zebra: support for lacp bypass with EVPN MH

Feature overview:
=================
A 802.3ad bond can be setup to allow lacp-bypass. This is done to enable
servers to pxe boot without a LACP license i.e. allows the bond to go oper
up (with a single link) without LACP converging.

If an ES-bond is oper-up in an "LACP-bypass" state MH treats it as a non-ES
bond. This involves the following special handling -
1. If the bond is in a bypass-state the associated ES is placed in a
bypass state.
2. If an ES is in a bypass state -
a. DF election is disabled (i.e. assumed DF)
b. SPH filter is not installed.
3. MACs learnt via the host bond are advertised with a zero ESI.
When the ES moves out of "bypass" the MACs are moved from a zero-ESI to
the correct non-zero id. This is treated as a local station move.

Implementation:
===============
When (a) an ES is detached from a hostbond or (b) an ES-bond goes into
LACP bypass zebra deletes all the local macs (with that ES as destination)
in the kernel and its local db. BGP re-sends any imported MAC-IP routes
that may exist with this ES destination as remote routes i.e. zebra can
end up programming a MAC that was perviously local as remote pointing
to a VTEP-ECMP group.

When an ES is attached to a hostbond or an ES-bond goes
LACP-up (out of bypss) zebra again deletes all the local macs in the
kernel and its local db. At this point BGP resends any imported MAC-IP
routes that may exist with this ES destination as sync routes i.e.
zebra can end up programming a MAC that was perviously remote
as local pointing to an access port.

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/zebra/zebra_evpn_mh.h b/zebra/zebra_evpn_mh.h
index 94de84ff1..2361a70bf 100644
--- a/zebra/zebra_evpn_mh.h
+++ b/zebra/zebra_evpn_mh.h
@@ -60,6 +60,10 @@ struct zebra_evpn_es {
  * filter, SPH filter and backup NHG for fast-failover
  */
 #define ZEBRA_EVPNES_BR_PORT (1 << 6)
+/* ES is in bypass mode i.e. must not be advertised. ES-bypass is set
+ * when the associated host bond goes into LACP bypass
+ */
+#define ZEBRA_EVPNES_BYPASS (1 << 7)
 
 	/* memory used for adding the es to zmh_info->es_rb_tree */
 	RB_ENTRY(zebra_evpn_es) rb_node;
@@ -376,5 +380,7 @@ extern void zebra_evpn_l2_nh_show(struct vty *vty, bool uj);
 extern void zebra_evpn_acc_bd_svi_set(struct zebra_if *vlan_zif,
 				      struct zebra_if *br_zif, bool is_up);
 extern void zebra_evpn_acc_bd_svi_mac_add(struct interface *vlan_if);
+extern void zebra_evpn_es_bypass_update(struct zebra_evpn_es *es,
+					struct interface *ifp, bool bypass);
 
 #endif /* _ZEBRA_EVPN_MH_H */