OVS流表table之间的跳转

OVS流表table之间的跳转

前言

今天在帮学弟解决问题的时候，遇到一个table0、table1之间的微妙小插曲，引起了注意，后来查了一下资料发现原因了。

问题描述

wpq@wpq:~$ sudo ovs-ofctl dump-flows -O OpenFlow13 s1

OFPST_FLOW reply (OF1.3) (xid=0x2):
 cookie=0x0, duration=275.673s, table=0, n_packets=22, n_bytes=2156, priority=1000,ip,nw_src=10.0.0.2,nw_dst=10.0.0.1 actions=output:1
 cookie=0x0, duration=285.517s, table=0, n_packets=16, n_bytes=672, priority=1000,arp actions=FLOOD
 cookie=0x0, duration=53.643s, table=1, n_packets=0, n_bytes=0, priority=1000,ip,nw_src=10.0.0.1,nw_dst=10.0.0.2 actions=output:2

如上输出所示，位于table1的流表的n_packet始终无法上涨，说明流表始终没有被匹配到。

问题解决

还是自己太年轻，把最基本的openflow协议都给忘了，流表之间的跳转是要action的
OVS流表分析
上述链接中有句话引到

流表间的跳转并没有用标准OpenFlow规范中的指令GOTO_TABLE，而是使用了Nicira(开发ＯＶＳ的公司)的扩展动作resubmit

所以可以用两种方法

1、resubmit

wpq@wpq:~$ sudo ovs-ofctl -O OpenFlow13 add-flow s1 "table=0,priority=0,idle_timeout=0,actions=resubmit(,1)"

wpq@wpq:~$ sudo ovs-ofctl dump-flows -O OpenFlow13 s1

OFPST_FLOW reply (OF1.3) (xid=0x2):
 cookie=0x0, duration=2.370s, table=0, n_packets=0, n_bytes=0, priority=0 actions=resubmit(,1)
 cookie=0x0, duration=1139.038s, table=0, n_packets=23, n_bytes=2254, priority=1000,ip,nw_src=10.0.0.2,nw_dst=10.0.0.1 actions=output:1
 cookie=0x0, duration=1148.882s, table=0, n_packets=16, n_bytes=672, priority=1000,arp actions=FLOOD
 cookie=0x0, duration=917.008s, table=1, n_packets=0, n_bytes=0, priority=1000,ip,nw_src=10.0.0.1,nw_dst=10.0.0.2 actions=output:2

2、goto_table

wpq@wpq:~$ sudo ovs-ofctl -O OpenFlow13 add-flow s1 "table=0,priority=0,idle_timeout=0,actions=goto_table=1"

wpq@wpq:~$ sudo ovs-ofctl dump-flows -O OpenFlow13 s1 

OFPST_FLOW reply (OF1.3) (xid=0x2):
 cookie=0x0, duration=6.110s, table=0, n_packets=0, n_bytes=0, priority=0 actions=goto_table:1
 cookie=0x0, duration=101.774s, table=0, n_packets=0, n_bytes=0, priority=1000,ip,nw_src=10.0.0.2,nw_dst=10.0.0.1 actions=output:1
 cookie=0x0, duration=94.002s, table=0, n_packets=0, n_bytes=0, priority=1000,arp actions=FLOOD
 cookie=0x0, duration=1745.115s, table=1, n_packets=4, n_bytes=392, priority=1000,ip,nw_src=10.0.0.1,nw_dst=10.0.0.2 actions=output:2