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bgpd: Configuring default-originate withdraws default route

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Issue:
Configuring default-originate when static default route is previously
advertised results in withdrawal of the route.

Fix :
Delete the adj-out entry for the previously advertised static
default route without sending explicit withdraw message.

Signed-off-by: kssoman <somanks@gmail.com>
This commit is contained in:
Soman K S 2020-04-08 15:04:10 +05:30
parent 63ffd0ea20
commit f55c9a4653
1 changed files with 80 additions and 20 deletions
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100
bgpd/bgp_updgrp_adv.c
View File

@ -533,6 +533,14 @@ void bgp_adj_out_unset_subgroup(struct bgp_node *rn,
if (adj->adv)
bgp_advertise_clean_subgroup(subgrp, adj);
/* If default originate is enabled and the route is default
* route, do not send withdraw. This will prevent deletion of
* the default route at the peer.
*/
if (CHECK_FLAG(subgrp->sflags, SUBGRP_STATUS_DEFAULT_ORIGINATE)
&& is_default_prefix(&rn->p))
return;
if (adj->attr && withdraw) {
/* We need advertisement structure. */
adj->adv = bgp_advertise_new();
@ -636,12 +644,25 @@ void subgroup_announce_table(struct update_subgroup *subgrp,
rn_p, &attr))
bgp_adj_out_set_subgroup(rn, subgrp,
&attr, ri);
else
else {
/* If default originate is enabled for
* the peer, do not send explicit
* withdraw. This will prevent deletion
* of default route advertised through
* default originate
*/
if (CHECK_FLAG(
peer->af_flags[afi][safi],
PEER_FLAG_DEFAULT_ORIGINATE)
&& is_default_prefix(&rn->p))
break;
bgp_adj_out_unset_subgroup(
rn, subgrp, 1,
bgp_addpath_id_for_peer(
peer, afi, safi,
&ri->tx_addpath));
}
}
}
@ -709,7 +730,9 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw)
struct prefix p;
struct peer *from;
struct bgp_node *rn;
struct bgp_path_info *pi;
struct peer *peer;
struct bgp_adj_out *adj;
route_map_result_t ret = RMAP_DENYMATCH;
afi_t afi;
safi_t safi;
@ -732,10 +755,6 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw)
attr.local_pref = bgp->default_local_pref;
memset(&p, 0, sizeof(p));
p.family = afi2family(afi);
p.prefixlen = 0;
if ((afi == AFI_IP6) || peer_cap_enhe(peer, afi, safi)) {
/* IPv6 global nexthop must be included. */
attr.mp_nexthop_len = BGP_ATTR_NHLEN_IPV6_GLOBAL;
@ -778,21 +797,40 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw)
}
}
/* Check if the default route is in local BGP RIB which is
* installed through redistribute or network command
*/
memset(&p, 0, sizeof(p));
p.family = afi2family(afi);
p.prefixlen = 0;
rn = bgp_afi_node_lookup(bgp->rib[afi][safi], afi, safi, &p, NULL);
if (withdraw) {
/* Withdraw the default route advertised using default
* originate
*/
if (CHECK_FLAG(subgrp->sflags, SUBGRP_STATUS_DEFAULT_ORIGINATE))
subgroup_default_withdraw_packet(subgrp);
UNSET_FLAG(subgrp->sflags, SUBGRP_STATUS_DEFAULT_ORIGINATE);
/* If default route is present in the local RIB, advertise the
* route
*/
if (rn != NULL) {
for (pi = bgp_node_get_bgp_path_info(rn); pi;
pi = pi->next) {
if (CHECK_FLAG(pi->flags, BGP_PATH_SELECTED))
if (subgroup_announce_check(
rn, pi, subgrp, &rn->p,
&attr))
bgp_adj_out_set_subgroup(
rn, subgrp, &attr, pi);
}
}
} else {
if (!CHECK_FLAG(subgrp->sflags,
SUBGRP_STATUS_DEFAULT_ORIGINATE)) {
if (CHECK_FLAG(bgp->flags, BGP_FLAG_GRACEFUL_SHUTDOWN))
bgp_attr_add_gshut_community(new_attr);
SET_FLAG(subgrp->sflags,
SUBGRP_STATUS_DEFAULT_ORIGINATE);
subgroup_default_update_packet(subgrp, new_attr, from);
/* The 'neighbor x.x.x.x default-originate' default will
* act as an
* implicit withdraw for any previous UPDATEs sent for
@ -800,15 +838,37 @@ void subgroup_default_originate(struct update_subgroup *subgrp, int withdraw)
* clear adj_out for the 0.0.0.0/0 prefix in the BGP
* table.
*/
memset(&p, 0, sizeof(p));
p.family = afi2family(afi);
p.prefixlen = 0;
if (rn != NULL) {
/* Remove the adjacency for the previously
* advertised default route
*/
adj = adj_lookup(
rn, subgrp,
BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE);
if (adj != NULL) {
/* Clean up previous advertisement. */
if (adj->adv)
bgp_advertise_clean_subgroup(
subgrp, adj);
rn = bgp_afi_node_get(bgp->rib[afi][safi], afi, safi,
&p, NULL);
bgp_adj_out_unset_subgroup(
rn, subgrp, 0,
BGP_ADDPATH_TX_ID_FOR_DEFAULT_ORIGINATE);
/* Remove from adjacency. */
RB_REMOVE(bgp_adj_out_rb, &rn->adj_out,
adj);
/* Free allocated information. */
adj_free(adj);
bgp_unlock_node(rn);
}
}
/* Advertise the default route */
if (CHECK_FLAG(bgp->flags, BGP_FLAG_GRACEFUL_SHUTDOWN))
bgp_attr_add_gshut_community(new_attr);
SET_FLAG(subgrp->sflags,
SUBGRP_STATUS_DEFAULT_ORIGINATE);
subgroup_default_update_packet(subgrp, new_attr, from);
}
}