Neutron - Automatic network mtu

现在neutron支持创建不同的网络指定不同的mtu，这个应用场景主要是vlan和vxlan混用的情况下。

具体配置

1、neutron.confnetwork_device_mtu=1450  # 生效的设备：neutron 网络节点上的 qdhcp 和 qrouter network namespace的 qr，qg 和 ns 接口以及对应的 veth tap 设备/usr/lib/python2.7/site-packages/neutron/agent/linux/interface.py  if self.conf.network_device_mtu:            ns_dev.link.set_mtu(self.conf.network_device_mtu)            if self.conf.ovs_use_veth:                root_dev.link.set_mtu(self.conf.network_device_mtu)

2、ml2_conf.inipath_mtu = 9000segment_mtu = 1500

flat网络类型如何获取MTU: /usr/lib/python2.7/site-packages/neutron/plugins/ml2/drivers/type_flat.pyclass FlatTypeDriver(helpers.BaseTypeDriver):    # 父类BaseTypeDriver    """Manage state for flat networks with ML2.    The FlatTypeDriver implements the 'flat' network_type. Flat    network segments provide connectivity between VMs and other    devices using any connected IEEE 802.1D conformant    physical_network, without the use of VLAN tags, tunneling, or    other segmentation mechanisms. Therefore at most one flat network    segment can exist on each available physical_network.    """    def __init__(self):        super(FlatTypeDriver, self).__init__()        self._parse_networks(cfg.CONF.ml2_type_flat.flat_networks)        # 如果定义了flat provider的physet_mtus，取physical_network_mtus和segment_mtu的最小值    def get_mtu(self, physical_network):        seg_mtu = super(FlatTypeDriver, self).get_mtu()        mtu = []        if seg_mtu > 0:            mtu.append(seg_mtu)        if physical_network in self.physnet_mtus:            mtu.append(int(self.physnet_mtus[physical_network]))        return min(mtu) if mtu else 0        /usr/lib/python2.7/site-packages/neutron/plugins/ml2/drivers/helpers.pyclass BaseTypeDriver(api.TypeDriver):    """BaseTypeDriver for functions common to Segment and flat."""    def __init__(self):        try:            self.physnet_mtus = utils.parse_mappings(                cfg.CONF.ml2.physical_network_mtus            )        except Exception:            self.physnet_mtus = []    def get_mtu(self, physical_network=None):        return cfg.CONF.ml2.segment_mtu

vlan网络类型如何获取MTU: class VlanTypeDriver(helpers.SegmentTypeDriver):   # 父类SegmentTypeDriver    """Manage state for VLAN networks with ML2.    The VlanTypeDriver implements the 'vlan' network_type. VLAN    network segments provide connectivity between VMs and other    devices using any connected IEEE 802.1Q conformant    physical_network segmented into virtual networks via IEEE 802.1Q    headers. Up to 4094 VLAN network segments can exist on each    available physical_network.    """    def __init__(self):        super(VlanTypeDriver, self).__init__(VlanAllocation)        self._parse_network_vlan_ranges()        # vlan的获取mtu方式和flat一样    def get_mtu(self, physical_network):        seg_mtu = super(VlanTypeDriver, self).get_mtu()        mtu = []        if seg_mtu > 0:            mtu.append(seg_mtu)        if physical_network in self.physnet_mtus:            mtu.append(int(self.physnet_mtus[physical_network]))        return min(mtu) if mtu else 0        /usr/lib/python2.7/site-packages/neutron/plugins/ml2/drivers/helpers.pyclass BaseTypeDriver(api.TypeDriver):    """BaseTypeDriver for functions common to Segment and flat."""    def __init__(self):        try:            self.physnet_mtus = utils.parse_mappings(                cfg.CONF.ml2.physical_network_mtus            )        except Exception:            self.physnet_mtus = []    def get_mtu(self, physical_network=None):        return cfg.CONF.ml2.segment_mtu        class SegmentTypeDriver(BaseTypeDriver):    """SegmentTypeDriver for segment allocation.    Provide methods helping to perform segment allocation fully or partially    specified.    """    def __init__(self, model):        super(SegmentTypeDriver, self).__init__()        self.model = model        self.primary_keys = set(dict(model.__table__.columns))        self.primary_keys.remove("allocated")

vxlan网络类型如何获取MTU:class VxlanTypeDriver(type_tunnel.EndpointTunnelTypeDriver):   # 父类EndpointTunnelTypeDriver    def __init__(self):        super(VxlanTypeDriver, self).__init__(            VxlanAllocation, VxlanEndpoints)    def get_type(self):        return p_const.TYPE_VXLAN    def initialize(self):        try:            self._initialize(cfg.CONF.ml2_type_vxlan.vni_ranges)        except n_exc.NetworkTunnelRangeError:            LOG.exception(_LE("Failed to parse vni_ranges. "                              "Service terminated!"))            raise SystemExit()                def get_endpoints(self):        """Get every vxlan endpoints from database."""        vxlan_endpoints = self._get_endpoints()        return [{'ip_address': vxlan_endpoint.ip_address,                 'udp_port': vxlan_endpoint.udp_port,                 'host': vxlan_endpoint.host}                for vxlan_endpoint in vxlan_endpoints]    def add_endpoint(self, ip, host, udp_port=p_const.VXLAN_UDP_PORT):        return self._add_endpoint(ip, host, udp_port=udp_port)    def get_mtu(self, physical_network=None):        mtu = super(VxlanTypeDriver, self).get_mtu()        return mtu - p_const.VXLAN_ENCAP_OVERHEAD if mtu else 0  # mtu - vxlan开销，自动减去vxlan overhead        from neutron.plugins.common import constants as p_const/usr/lib/python2.7/site-packages/neutron/plugins/common/constants.py# Network Type MTU overheadGENEVE_ENCAP_MIN_OVERHEAD = 50GRE_ENCAP_OVERHEAD = 42VXLAN_ENCAP_OVERHEAD = 50  # vxlan开销class EndpointTunnelTypeDriver(TunnelTypeDriver):class TunnelTypeDriver(helpers.SegmentTypeDriver):    """Define stable abstract interface for ML2 type drivers.    tunnel type networks rely on tunnel endpoints. This class defines abstract    methods to manage these endpoints.    """    def get_mtu(self, physical_network=None):        seg_mtu = super(TunnelTypeDriver, self).get_mtu()        mtu = []        if seg_mtu > 0:            mtu.append(seg_mtu)        if cfg.CONF.ml2.path_mtu > 0:            mtu.append(cfg.CONF.ml2.path_mtu)        return min(mtu) if mtu else 0

gre网络类型如何获取MTU:class GreTypeDriver(type_tunnel.EndpointTunnelTypeDriver):    # 父类也是EndpointTunnelTypeDriver    def __init__(self):        super(GreTypeDriver, self).__init__(            GreAllocation, GreEndpoints)    def get_type(self):        return p_const.TYPE_GRE    def initialize(self):        try:            self._initialize(cfg.CONF.ml2_type_gre.tunnel_id_ranges)        except n_exc.NetworkTunnelRangeError:            LOG.exception(_LE("Failed to parse tunnel_id_ranges. "                              "Service terminated!"))            raise SystemExit()    def get_endpoints(self):        """Get every gre endpoints from database."""        gre_endpoints = self._get_endpoints()        return [{'ip_address': gre_endpoint.ip_address,                 'host': gre_endpoint.host}                for gre_endpoint in gre_endpoints]    def add_endpoint(self, ip, host):        return self._add_endpoint(ip, host)    def get_mtu(self, physical_network=None):        mtu = super(GreTypeDriver, self).get_mtu(physical_network)        return mtu - p_const.GRE_ENCAP_OVERHEAD if mtu else 0     # mtu - gre开销,自动减去gre overhead        from neutron.plugins.common import constants as p_const/usr/lib/python2.7/site-packages/neutron/plugins/common/constants.py# Network Type MTU overheadGENEVE_ENCAP_MIN_OVERHEAD = 50GRE_ENCAP_OVERHEAD = 42    # gre开销，为什么是42，还不清楚VXLAN_ENCAP_OVERHEAD = 50  # vxlan开销L版发现neutron多了种网络类型geneve，Geneve简介，暂时还不知道怎么玩的http://blog.csdn.net/yeasy/article/details/39928153

3、neutron.confadvertise_mtu = true以前的做法：[root@controller2 ~(keystone_admin)]# cat /etc/neutron/dnsmasq-neutron.conf  # 对所有network都生效dhcp-option-force=26,1450    # 现在可以把这个去掉log-facility=/var/log/neutron/neutron-dnsmasq.log/usr/lib/python2.7/site-packages/neutron/agent/linux/dhcp.pyclass Dnsmasq(DhcpLocalProcess):    # The ports that need to be opened when security policies are active    # on the Neutron port used for DHCP.  These are provided as a convenience    # for users of this class.        if cfg.CONF.advertise_mtu:            mtu = self.network.mtu            # Do not advertise unknown mtu            if mtu > 0:                cmd.append('--dhcp-option-force=option:mtu,%d' % mtu)   # 看这里        # Cap the limit because creating lots of subnets can inflate        # this possible lease cap.        cmd.append('--dhcp-lease-max=%d' %                   min(possible_leases, self.conf.dnsmasq_lease_max))        cmd.append('--conf-file=%s' % self.conf.dnsmasq_config_file)        if self.conf.dnsmasq_dns_servers:            cmd.extend(                '--server=%s' % server                for server in self.conf.dnsmasq_dns_servers)

参考链接

http://www.cnblogs.com/sammyliu/p/5079898.html