https://blog.csdn.net/bc_vnetwork/article/details/53221061
QOS的配置
使系统支持qos的配置：
1.修改neutron-server的neutron.conf配置
# vim /etc/neutron/neutron.conf
service_plugins = neutron.services.qos.qos_plugin.QoSPlugin
2.修改neutron-server的ml2_conf.ini配置
# vim /etc/neutron/plugins/ml2/ml2_conf.ini
[ml2]
extension_drivers=qos
3.修改ovs-agent配置
# vim /etc/neutron/plugins/ml2/ml2_conf.ini
[agent]
extensions=qos
4.配置policy.json使所用用户都有使用qos策略的权利（以下配置均为默认，可不配置）
# vim /etc/neutron/policy.json
"get_policy": "rule:regular_user",
"create_policy": "rule:regular_user",
"update_policy": "rule:regular_user",
"delete_policy": "rule:regular_user",
"get_policy_bandwidth_limit_rule": "rule:regular_user",
//设置带宽限制的权限，默认只有管理员能够设置、删除带宽限速
"create_policy_bandwidth_limit_rule": "rule:admin_only",
"delete_policy_bandwidth_limit_rule": "rule:admin_only",
"update_policy_bandwidth_limit_rule": "rule:admin_only",
"get_rule_type": "rule:regular_user",
//设置dscp规则的权限，默认只有管理员能设置、删除dscp限速
"get_policy_dscp_marking_rule": "rule:regular_user",
"create_dscp_marking_rule": "rule:admin_only",
"delete_dscp_marking_rule": "rule:admin_only",
"update_dscp_marking_rule": "rule:admin_only",
"get_rule_type": "rule:regular_user",
5.重启neutron-server和ovs-agent
QOS使用
针对tcp
例1 为端口创建策略及带宽限速规则
# neutron qos-policy-create bw-limiter
Created a new policy:
+-----------------+--------------------------------------+
| Field | Value |
+-----------------+--------------------------------------+
| created_at | 2016-11-16T06:59:11Z |
| description | |
| id |7f951336-6ed8-4b1b-b93f-6491fbe855b0 |
| name | bw-limiter |
| revision_number | 1 |
| rules | |
| shared | False |
| tenant_id | f332909670c841abb78c2e30e8c50c68 |
| updated_at | 2016-11-16T06:59:11Z |
+-----------------+--------------------------------------+
# neutron qos-bandwidth-limit-rule-createbw-limiter --max-kbps 3000 --max-burst-kbps 300
Created a new bandwidth_limit_rule:
+----------------+--------------------------------------+
| Field | Value |
+----------------+--------------------------------------+
| id |530f4a1c-6711-4ca5-a374-1b869ad14b4c |
| max_burst_kbps | 300 |
| max_kbps | 3000 |
+----------------+--------------------------------------+
将策略与端口绑定：
# neutron port-update88101e57-76fa-4d12-b0e0-4fc7634b874a --qos-policy bw-limiter
Updated port:88101e57-76fa-4d12-b0e0-4fc7634b874a
取消端口的QOS策略：
# neutron port-update88101e57-76fa-4d12-b0e0-4fc7634b874a --no-qos-policy
Updated port:88101e57-76fa-4d12-b0e0-4fc7634b874a
在端口创建时指定QOS：
# neutron port-create port-name--qos-policy-id bw-limiter
例2 为网络创建QOS策略
所有建立在网络上的虚机都会受网络的qos限制，dhcp和虚拟路由器的端口不受限制。
# neutron net-update013328fd-9001-4bef-9c97-f97c5efc22cc --qos-policy bw-limiter
Updated network:013328fd-9001-4bef-9c97-f97c5efc22cc
针对IP报文
例3 DSCP
# neutron qos-policy-create dscp-marking
Created a new policy:
+-----------------+--------------------------------------+
| Field | Value |
+-----------------+--------------------------------------+
| created_at | 2016-11-17T07:25:51Z |
| description | |
| id |d787d85d-9012-48fc-adcc-aaf9f57540ed |
| name | dscp-marking |
| revision_number | 1 |
| rules | |
| shared | False |
| tenant_id | f332909670c841abb78c2e30e8c50c68 |
| updated_at | 2016-11-17T07:25:51Z |
+-----------------+--------------------------------------+
# neutron qos-dscp-marking-rule-createdscp-marking --dscp-mark 26
Created a new dscp_marking_rule:
+-----------+--------------------------------------+
| Field | Value |
+-----------+--------------------------------------+
| dscp_mark | 26 |
| id | 334ce934-2f60-4ff4-93cb-d4aa3b707973 |
+-----------+--------------------------------------+
# neutron port-update750901a3-70b3-4907-a52a-0025fac9d6c1 --qos-policy dscp-marking
Updated port:750901a3-70b3-4907-a52a-0025fac9d6c1
注：一个端口只能有一个qos策略；一个qos策略可以同时包含带宽规则和dscp规则；qos策略被绑定到端口后不可以直接删除。
QOS的原理
本节只介绍以ovs作为qos实现的底层软件，使用ovs-agent实现的neutron qos功能。
Neutron定义的qos规则类型：
VALID_RULE_TYPES =[RULE_TYPE_BANDWIDTH_LIMIT,
RULE_TYPE_DSCP_MARKING,
RULE_TYPE_MINIMUM_BANDWIDTH,
]
N版Ovs-agent支持前两中规则，其中带宽限速只实现了虚机的出方向(egress)限速。使用neutron qos-available-rule-types可以查看当前系统支持的规则类型。
# neutronqos-available-rule-types
+-----------------+
|type |
+-----------------+
|dscp_marking |
|bandwidth_limit |
+-----------------+
端口Dscp的实现原理
Ovs-agent通过修改ovs中的相应端口的流表规则，改变IP报文的dscp值，具体代码如下：
neutron/plugins/ml2/drivers/openvswitch/agent/extension_drivers/qos_driver.py
def update_dscp_marking(self, port, rule):
…………….
…………….
else:
for flow in flows:
actions = str(flow).partition("actions=")[2]
acts = actions.split(',')
# mod_nw_tos = modify type of service header
# This is the second byte of the IPv4 packet header.
# DSCP makes up the upper 6 bits of this header field.
actions = "mod_nw_tos:" + mark + ","
actions += ','.join([act for act in acts if "mod_nw_tos:" not in act])
self.br_int.mod_flow(reg2=0, in_port=port, table=0,
actions=actions)
端口带宽限速的实现原理
通过修改ovs上的端口的ingress_policing_rate和ingress_policing_burst属性值来实现虚机出方向的限速，实现代码如下：
neutron/plugins/ml2/drivers/openvswitch/agent/extension_drivers/qos_driver.py
def update_bandwidth_limit(self, port, rule):
………
self.br_int.create_egress_bw_limit_for_port(vif_port.port_name,
max_kbps,
max_burst_kbps)
neutron/agent/common/ovs_lib.py
class OVSBridge(BaseOVS):
def create_egress_bw_limit_for_port(self, port_name, max_kbps,
max_burst_kbps):
self._set_egress_bw_limit_for_port(port_name, max_kbps, max_burst_kbps)
def _set_egress_bw_limit_for_port(self, port_name, max_kbps,
max_burst_kbps):
with self.ovsdb.transaction(check_error=True) as txn:
txn.add(self.ovsdb.db_set('Interface', port_name,
('ingress_policing_rate', max_kbps)))
txn.add(self.ovsdb.db_set('Interface', port_name,
('ingress_policing_burst',max_burst_kbps)))
网络限速的实现原理
在N版中，用户可以为一个网络绑定一个qos策略，虚机如果创建在该网络上，那么虚机端口的network_qos_policy_id属性值等于该qos策略的id，同时ovs-agent会操作ovs，在底层根据qos策略进行相应操作。虚机在创建的过程中会由nova创建ovs的端口，这一操作会被ovs-agent捕获，在ovs-agent的rpc_loop过程中，会使用process_network_ports方法处理新增的端口。下面通过源码分析，解析使用网络限速功能后，ovs端口是如何被设置了qos策略。
Neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py
Class OVSNeutronAgent:
def process_network_ports(self, port_info, ovs_restarted):
……
if devices_added_updated:
start = time.time()
(skipped_devices, need_binding_devices,
security_disabled_ports, failed_devices['added']) = (
self.treat_devices_added_or_updated(
devices_added_updated, ovs_restarted))
def treat_devices_added_or_updated(self, devices, ovs_restarted):
…… ……
for details in devices:
…… ……
if 'port_id' in details:
…… ……
self.ext_manager.handle_port(self.context, details)
这里的ext_manager负责管理ovs-agent的额外插件，第一节配置中的qos就是其中的一个extension。
neutron/agent/l2/l2_agent_extensions_manager.py
class L2AgentExtensionsManager:
def handle_port(self, context, data):
"""Notify all agent extensions to handle port."""
for extension in self:
if hasattr(extension.obj, 'handle_port'):
extension.obj.handle_port(context, data)
neutron/agent/l2/extensions/qos.py
class QosAgentExtension:
def handle_port(self, context, port):
"""Handle agent QoS extension for port.
This method applies a new policy to a port using the QoS driver.
Update events are handled in _handle_notification.
"""
…… ……
至此，又会根据qos策略中包含的规则（带宽限速或dscp），对ovs进行相应的操作，从而实现了针对网络的限速。
总结
本文从配置、使用、原理三个方面介绍了N版的qos功能。在使用ovs作为qos的实现软件时，N版ovs-agent只能实现出方向的带宽限速和dscp限速。目前限速功能还不支持浮动IP限速。