sdn - Openflow交换机中同一个流有多个转发规则怎么办？

Question

我正在尝试使用 POX Controller 来控制流的路径。我知道 Open vSwitch 会选择具有最高优先级的转发规则。但是如果我为具有相同优先级的现有流插入新的转发规则会发生什么。 Open vSwitch 会随机选择一个规则来匹配吗？

Answer 1

OpenFlow 1.3 specification说:

If there are multiple matching flow entries with the same highest priority, the selected flow entry is explicitly undefined.

较旧的 OpenFlow 1.0 specification指出:

If multiple entries have the same priority, the switch is free to choose any ordering.

Open vSwitch docs和这个其他来源 here说:

OpenFlow leaves behavior undefined when two or more flows with the same priority can match a single packet. Some users expect "sensible" behavior, such as more specific flows taking precedence over less specific flows, but OpenFlow does not specify this and Open vSwitch does not implement it. Users should therefore take care to use priorities to ensure the behavior that they expect.

不清楚，我知道，但根据这些来源，由用户来处理发生具有相同优先级的流条目重叠的情况。用户应该注意设置正确的优先级，交换机可以按照供应商的要求自由实现处理此问题的方法。例如，交换机可能会选择最新的流条目，正如您所说的那样。