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bgpd: do allocate vrf label only when necessary

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Today, with the following bgp instance configured, the
local VRF label is allocated even if it is not used.

> router bgp 65500 vrf vrf1
>  address-family ipv4 unicast
>   label vpn export allocation-mode per-nexthop
>   label vpn export auto
>   rd vpn export 444:1
>   rt vpn both 52:100
>   export vpn
>   import vpn

The 'show mpls table' indicates that the 16 label value
is allocated, but never used in the exported prefixes.

> r1# show mpls table
>  Inbound Label  Type  Nexthop         Outbound Label
>  -----------------------------------------------------
>  16             BGP   vrf1            -
>  17             BGP   192.168.255.13  -
>  18             BGP   192.0.2.12      -
>  19             BGP   192.0.2.11      -

Fix this by only allocating new label values when really
used. Consequently, only 3 labels will be allocated instead
of previously 4.

> r1# show mpls table
>  Inbound Label  Type  Nexthop         Outbound Label
>  -----------------------------------------------------
>  16             BGP   192.168.255.13  -
>  17             BGP   192.0.2.11      -
>  18             BGP   192.0.2.12      -

Fixes: 577be36a41 ("bgpd: add support for l3vpn per-nexthop label")

Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
This commit is contained in:
Philippe Guibert 2024-04-09 17:09:39 +02:00
parent 8e7fb950c1
commit 8b27521cfa
3 changed files with 18 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
bgpd/bgp_mplsvpn.c
View File

@ -1441,6 +1441,16 @@ _vpn_leak_from_vrf_get_per_nexthop_label(struct bgp_path_info *pi,
return blnc->label;
}
static mpls_label_t bgp_mplsvpn_get_vpn_label(struct vpn_policy *bgp_policy)
{
if (bgp_policy->tovpn_label == MPLS_LABEL_NONE &&
CHECK_FLAG(bgp_policy->flags, BGP_VPN_POLICY_TOVPN_LABEL_AUTO)) {
bgp_lp_get(LP_TYPE_VRF, bgp_policy, vpn_leak_label_callback);
return MPLS_INVALID_LABEL;
}
return bgp_policy->tovpn_label;
}
/* Filter out all the cases where a per nexthop label is not possible:
* - return an invalid label when the nexthop is invalid
* - return the per VRF label when the per nexthop label is not supported
@ -1469,7 +1479,7 @@ vpn_leak_from_vrf_get_per_nexthop_label(afi_t afi, struct bgp_path_info *pi,
* Fallback to the per VRF label.
*/
bgp_mplsvpn_path_nh_label_unlink(pi);
return from_bgp->vpn_policy[afi].tovpn_label;
return bgp_mplsvpn_get_vpn_label(&from_bgp->vpn_policy[afi]);
}
if (is_bgp_static_route == false && afi == AFI_IP &&
@ -1481,7 +1491,7 @@ vpn_leak_from_vrf_get_per_nexthop_label(afi_t afi, struct bgp_path_info *pi,
* Fallback to the per VRF label.
*/
bgp_mplsvpn_path_nh_label_unlink(pi);
return from_bgp->vpn_policy[afi].tovpn_label;
return bgp_mplsvpn_get_vpn_label(&from_bgp->vpn_policy[afi]);
}
if (is_bgp_static_route == false && afi == AFI_IP6 &&
@ -1495,7 +1505,7 @@ vpn_leak_from_vrf_get_per_nexthop_label(afi_t afi, struct bgp_path_info *pi,
* Fallback to the per VRF label.
*/
bgp_mplsvpn_path_nh_label_unlink(pi);
return from_bgp->vpn_policy[afi].tovpn_label;
return bgp_mplsvpn_get_vpn_label(&from_bgp->vpn_policy[afi]);
}
/* Check the next-hop reachability.
@ -1517,7 +1527,7 @@ vpn_leak_from_vrf_get_per_nexthop_label(afi_t afi, struct bgp_path_info *pi,
* table. Fallback to the per-vrf label
*/
bgp_mplsvpn_path_nh_label_unlink(pi);
return from_bgp->vpn_policy[afi].tovpn_label;
return bgp_mplsvpn_get_vpn_label(&from_bgp->vpn_policy[afi]);
}
if (!nh_valid || !pi->nexthop || pi->nexthop->nexthop_num == 0 ||
@ -1540,7 +1550,7 @@ vpn_leak_from_vrf_get_per_nexthop_label(afi_t afi, struct bgp_path_info *pi,
* Fallback to per-vrf label.
*/
bgp_mplsvpn_path_nh_label_unlink(pi);
return from_bgp->vpn_policy[afi].tovpn_label;
return bgp_mplsvpn_get_vpn_label(&from_bgp->vpn_policy[afi]);
}
return _vpn_leak_from_vrf_get_per_nexthop_label(pi, to_bgp, from_bgp,
@ -1755,12 +1765,10 @@ void vpn_leak_from_vrf_update(struct bgp *to_bgp, /* to */
label_val = vpn_leak_from_vrf_get_per_nexthop_label(
afi, path_vrf, from_bgp, to_bgp);
else
/* per VRF label mode */
label_val = from_bgp->vpn_policy[afi].tovpn_label;
label_val =
bgp_mplsvpn_get_vpn_label(&from_bgp->vpn_policy[afi]);
if (label_val == MPLS_INVALID_LABEL &&
CHECK_FLAG(from_bgp->vpn_policy[afi].flags,
BGP_VPN_POLICY_TOVPN_LABEL_PER_NEXTHOP)) {
if (label_val == MPLS_INVALID_LABEL) {
/* no valid label for the moment
* when the 'bgp_mplsvpn_get_label_per_nexthop_cb' callback gets
* a valid label value, it will call the current function again.

10
bgpd/bgp_mplsvpn.h
View File

@ -170,16 +170,6 @@ static inline int vpn_leak_to_vpn_active(struct bgp *bgp_vrf, afi_t afi,
return 0;
}
/* Is there an "auto" export label that isn't allocated yet? */
if (CHECK_FLAG(bgp_vrf->vpn_policy[afi].flags,
BGP_VPN_POLICY_TOVPN_LABEL_AUTO) &&
(bgp_vrf->vpn_policy[afi].tovpn_label == MPLS_LABEL_NONE)) {
if (pmsg)
*pmsg = "auto label not allocated";
return 0;
}
/* Is there a "manual" export label that isn't allocated yet? */
if (!CHECK_FLAG(bgp_vrf->vpn_policy[afi].flags,
BGP_VPN_POLICY_TOVPN_LABEL_AUTO) &&

2
bgpd/bgp_vty.c
View File

@ -9711,8 +9711,6 @@ DEFPY (af_label_vpn_export,
BGP_VPN_POLICY_TOVPN_LABEL_AUTO);
/* fetch a label */
bgp->vpn_policy[afi].tovpn_label = MPLS_LABEL_NONE;
bgp_lp_get(LP_TYPE_VRF, &bgp->vpn_policy[afi],
vpn_leak_label_callback);
} else {
bgp->vpn_policy[afi].tovpn_label = label;
UNSET_FLAG(bgp->vpn_policy[afi].flags,