[libteam] Add fallback support for single-member-port LAG (#1118)

* [libteam] Add fallback support for single-member-port LAG

* Allow the port to be selected if the LAG is configured
with fallback and port is in defaulted state due to missing
LACP PDUs from remote end
* Only enable port if LAG is admin up and the member port
is link up

* [team] Add lacp fallback config to teamd.j2 template

* [teamd] Resolve config conflict between fallback and minlink

* Remove min_link config if fallback is configured
* Add support for fallback config in minigraph

* [teamd] Only enable fallback if it is single-member-port LAG

Signed-off-by: Haiyang Zheng <haiyang.z@alibaba-inc.com>

* [teamd] Removing the admin status check in lacp_port_link_update

Will submit another pull request to fix this issue.

Signed-off-by: Haiyang Zheng <haiyang.z@alibaba-inc.com>

dockers/docker-teamd/teamd.j2

@@ -4,8 +4,12 @@
     "runner": {
         "name": "lacp",
         "active": true,
+{% if PORTCHANNEL[pc]['fallback'] and ((PORTCHANNEL[pc]['members'] | length) == 1) %}
+        "fallback": {{ PORTCHANNEL[pc]['fallback'] }},
+{% else %}
 {# Use 75% links upperbound as min-links #}
         "min_ports": {{ (PORTCHANNEL[pc]['members'] | length * 0.75) | round(0, 'ceil') | int }},
+{% endif %}
         "tx_hash": ["eth", "ipv4", "ipv6"]
     },
     "link_watch": {

src/libteam/0004-libteam-Add-lacp-fallback-support-for-single-member-.patch

@@ -0,0 +1,104 @@
+From ec966f9a0229bd7226e3abe15b56659b36af9d66 Mon Sep 17 00:00:00 2001
+From: Haiyang Zheng <haiyang.z@alibaba-inc.com>
+Date: Fri, 15 Dec 2017 21:07:53 -0800
+Subject: [patch libteam] [libteam] Add fallback support for single-member-port
+ LAG
+
+Signed-off-by: Haiyang Zheng <haiyang.z@alibaba-inc.com>
+---
+ teamd/teamd_runner_lacp.c | 42 ++++++++++++++++++++++++++++++++++++++++--
+ 1 file changed, 40 insertions(+), 2 deletions(-)
+
+diff --git a/teamd/teamd_runner_lacp.c b/teamd/teamd_runner_lacp.c
+index 9c77fae..a3646a6 100644
+--- a/teamd/teamd_runner_lacp.c
++++ b/teamd/teamd_runner_lacp.c
+@@ -138,6 +138,8 @@ struct lacp {
+ #define		LACP_CFG_DFLT_SYS_PRIO 0xffff
+ 		bool fast_rate;
+ #define		LACP_CFG_DFLT_FAST_RATE false
++		bool fallback;
++#define		LACP_CFG_DFLT_FALLBACK false
+ 		int min_ports;
+ #define		LACP_CFG_DFLT_MIN_PORTS 1
+ 		enum lacp_agg_select_policy agg_select_policy;
+@@ -272,6 +274,11 @@ static int lacp_load_config(struct teamd_context *ctx, struct lacp *lacp)
+ 		lacp->cfg.fast_rate = LACP_CFG_DFLT_FAST_RATE;
+ 	teamd_log_dbg("Using fast_rate \"%d\".", lacp->cfg.fast_rate);
+
++	err = teamd_config_bool_get(ctx, &lacp->cfg.fallback, "$.runner.fallback");
++	if (err)
++		lacp->cfg.fallback = LACP_CFG_DFLT_FALLBACK;
++	teamd_log_dbg("Using fallback \"%d\".", lacp->cfg.fallback);
++
+ 	err = teamd_config_int_get(ctx, &tmp, "$.runner.min_ports");
+ 	if (err) {
+ 		lacp->cfg.min_ports = LACP_CFG_DFLT_MIN_PORTS;
+@@ -308,9 +315,24 @@ static bool lacp_port_loopback_free(struct lacp_port *lacp_port)
+ 	return true;
+ }
+
++/*
++ * is_lacp_fallback_eligible - is lacp_port eligible to go into lacp fallback mode
++ *
++ * Return true if it is, false otherwise
++ */
++static bool is_lacp_fallback_eligible(struct lacp_port *lacp_port)
++{
++	teamd_log_dbg("%s fallback eligible state \"%d \" cfg \"%d\".",
++				lacp_port->tdport->ifname, lacp_port->state,
++				lacp_port->lacp->cfg.fallback);
++	return lacp_port->state == PORT_STATE_DEFAULTED &&
++		lacp_port->lacp->cfg.fallback;
++}
++
+ static bool lacp_port_selectable_state(struct lacp_port *lacp_port)
+ {
+-	if (lacp_port->state == PORT_STATE_CURRENT)
++	if (lacp_port->state == PORT_STATE_CURRENT ||
++	    is_lacp_fallback_eligible(lacp_port))
+ 		return true;
+ 	return false;
+ }
+@@ -318,7 +340,8 @@ static bool lacp_port_selectable_state(struct lacp_port *lacp_port)
+ static bool lacp_port_unselectable_state(struct lacp_port *lacp_port)
+ {
+ 	if (lacp_port->state == PORT_STATE_CURRENT ||
+-	    lacp_port->state == PORT_STATE_EXPIRED)
++	    lacp_port->state == PORT_STATE_EXPIRED ||
++	    is_lacp_fallback_eligible(lacp_port))
+ 		return false;
+ 	return true;
+ }
+@@ -1452,6 +1475,16 @@ static int lacp_state_fast_rate_get(struct teamd_context *ctx,
+ 	return 0;
+ }
+
++static int lacp_state_fallback_get(struct teamd_context *ctx,
++				   struct team_state_gsc *gsc,
++				   void *priv)
++{
++	struct lacp *lacp = priv;
++
++	gsc->data.bool_val = lacp->cfg.fallback;
++	return 0;
++}
++
+ static int lacp_state_select_policy_get(struct teamd_context *ctx,
+ 					struct team_state_gsc *gsc,
+ 					void *priv)
+@@ -1479,6 +1512,11 @@ static const struct teamd_state_val lacp_state_vals[] = {
+ 		.getter = lacp_state_fast_rate_get,
+ 	},
+ 	{
++		.subpath = "fallback",
++		.type = TEAMD_STATE_ITEM_TYPE_BOOL,
++		.getter = lacp_state_fallback_get,
++	},
++	{
+ 		.subpath = "select_policy",
+ 		.type = TEAMD_STATE_ITEM_TYPE_STRING,
+ 		.getter = lacp_state_select_policy_get,
+-- 
+2.7.4
+

src/libteam/Makefile

@@ -18,6 +18,7 @@ $(addprefix $(DEST)/, $(MAIN_TARGET)): $(DEST)/% :
 	git apply ../0001-libteam-Add-team_get_port_enabled-function.patch
 	git apply ../0002-libteam-Temporarily-remove-redundant-debug-mes.patch
 	git apply ../0003-teamd-lacp-runner-will-send-lacp-update-right-after-.patch
+	git apply ../0004-libteam-Add-lacp-fallback-support-for-single-member-.patch
 	popd
 
 	# Obtain debian packaging

src/sonic-config-engine/minigraph.py

@@ -148,7 +148,10 @@ def parse_dpg(dpg, hname):
             pcmbr_list = pcintfmbr.split(';')
             for i, member in enumerate(pcmbr_list):
                 pcmbr_list[i] = port_alias_map.get(member, member)
-            pcs[pcintfname] = {'members': pcmbr_list}
+            if pcintf.find(str(QName(ns, "Fallback"))) != None:
+                pcs[pcintfname] = {'members': pcmbr_list, 'fallback': pcintf.find(str(QName(ns, "Fallback"))).text}
+            else:
+                pcs[pcintfname] = {'members': pcmbr_list}
 
         vlanintfs = child.find(str(QName(ns, "VlanInterfaces")))
         vlan_intfs = []