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, 10 insertions, 1 deletions

diff --git a/zebra/interface.h b/zebra/interface.h
index 8dcb477f10..cfdaa5d24c 100644
--- a/zebra/interface.h
+++ b/zebra/interface.h
@@ -286,6 +286,9 @@ struct zebra_es_if_info {
 	esi_t esi;
 
 	uint16_t df_pref;
+	uint8_t flags;
+#define ZIF_CFG_ES_FLAG_BYPASS (1 << 0)
+
 	struct zebra_evpn_es *es; /* local ES */
 };
 
@@ -297,7 +300,13 @@ enum zebra_if_flags {
 	ZIF_FLAG_EVPN_MH_UPLINK_OPER_UP = (1 << 1),
 
 	/* Dataplane protodown-on */
-	ZIF_FLAG_PROTODOWN = (1 << 2)
+	ZIF_FLAG_PROTODOWN = (1 << 2),
+
+	/* LACP bypass state is set by the dataplane on a bond member
+	 * and inherited by the bond (if one or more bond members are in
+	 * a bypass state the bond is placed in a bypass state)
+	 */
+	ZIF_FLAG_LACP_BYPASS = (1 << 3)
 };
 
 /* `zebra' daemon local interface structure. */