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bgp: fix case where confederation id same as member-as

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currently the following configuration

dut:

!
interface ntfp2
 ip router isis 1
!
router bgp 200
 no bgp ebgp-requires-policy
 bgp confederation identifier 300
 bgp confederation peers 300
 neighbor 192.168.1.1 remote-as 100
 neighbor 192.168.2.2 remote-as 300
 !
 address-family ipv4 unicast
  neighbor 192.168.2.2 default-originate
 exit-address-family
!
router isis 1
 is-type level-2-only
 net 49.0001.0002.0002.0002.00
 redistribute ipv4 connected level-2
!
end

router:

!
interface ntfp2
 ip router isis 1
 isis circuit-type level-2-only
!
router bgp 300
 no bgp ebgp-requires-policy
 bgp confederation identifier 300
 bgp confederation peers 200
 neighbor 192.168.2.1 remote-as 200
 neighbor 192.168.3.2 remote-as 400
 !
 address-family ipv4 unicast
  network 3.3.3.0/24
 exit-address-family
!
router isis 1
 is-type level-2-only
 net 49.0001.0003.0003.0003.00
 redistribute ipv4 connected level-2
!
end

on dut result of show bgp ipv4 unicast command is:
show bgp ipv4 unicast

  BGP table version is 1, local router ID is 192.168.2.1, vrf id 0
  Default local pref 100, local AS 200
  Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
                 i internal, r RIB-failure, S Stale, R Removed
  Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
  Origin codes:  i - IGP, e - EGP, ? - incomplete
  RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
  *> 1.1.1.0/24       192.168.1.1              0             0 100 i

instead of

sho bgp ipv4 unicast
BGP table version is 3, local router ID is 192.168.2.1, vrf id 0
Default local pref 100, local AS 200
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

   Network          Next Hop            Metric LocPrf Weight Path
*> 1.1.1.0/24       192.168.1.1              0             0 100 i
*> 3.3.3.0/24       192.168.2.2              0    100      0 (300) i
*> 4.4.4.0/24       192.168.3.2              0    100      0 (300) 400 i

Displayed  3 routes and 3 total paths

According to RFC 5065:the usage of one of the member AS number as the
confederation identifier is not forbidden.

fixes are the following

in bgp_route.c:
in bgp_update remove the test for presence of confederation id in
as_path since, this case is allowed;

in bgp_vty.c
bgp_confederation_peers, remove the test on peer as value

in bgpd.c
bgp_confederation_peers_add
remove the test on peer as value
invert the order of setting peer->sort value and peer->local_as,
since peer->sort is depending from current peer->local_as value

bgp_confederation_peers_remove
invert the order of setting peer->sort value and peer->local_as,
since peer->sort is depending from current peer->local_as value

Signed-off-by: Francois Dumontet <francois.dumontet@6wind.com>
This commit is contained in:
Francois Dumontet 2022-11-08 16:25:15 +01:00
parent 53317d66d1
commit b0a8f709a5
5 changed files with 43 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
bgpd/bgp_aspath.c
View File

@ -1187,6 +1187,33 @@ int aspath_loop_check(struct aspath *aspath, as_t asno)
return count;
}
/* AS path loop check. If aspath contains asno
* that is a confed id then return >= 1.
*/
int aspath_loop_check_confed(struct aspath *aspath, as_t asno)
{
struct assegment *seg;
int count = 0;
if (aspath == NULL || aspath->segments == NULL)
return 0;
seg = aspath->segments;
while (seg) {
unsigned int i;
for (i = 0; i < seg->length; i++)
if (seg->type != AS_CONFED_SEQUENCE &&
seg->type != AS_CONFED_SET && seg->as[i] == asno)
count++;
seg = seg->next;
}
return count;
}
/* When all of AS path is private AS return 1. */
bool aspath_private_as_check(struct aspath *aspath)
{

1
bgpd/bgp_aspath.h
View File

@ -111,6 +111,7 @@ extern unsigned int aspath_key_make(const void *p);
extern unsigned int aspath_get_first_as(struct aspath *aspath);
extern unsigned int aspath_get_last_as(struct aspath *aspath);
extern int aspath_loop_check(struct aspath *aspath, as_t asno);
extern int aspath_loop_check_confed(struct aspath *aspath, as_t asno);
extern bool aspath_private_as_check(struct aspath *aspath);
extern struct aspath *aspath_replace_specific_asn(struct aspath *aspath,
as_t target_asn,

17
bgpd/bgp_route.c
View File

@ -2197,7 +2197,7 @@ bool subgroup_announce_check(struct bgp_dest *dest, struct bgp_path_info *pi,
/* If we're a CONFED we need to loop check the CONFED ID too */
if (CHECK_FLAG(bgp->config, BGP_CONFIG_CONFEDERATION)) {
if (aspath_loop_check(piattr->aspath, bgp->confed_id)) {
if (aspath_loop_check_confed(piattr->aspath, bgp->confed_id)) {
if (bgp_debug_update(NULL, p, subgrp->update_group, 0))
zlog_debug(
"%pBP [Update:SEND] suppress announcement to peer AS %u is AS path.",
@ -4113,16 +4113,23 @@ int bgp_update(struct peer *peer, const struct prefix *p, uint32_t addpath_id,
/* AS path loop check. */
if (do_loop_check) {
if (aspath_loop_check(attr->aspath, bgp->as) > allowas_in ||
(CHECK_FLAG(bgp->config, BGP_CONFIG_CONFEDERATION) &&
(aspath_loop_check(attr->aspath, bgp->confed_id) >
allowas_in))) {
if (aspath_loop_check(attr->aspath, bgp->as) >
peer->allowas_in[afi][safi]) {
peer->stat_pfx_aspath_loop++;
reason = "as-path contains our own AS;";
goto filtered;
}
}
/* If we're a CONFED we need to loop check the CONFED ID too */
if (CHECK_FLAG(bgp->config, BGP_CONFIG_CONFEDERATION) && do_loop_check)
if (aspath_loop_check_confed(attr->aspath, bgp->confed_id) >
peer->allowas_in[afi][safi]) {
peer->stat_pfx_aspath_loop++;
reason = "as-path contains our own confed AS;";
goto filtered;
}
/* Route reflector originator ID check. If ACCEPT_OWN mechanism is
* enabled, then take care of that too.
*/

7
bgpd/bgp_vty.c
View File

@ -1917,13 +1917,6 @@ DEFUN (bgp_confederation_peers,
for (i = idx_asn; i < argc; i++) {
as = strtoul(argv[i]->arg, NULL, 10);
if (bgp->as == as) {
vty_out(vty,
"%% Local member-AS not allowed in confed peer list\n");
continue;
}
bgp_confederation_peers_add(bgp, as);
}
return CMD_SUCCESS;

6
bgpd/bgpd.c
View File

@ -671,7 +671,7 @@ void bgp_confederation_peers_add(struct bgp *bgp, as_t as)
struct peer *peer;
struct listnode *node, *nnode;
if (bgp->as == as)
if (!bgp)
return;
if (bgp_confederation_peers_check(bgp, as))
@ -687,8 +687,8 @@ void bgp_confederation_peers_add(struct bgp *bgp, as_t as)
if (bgp_config_check(bgp, BGP_CONFIG_CONFEDERATION)) {
for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer)) {
if (peer->as == as) {
(void)peer_sort(peer);
peer->local_as = bgp->as;
(void)peer_sort(peer);
if (BGP_IS_VALID_STATE_FOR_NOTIF(
peer->status)) {
peer->last_reset =
@ -738,8 +738,8 @@ void bgp_confederation_peers_remove(struct bgp *bgp, as_t as)
if (bgp_config_check(bgp, BGP_CONFIG_CONFEDERATION)) {
for (ALL_LIST_ELEMENTS(bgp->peer, node, nnode, peer)) {
if (peer->as == as) {
(void)peer_sort(peer);
peer->local_as = bgp->confed_id;
(void)peer_sort(peer);
if (BGP_IS_VALID_STATE_FOR_NOTIF(
peer->status)) {
peer->last_reset =