add IP mtu support for port and lag (sonic-net#402)

* [mtu] Update the mtu on host interfaces if config DB changes

* [mtu] Get ip mtu val from port while create router interfaces

* Portsorch updates port.m_mtu whenever PORT/LAG mtu changes
* Intfsorch applies port.m_mtu as SAI_ROUTER_INTERFACE_ATTR_MTU
  while creating the router interfaces over the PORT/LAG

Signed-off-by: Haiyang Zheng <[email protected]>

Author: hzheng5

orchagent/intfsorch.cpp

@@ -259,6 +259,10 @@ bool IntfsOrch::addRouterIntfs(Port &port)
     }
     attrs.push_back(attr);
 
+    attr.id = SAI_ROUTER_INTERFACE_ATTR_MTU;
+    attr.value.u32 = port.m_mtu;
+    attrs.push_back(attr);
+
     sai_status_t status = sai_router_intfs_api->create_router_interface(&port.m_rif_id, gSwitchId, (uint32_t)attrs.size(), attrs.data());
     if (status != SAI_STATUS_SUCCESS)
     {
@@ -268,7 +272,7 @@ bool IntfsOrch::addRouterIntfs(Port &port)
 
     gPortsOrch->setPort(port.m_alias, port);
 
-    SWSS_LOG_NOTICE("Create router interface for port %s", port.m_alias.c_str());
+    SWSS_LOG_NOTICE("Create router interface for port %s mtu %u", port.m_alias.c_str(), port.m_mtu);
 
     return true;
 }

orchagent/port.h

@@ -11,6 +11,7 @@ extern "C" {
 #include <map>
 
 #define DEFAULT_PORT_VLAN_ID    1
+#define DEFAULT_MTU        9100
 
 namespace swss {
 
@@ -64,6 +65,7 @@ class Port
     Type                m_type;
     int                 m_index = 0;    // PHY_PORT: index
     int                 m_ifindex = 0;
+    uint32_t            m_mtu = DEFAULT_MTU;
     sai_object_id_t     m_port_id = 0;
     sai_port_fec_mode_t m_fec_mode = SAI_PORT_FEC_MODE_NONE;
     VlanInfo            m_vlan_info;

orchagent/portsorch.cpp

@@ -1127,6 +1127,7 @@ void PortsOrch::doPortTask(Consumer &consumer)
                 {
                     if (setPortMtu(p.m_port_id, mtu))
                     {
+                        p.m_mtu = mtu;
                         SWSS_LOG_NOTICE("Set port %s MTU to %u", alias.c_str(), mtu);
                     }
                     else