rta {
#define RTAF_CACHED 1 /* This is a cached rta */
#define IGP_METRIC_UNKNOWN 0x80000000 /* Default igp_metric used when no other
protocol-specific metric is availabe */
/*
* Extended Route Attributes
*/

2
nest/rt-attr.c
View file

@ -584,9 +584,11 @@ rta_same(rta *x, rta *y)
x->cast == y->cast &&
x->dest == y->dest &&
x->flags == y->flags &&
x->igp_metric == y->igp_metric &&
ipa_equal(x->gw, y->gw) &&
ipa_equal(x->from, y->from) &&
x->iface == y->iface &&
x->hostentry == y->hostentry &&
ea_same(x->eattrs, y->eattrs));
}

60
nest/rt-table.c
View file

@ -59,6 +59,24 @@ static void rt_prune(rtable *tab);
static inline void rt_schedule_gc(rtable *tab);
/* Like fib_route(), but skips empty net entries */
static net *
net_route(rtable *tab, ip_addr a, int len)
{
ip_addr a0;
net *n;
while (len >= 0)
{
a0 = ipa_and(a, ipa_mkmask(len));
n = fib_find(&tab->fib, &a0, len);
if (n && n->routes)
return n;
len--;
}
return NULL;
}
static void
rte_init(struct fib_node *N)
{
@ -945,16 +963,18 @@ rt_preconfig(struct config *c)
*/
static inline int
hostentry_diff(struct hostentry *he, struct iface *iface, ip_addr gw, byte dest)
hostentry_diff(struct hostentry *he, struct iface *iface, ip_addr gw,
byte dest, u32 igp_metric)
{
return (he->iface != iface) || !ipa_equal(he->gw, gw) || (he->dest != dest);
return (he->iface != iface) || !ipa_equal(he->gw, gw) ||
(he->dest != dest) || (he->igp_metric != igp_metric);
}
static inline int
rta_next_hop_outdated(rta *a)
{
struct hostentry *he = a->hostentry;
return he && hostentry_diff(he, a->iface, a->gw, a->dest);
return he && hostentry_diff(he, a->iface, a->gw, a->dest, a->igp_metric);
}
static inline void
@ -964,6 +984,7 @@ rta_apply_hostentry(rta *a, struct hostentry *he)
a->iface = he->iface;
a->gw = he->gw;
a->dest = he->dest;
a->igp_metric = he->igp_metric;
}
static inline rte *
@ -1449,16 +1470,36 @@ if_local_addr(ip_addr a, struct iface *i)
return 0;
}
static u32
rt_get_igp_metric(rte *rt)
{
rta *a = rt->attrs;
if ((a->source == RTS_OSPF) ||
(a->source == RTS_OSPF_IA) ||
(a->source == RTS_OSPF_EXT1))
return rt->u.ospf.metric1;
if (a->source == RTS_RIP)
return rt->u.rip.metric;
/* Device routes */
if (a->dest != RTD_ROUTER)
return 0;
return IGP_METRIC_UNKNOWN;
}
static int
rt_update_hostentry(rtable *tab, struct hostentry *he)
{
struct iface *old_iface = he->iface;
ip_addr old_gw = he->gw;
byte old_dest = he->dest;
u32 old_metric = he->igp_metric;
int pxlen = 0;
net *n = fib_route(&tab->fib, he->addr, MAX_PREFIX_LENGTH);
if (n && n->routes)
net *n = net_route(tab, he->addr, MAX_PREFIX_LENGTH);
if (n)
{
rta *a = n->routes->attrs;
pxlen = n->n.pxlen;
@ -1489,6 +1530,8 @@ rt_update_hostentry(rtable *tab, struct hostentry *he)
he->gw = a->gw;
he->dest = a->dest;
}
he->igp_metric = he->iface ? rt_get_igp_metric(n->routes) : 0;
}
else
{
@ -1496,12 +1539,13 @@ rt_update_hostentry(rtable *tab, struct hostentry *he)
he->iface = NULL;
he->gw = IPA_NONE;
he->dest = RTD_UNREACHABLE;
he->igp_metric = 0;
}
/* Add a prefix range to the trie */
trie_add_prefix(tab->hostcache->trie, he->addr, MAX_PREFIX_LENGTH, pxlen, MAX_PREFIX_LENGTH);
return hostentry_diff(he, old_iface, old_gw, old_dest);
return hostentry_diff(he, old_iface, old_gw, old_dest, old_metric);
}
static void
@ -1730,9 +1774,9 @@ rt_show(struct rt_show_data *d)
else
{
if (d->show_for)
n = fib_route(&d->table->fib, d->prefix, d->pxlen);
n = net_route(d->table, d->prefix, d->pxlen);
else
n = fib_find(&d->table->fib, &d->prefix, d->pxlen);
n = net_find(d->table, d->prefix, d->pxlen);
if (n)
{
rt_show_net(this_cli, n, d);

22
proto/bgp/attrs.c
View file

@ -1084,8 +1084,13 @@ bgp_rte_better(rte *new, rte *old)
if (new_bgp->is_internal < old_bgp->is_internal)
return 1;
/* Skipping RFC 4271 9.1.2.2. e) */
/* We don't have interior distances */
/* RFC 4271 9.1.2.2. e) Compare IGP metrics */
n = new_bgp->cf->igp_metric ? new->attrs->igp_metric : 0;
o = old_bgp->cf->igp_metric ? old->attrs->igp_metric : 0;
if (n < o)
return 1;
if (n > o)
return 0;
/* RFC 4271 9.1.2.2. f) Compare BGP identifiers */
/* RFC 4456 9. a) Use ORIGINATOR_ID instead of local neighor ID */
@ -1494,7 +1499,18 @@ bgp_get_route_info(rte *e, byte *buf, ea_list *attrs)
eattr *o = ea_find(attrs, EA_CODE(EAP_BGP, BA_ORIGIN));
u32 origas;
buf += bsprintf(buf, " (%d) [", e->pref);
buf += bsprintf(buf, " (%d", e->pref);
if (e->attrs->hostentry)
{
if (!e->attrs->iface)
buf += bsprintf(buf, "/-");
else if (e->attrs->igp_metric >= IGP_METRIC_UNKNOWN)
buf += bsprintf(buf, "/?");
else
buf += bsprintf(buf, "/%d", e->attrs->igp_metric);
}
buf += bsprintf(buf, ") [");
if (p && as_path_get_last(p->u.ptr, &origas))
buf += bsprintf(buf, "AS%u", origas);
if (o)

1
proto/bgp/bgp.h
View file

@ -25,6 +25,7 @@ struct bgp_config {
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 igp_metric; /* Use IGP metrics when selecting best route */
int prefer_older; /* Prefer older routes according to RFC 5004 */
u32 default_local_pref; /* Default value for LOCAL_PREF attribute */
u32 default_med; /* Default value for MULTI_EXIT_DISC attribute */

2
proto/bgp/config.Y
View file

@ -38,6 +38,7 @@ bgp_proto_start: proto_start BGP {
BGP_CFG->connect_retry_time = 120;
BGP_CFG->initial_hold_time = 240;
BGP_CFG->compare_path_lengths = 1;
BGP_CFG->igp_metric = 1;
BGP_CFG->start_delay_time = 5;
BGP_CFG->error_amnesia_time = 300;
BGP_CFG->error_delay_time_min = 60;
@ -78,6 +79,7 @@ bgp_proto:
| 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 IGP METRIC bool ';' { BGP_CFG->igp_metric = $4; }
| bgp_proto PREFER OLDER bool ';' { BGP_CFG->prefer_older = $4; }
| bgp_proto DEFAULT BGP_MED expr ';' { BGP_CFG->default_med = $4; }
| bgp_proto DEFAULT BGP_LOCAL_PREF expr ';' { BGP_CFG->default_local_pref = $4; }

1
proto/bgp/packets.c
View file

@ -823,6 +823,7 @@ bgp_set_next_hop(struct bgp_proto *p, rta *a)
a->gw = ng->addr;
a->iface = ng->iface;
a->hostentry = NULL;
a->igp_metric = 0;
}
else /* GW_RECURSIVE */
rta_set_recursive_next_hop(p->p.table, a, p->igp_table, nexthop, nexthop + second);