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Flows are setup in pipeline processing model as depicted in below diagram, to emulate packet processing on the VPC VR. A default rule with least priority (0) is set in egress ACL's table to forward drop all packets to lookup table. Flow rules are added to egress ACL table with high priority (to overrider default rule) to drop forward packets corresponding to lookup table corresponding to egress network ACL's for the tier. Route look up is done in table 1 which is pre populated to resubmit to next level ingress ACL table depending on the destination subnet. A default rule with least priority (0) is set in ingress ACL's table to output packets drop all ingress traffic to a port. Flow rules are added to ingress ACL table with high priority (to overrider default rule) to drop permit packets corresponding to ingree ingress network ACL's for the tier.
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Lets assume tier1, tier 2 and tier3 has subnets 10.1.1.0/24, 10.1.2.0/24 and 10.1.3.0/24 respectively . and corresponding bridges for the tiers are connected to logical routers on openflow ports 1,2,3, flow table would look like below with no ingress and egress rules configured.
table=0,in_port=1 actions=resubmit(,2)
table=0,in_port=2 actions=resubmit(,3)
table=0,in_port=3 actions=resubmit(,4)
table=2, priority=0 actions=drop
table=3, priority=0 actions=drop
table=4, priority=0 actions=drop
table=1,priority=0,nw_dst=10.1.1.0/24 actions=resubmit(,5)
table=1,priority=0,nw_dst=10.1.2.0/24 actions=resubmit(,6)
table=1,priority=0,nw_dst=10.1.3.0/24 actions=resubmit(,7)
table=5, priority=0 actions=drop
table=6, priority=0 actions=drop
table=7, priority=0 actions=drop
Assuming a ingress ACL to permit traffic from tier2, and egress ACL to permit outbound traffic to tier is applied on tier 1 network, below new rules will be added in to flow table of the bridge.
table=2, priority=1000,nw_dst=10.1.2.0/24 actions=resubmit(,1)
table=5, priority=1000,nw_src=10.1.2.0/24 actions=output:1
Fall back approach:
Achieving distributed routing and network ACL, would need distributed configuration. Given the scale of changes that would involve
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