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Overlap flow

Overlap flow

Owned by Tracy Yang
Nov 28, 2023

Because some limitation of ASIC, some flow installed hardware can not work as expected. User should refer to this chapter before user starts to trouble-shoot the issues. 

udp/ip, tcp/ip 

When user adds flows with the same priority, and one flow's match fields includes another flow's match fields, the action of flow is at random. For example:

 

admin@PicOS-OVS$ovs-ofctl add-flow br0 priority=10000,ip,in_port=14,dl_vlan=2,actions=push_vlan:0x8100,set_field:2503-\>vlan_vid,output:15
admin@PicOS-OVS$ovs-appctl pica/dump-flows 
#40 permanent priority=10000,ip,in_port=14,dl_vlan=2, actions:push_vlan(vid=2503),mod_vlan_pcp(pcp=0),15
Total 1 flows in TCAM.
admin@PicOS-OVS$ovs-ofctl add-flow br0 priority=10000,udp,in_port=14,dl_vlan=2,tp_dst=2123,actions=push_vlan:0x8100,set_field:2500-\>vlan_vid,output:15 
admin@PicOS-OVS$
admin@PicOS-OVS$ovs-appctl pica/dump-flows 
#41 permanent priority=10000,udp,in_port=14,dl_vlan=2,tp_dst=2123, actions:push_vlan(vid=2503),mod_vlan_pcp(pcp=0),15
#40 permanent priority=10000,ip,in_port=14,dl_vlan=2, actions:push_vlan(vid=2503),mod_vlan_pcp(pcp=0),15
Total 2 flows in TCAM.

If user doesn't want this result, user should modify the two flows' priorities.

admin@PicOS-OVS$ovs-ofctl add-flow br0 priority=12000,udp,in_port=14,dl_vlan=2,tp_dst=2123,actions=push_vlan:0x8100,set_field:2500-\>vlan_vid,output:15
ovs-ofctl add-flow br0 priority=10000,ip,in_port=14,dl_vlan=2,actions=push_vlan:0x8100,set_field:2503-\>vlan_vid,output:15
admin@PicOS-OVS$ovs-appctl pica/dump-flows 
#42 permanent priority=12000,udp,in_port=14,dl_vlan=2,tp_dst=2123, actions:push_vlan(vid=2500),mod_vlan_pcp(pcp=0),15
#40 permanent priority=10000,ip,in_port=14,dl_vlan=2, actions:push_vlan(vid=2503),mod_vlan_pcp(pcp=0),15
Total 2 flows in TCAM.

 

 

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