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authorfuqiao <fuqiao@chinamobile.com>2016-01-28 10:05:33 +0800
committerfuqiao <fuqiao@chinamobile.com>2016-01-28 10:05:33 +0800
commitc3d65029c1f07fd11c5ec754b194ac1357b8e0ce (patch)
tree1353e16ebffe84ae16e914c263ae7f6aa3919dc4 /Scenario_1/Scenario_Analysis_Communication_Interfaces.rst
parent96ea75a56d8bc93a51cbd8a6ecffdcc5456e3d8b (diff)
Remove all the old seperate sections. Will Reorganize and upload again
Will upload the seperate sections in the next patch. JIRA:HA-1
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-3. Communication Interfaces for VNF HA schemes
-===========================================================
-
-This section will discuss some general issues about communication interfaces
-in the VNF HA schemes. In sections 2, the usecases of both stateful and
-stateless VNFs are discussed. While in this section, we would like to discuss
-some specific issues which are quite general for all the usecases proposed
-in the previous sections.
-
-3.1. VNF External Interfaces
-
-Regardless whether the VNF is stateful or stateless, all the VNFCs should act as
-a union from the perspective of the outside world. That means all the VNFCs should
-share a common interface where the outside modules (e.g., the other VNFs) can
-access the service from. There could be multiple solutions for this share of IP
-interface. However, all of this sharing and switching of IP address should be
-ignorant to the outside modules.
-
-There are several approaches for the VNFs to share the interfaces. A few of them
-are listed as follows and will be discussed in detail.
-
-1) IP address of VMs for active/stand-by VM.
-
-2) Load balancers for active/active use cases
-
-Note that combinition of these two approaches is also feasible.
-
-For active/standby VNFCs, there is a common IP address shared by the VMs hosting
-the active and standby VNFCs, so that they look as one instance from outside.
-The HA manager will manage the assignment of the IP address to the VMs.
-(The HA manager may not be aware of this, I.e. the address may be configured
-and the active/standby state management is linked to the possession of the IP
-address, i.e. the active VNFC claims it as part of becoming active.) Only the
-active one possesses the IP address. And when failover happens, the standby
-is set to be active and can take possession of the IP address to continue traffic
-process.
-
-
-For active/active VNFCs, a LB(Load Balancer) could be used. In such scenario, there
-could be two cases for the deployment and usage of LB.
-
-Case 1: LB used in front of a cluster of VNFCs to distribute the traffic flow.
-
-In such case, the LB is deployed in front of a cluster of multiple VNFCs. Such
-cluster can be managed by a seperate cluster manager, or can be managed just
-by the LB, which uses heartbeat to monitor each VNFC. When one of VNFCs fails,
-the cluster manager should first exclude the failed VNFC from the cluster so that
-the LB will re-route the traffic to the other VNFCs, and then the failed one should
-be recovered. In the case when the LB is acting as the cluster manager, it is
-the LB's responsibility to inform the VNFM to recover the failed VNFC if possible.
-
-
-Case 2: LB used in front of a cluster of VMs to distribute traffic flow.
-
-In this case, there exists a cluster manager(e.g. Pacemaker) to monitor and manage
-the VMs in the cluster. The LB sits in front of the VM cluster so as to distribute
-the traffic. When one of the VM fails, the cluster manager will detect that and will
-be in charge of the recovery. The cluster manager will also exclude the failed VM
-out of the cluster, so that the LB won't route traffic to the failed one.
-
-In both two cases, the HA of the LB should also be considered.
-
-
-3.2. Intra-VNF Communication
-
-For stateful VNFs, data synchronization is necessary between the active and standby VMs.
-The HA manager is responsible for handling VNFC failover, and do the assignment of the
-active/standby states between the VNFCs of the VNF. Data synchronization can be handled
-either by the HA manager or by the VNFC itself.
-
-The state synchronization can happen as
-
-- direct communication between the active and the standby VNFCs
-
-- based on the information received from the HA manager on channel or messages using a common queue,
-
-- it could be through a shared storage assigned to the whole VNF
-
-- through the checkpointing of state information via underlying memory and/or
-database checkpointing services to a separate VM and storage repository.