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Rudra Rugge edited this page Nov 14, 2016 · 7 revisions

#1. Introduction Add support for ecmp based loadbalancer in OpenContrail.

#2. Problem statement Currently OpenContrail supports L4-L7 proxy based loadbalancers. This is done by instantiating haproxy on a compute node. If there is no requirement for proxy based loadbalancers then ecmp based loadbalancing helps prevents traffic tromboning. ##2.1 Use cases In container orchestration systems such as Kubernetes there is a need to distribute traffic to PODS behind a service. Proxy based solutions are not distributed and add overhead for simple distribution of traffic to stateless PODS. Hence the native ECMP based solution is needed.

#3. Proposed solution OpenContrail supports ECMP based forwarding if the same IP address is announced by different endpoints. This is based on a hash of the five tuple:

  • Source ip
  • Source port
  • Destination ip
  • Desination port
  • Protocol

##3.1 Alternatives considered Proxy solutions are potential alternatives.

##3.2 API schema changes New loadbalancer provider called "native" is being added to the loadbalancer object. The rest of the objects remain the same as before in the loadbalancer hierarchy.

  • User creates a port for a virtual-ip.
  • User provides the list of endpoint IPs as members for the VIP.

##3.3 User workflow impact ####Set the configuration for provider as "native"

  • neutron net-create private-net
  • neutron subnet-create --name private-subnet private-net 30.30.30.0/24
  • neutron lbaas-loadbalancer-create $(neutron subnet-list | awk '/ private-subnet / {print $2}') --name lb1
  • neutron lbaas-listener-create --loadbalancer lb1 --protocol-port 80 --protocol HTTP --name listener1
  • neutron lbaas-pool-create --name pool1 --protocol HTTP --listener listener1 --lb-algorithm ROUND_ROBIN
  • neutron lbaas-member-create --subnet private-subnet --address 30.30.30.10 --protocol-port 8080 mypool
  • neutron lbaas-member-create --subnet private-subnet --address 30.30.30.11 --protocol-port 8080 mypool

##3.4 UI changes ####UI changes will be done to configure the loadbalancer

##3.5 Notification impact ####Logs, UVE and stats will be generated from the controller and agent.

#4. Implementation ##4.1 Assignee(s)

Yuvaraja Mariappan (Dev)

##4.2 Work items ###Controller changes

  • Controller now aggregates the configuration based on the provider. In the case of native provider controller allocates a new floating-ip object as the child of the instance-ip. It copies the IP address from the instance-ip into the floating-ip. Controller also copies the port translations from VIP to members in the floating-ip object. There is a flag to identify that port-translations are enabled on the floating-ip.
  • In addition controller also attaches this floating IP to all the virtual machine interface objects of the endpoints/pool members.

Agent changes

  • Agent acts on the new floating-ip object. Based on the port translation flag agent creates a port translation table for the floating ip. In addition agent traverses its parent instance-ip to get the corresponding routing table information.

#5. Performance and scaling impact ##5.1 API and control plane There is no impact on API and control plane performance.

##5.2 Forwarding performance Forwarding performance should be better than proxy based solutions but this needs to be characterized during the test cycle.

#6. Upgrade ####Describe upgrade impact of the feature The native loadbalancer is a new feature and hence does not have any upgrade impact.

#7. Deprecations

Not applicable

#8. Dependencies

Health check implementation for native loadbalancer depends on the following bluprint

https://blueprints.launchpad.net/opencontrail/+spec/service-health-check

#9. Testing ##9.1 Unit tests ##9.2 Dev tests ##9.3 System tests

#10. Documentation Impact

#11. References

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