Patent ID: 12231262

DETAILED DESCRIPTION

According to examples of the present disclosure, overlay networking may be implemented in an improved manner by dynamically mapping virtual tunnel endpoints (VTEPs) and virtualized computing instances (e.g., virtual machines). One example may involve a computer system (e.g., host-A110A inFIG.1) monitoring multiple VTEPs that are configured on the computer system for overlay networking, including a first VTEP (e.g., VTEP1181) and a second VTEP (e.g., VTEP2182). In response to detecting a state transition associated with the first VTEP from a HEALTHY state to an UNHEALTHY state, the computer system may identify mapping information that associates a virtualized computing instance (e.g., VM1131) with the first VTEP. Also, the mapping information may be updated to associate the virtualized computing instance with the second VTEP, thereby migrating the virtualized computing instance from the first VTEP (i.e., UNHEALTHY) to the second VTEP (i.e., HEALTHY).

In response to detecting an egress packet from the virtualized computing instance to a destination, an encapsulated packet (e.g.,192inFIG.1) may be generated and sent towards the destination based on the updated mapping information. The encapsulated packet may include the egress packet and an outer header identifying the second VTEP to be a source VTEP. As will be described below, mapping information may be updated dynamically and automatically to facilitate high-availability overlay networking, reduce system downtime, and improve data center user experience.

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the drawings, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

Challenges relating to overlay networking will now be explained in more detail usingFIG.1, which is a schematic diagram illustrating example software-defined networking (SDN) environment100in which VTEP mapping for overlay networking may be performed. It should be understood that, depending on the desired implementation, SDN environment100may include additional and/or alternative components than that shown inFIG.1. Although the terms “first” and “second” are used to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. For example, a first element may be referred to as a second element, and vice versa.

SDN environment100includes multiple hosts110A-B that are inter-connected via physical network105. Each host110A/110B may include suitable hardware112A/112B and virtualization software (e.g., hypervisor-A114A, hypervisor-B114B) to support various virtual machines (VMs). For example, hosts110A-B may support respective VMs131-134. Hardware112A/112B includes suitable physical components, such as central processing unit(s) or processor(s)120A/120B; memory122A/122B; physical network interface controllers (PNICs)171-174; and storage126A/126B, etc. In practice, SDN environment100may include any number of hosts (also known as “host computers”, “host devices”, “physical servers”, “server systems”, “transport nodes,” etc.). Each host may be supporting tens or hundreds of VMs.

Hypervisor114A/114B maintains a mapping between underlying hardware112A/112B and virtual resources allocated to respective VMs. Virtual resources are allocated to respective VMs131-134to support a guest operating system (OS; not shown for simplicity) and application(s)141-144. For example, the virtual resources may include virtual CPU, guest physical memory, virtual disk, virtual network interface controller (VNIC), etc. Hardware resources may be emulated using virtual machine monitors (VMMs). For example inFIG.1, VNICs161-164are virtual network adapters for VMs131-134, respectively, and are emulated by corresponding VMMs (not shown for simplicity) instantiated by their respective hypervisor at respective host-A110A and host-B110B. The VMMs may be considered as part of respective VMs, or alternatively, separated from the VMs. Although one-to-one relationships are shown, one VM may be associated with multiple VNICs (each VNIC having its own network address).

Although examples of the present disclosure refer to VMs, it should be understood that a “virtual machine” running on a host is merely one example of a “virtualized computing instance” or “workload.” A virtualized computing instance may represent an addressable data compute node (DCN) or isolated user space instance. In practice, any suitable technology may be used to provide isolated user space instances, not just hardware virtualization. Other virtualized computing instances may include containers (e.g., running within a VM or on top of a host operating system without the need for a hypervisor or separate operating system or implemented as an operating system level virtualization), virtual private servers, client computers, etc. Such container technology is available from, among others, Docker, Inc. The VMs may also be complete computational environments, containing virtual equivalents of the hardware and software components of a physical computing system.

The term “hypervisor” may refer generally to a software layer or component that supports the execution of multiple virtualized computing instances, including system-level software in guest VMs that supports namespace containers such as Docker, etc. Hypervisors114A-B may each implement any suitable virtualization technology, such as VMware ESX® or ESXi™ (available from VMware, Inc.), Kernel-based Virtual Machine (KVM), etc. The term “packet” may refer generally to a group of bits that can be transported together, and may be in another form, such as “frame,” “message,” “segment,” etc. The term “traffic” or “flow” may refer generally to multiple packets. The term “layer-2” may refer generally to a link layer or media access control (MAC) layer; “layer-3” to a network or Internet Protocol (IP) layer; and “layer-4” to a transport layer (e.g., using Transmission Control Protocol (TCP), User Datagram Protocol (UDP), etc.), in the Open System Interconnection (OSI) model, although the concepts described herein may be used with other networking models.

Hypervisor114A/114B implements virtual switch115A/115B and logical distributed router (DR) instance117A/117B to handle egress packets from, and ingress packets to, corresponding VMs. In SDN environment100, logical switches and logical DRs may be implemented in a distributed manner and can span multiple hosts. For example, logical switches that provide logical layer-2 connectivity, i.e., an overlay network, may be implemented collectively by virtual switches115A-B and represented internally using forwarding tables116A-B at respective virtual switches115A-B. Forwarding tables116A-B may each include entries that collectively implement the respective logical switches. Further, logical DRs that provide logical layer-3 connectivity may be implemented collectively by DR instances117A-B and represented internally using routing tables (not shown) at respective DR instances117A-B. The routing tables may each include entries that collectively implement the respective logical DRs.

Packets may be received from, or sent to, each VM via an associated logical port. For example, logical switch ports165-168(labelled “LSP1” to “LSP4”) are associated with respective VMs131-134. Here, the term “logical port” or “logical switch port” may refer generally to a port on a logical switch to which a virtualized computing instance is connected. A “logical switch” may refer generally to a software-defined networking (SDN) construct that is collectively implemented by virtual switches115A-B inFIG.1, whereas a “virtual switch” may refer generally to a software switch or software implementation of a physical switch. In practice, there is usually a one-to-one mapping between a logical port on a logical switch and a virtual port on virtual switch115A/115B. However, the mapping may change in some scenarios, such as when the logical port is mapped to a different virtual port on a different virtual switch after migration of the corresponding virtualized computing instance (e.g., when the source host and destination host do not have a distributed virtual switch spanning them).

Through virtualization of networking services in SDN environment100, logical networks (also referred to as overlay networks or logical overlay networks) may be provisioned, changed, stored, deleted, and restored programmatically without having to reconfigure the underlying physical hardware architecture. SDN controller103and SDN manager104are example network management entities in SDN environment100. One example of an SDN controller is the NSX controller component of VMware NSX® (available from VMware, Inc.) that operates on a central control plane (CCP). SDN controller103may be a member of a controller cluster (not shown for simplicity) that is configurable using SDN manager104operating on a management plane. Network management entity103/104may be implemented using physical machine(s), VM(s), or both. Logical switches, logical routers, and logical overlay networks may be configured using SDN controller103, SDN manager104, etc. To send or receive control information, a local control plane (LCP) agent (not shown) on host110A/110B may interact with SDN controller103via control-plane channel101/102.

Overlay Networking

Advances relating to SDN with overlay networking in the last decade has enabled relatively quick and easy deployment and management of substantially large-scale data centers, usually called Software Defined Data Centers (SDDCs). The scale of these SDDCs has been increasing rapidly, such as towards hundreds of hypervisors that are each capable of hosting hundreds of VMs. In general, overlay networking stretches a layer-2 network over an underlying layer-3 network. Any suitable overlay networking protocol(s) may be implemented, such as Virtual eXtensible Local Area Network (VXLAN), Stateless Transport Tunneling (STT), Generic Network Virtualization Encapsulation (GENEVE), Generic Routing Encapsulation (GRE), etc.

In practice, overlay networking protocols require overlay traffic from VMs to be encapsulated with an outer header with source and destination VTEPs. For example inFIG.1, hypervisor114A/114B may implement multiple VTEPs to encapsulate and decapsulate packets with an outer header (also known as a tunnel header) identifying a logical overlay network. In particular, hypervisor-A114A at host-A110A implements VTEP1181and VTEP2182, while hypervisor-B114B at host-B110B implements VTEP3183and VTEP4184. Encapsulated packets may be sent via a logical overlay tunnel established between a pair of VTEPs over physical network105, over which respective hosts110A-B are in layer-3 connectivity with one another. In other words, the logical overlay tunnel terminates at the VTEPs.

Some example logical overlay networks are shown inFIG.2, which is a schematic diagram illustrating example management plane view200of SDN environment100inFIG.1. Here, VM1131and VM4134are located on a first logical layer-2 segment associated with virtual network identifier (VNI)=5000 and connected to a first logical switch (see “LS1”201). VM2132and VM3133are located on a second logical layer-2 segment associated with VNI=6000 and connected to a second logical switch (see “LS2”202). With the growth of infrastructure-as-a-service (IaaS), logical overlay networks may be deployed to support multiple tenants. In this case, each logical overlay network may be designed to be an abstract representation of a tenant's network in SDN environment100. Depending on the desired implementation, a multi-tier topology may be used to isolate multiple tenants.

A logical DR (see “DR”205) connects logical switches201-202to facilitate communication among VMs131-134on different segments. See also logical switch ports “LSP7”203and “LSP8”204, and logical router ports “LRP1”207and “LRP2”208connecting DR205with logical switches201-202. Logical switch201/202may be implemented collectively by multiple hosts110A-B, such as using virtual switches115A-B and represented internally using forwarding tables116A-B. DR205may be implemented collectively by multiple transport nodes, such as using edge node206and hosts110A-B. For example, DR205may be implemented using DR instances117A-B and represented internally using routing tables (not shown) at respective hosts110A-B.

Edge node206(labelled “EDGE”) may implement one or more logical DRs and logical service routers (SRs), such as DR205and SR209inFIG.2. SR209may represent a centralized routing component that provides centralized stateful services to VMs131-134, such as IP address assignment using dynamic host configuration protocol (DHCP), network address translation (NAT), etc. EDGE206may be implemented using VM(s) and/or physical machines (“bare metal machines”), and capable of performing functionalities of a switch, router (e.g., logical service router), bridge, gateway, edge appliance, or any combination thereof. In practice, EDGE206may be deployed at the edge of a geographical site to facilitate north-south traffic to an external network, such as another data center at a different geographical site.

One of the challenges in SDN environment100is to maintain the availability of overlay networking to support packet forwarding to/from VMs131-134. These workloads require network connectivity to support various applications, such as web servers, databases, proxies, network functions, etc. However, with the increased use of overlay networking protocols, the complexity of SDN environment100also increases, which inevitably introduces more possible failure points. For example inFIG.1, multiple VTEPs181-182may be configured on host-A110A for overlay networking. Conventionally, VM(s) may be mapped to VTEP181/182that is responsible for packet encapsulation and decapsulation for the VM(s). When VTEP181/182fails, however, overlay networking connectivity for the VM(s) will be lost. This is especially problematic there is a large number (e.g., several hundreds) of VMs that are mapped to particular VTEP181/182.

VTEP Mapping for Overlay Networking

According to examples of the present disclosure, the health of VTEPs181-184may be monitored and VM-VTEP mapping information updated dynamically and automatically on host110A/110B to facilitate high-availability overlay networking. In more detail,FIG.3is a flowchart of example process300for a computer system to perform VTEP mapping for overlay networking in SDN environment100. Example process300may include one or more operations, functions, or actions illustrated by one or more blocks, such as310to360. The various blocks may be combined into fewer blocks, divided into additional blocks, and/or eliminated depending on the desired implementation. In the following, various examples will be explained using host110A as an example “computer system” and VM1131as an example “virtualized computing instance.”

At310inFIG.3, host-A110A may monitor multiple VTEPs that are configured on host-A110A for overlay networking, including first VTEP1181and second VTEP2182. At320,330and340, in response to detecting a state transition associated with first VTEP181from a HEALTHY state to an UNHEALTHY state, host-A110A may identify mapping information that associates VM1131with first VTEP1181and update the mapping information to associate VM1131with second VTEP2182instead. This has the effect of migrating VM1131from first VTEP1181in the UNHEALTHY state to second VTEP2182in the HEALTHY state.

At350and360inFIG.3, in response to detecting an egress packet VM1131to a destination, host-A110A may generate and send an encapsulated packet towards the destination based on the updated mapping information. In this case, the encapsulated packet includes the egress packet and an outer header identifying the second VTEP2182to be a source VTEP.

For example inFIGS.1-2, first encapsulated packet (see190) may be generated and sent based on mapping information=(VM1131, VTEP1181). In this case, first encapsulated packet190may include an outer header (O1) identifying source VTEP=VTEP1181. In response to detecting a state transition from the HEALTHY state to the UNHEALHTY state, the mapping information may be updated to (VM1131, VTEP2182). Based on the updated mapping information, second encapsulated packet (see192inFIGS.1-2) may be generated and sent towards destination VTEP3183on host-B110B. Second encapsulated packet192may include an outer header (O2) identifying source VTEP=VTEP2182instead of VTEP1181.

Depending on the desired implementation, initial mapping=(VM1131, VTEP1181) may be configured once VM1131is created or connected to a network based on any suitable teaming policy, such as load balancing based on a configuration parameter (e.g., VNIC Port ID, MAC address) associated with VM1131and a failover order associated with multiple VTEPs181-182. The initial mapping=(VM1, VTEP1) may be restored once connectivity via first VTEP1181has recovered. For example, in response to detecting a subsequent state transition associated with first VTEP1181from the UNHEALTHY state to the HEALTHY state, host-A110A may update the mapping information to reassociate VM1131with VTEP1181. This has the effect of migrating VM1131from second VTEP2182to first VTEP1181, both being in the HEALTHY state. This way, overlay networking traffic may be load balanced among VTEPs181-182on host-A110A.

As will be described further below, VTEP181/182may transition between a HEALTHY state and an UNHEALHTY state according to a state machine inFIG.6. In a first example, block320may involve detecting the state transition to a first UNHEALTHY state (e.g., IP_WAITING inFIG.6) in which first VTEP181has not been assigned with a valid IP address by a Dynamic Host Configuration Protocol (DHCP) server, or the lease of the IP address has expired. In a second example, first VTEP181may transition to a second UNHEALTHY state (e.g., BFD_DOWN inFIG.6) in which each and every overlay networking path via first VTEP1181is down. In a third example, first VTEP181may transition to a third UNHEALTHY state (e.g., ADMIN_DOWN inFIG.6) that is configured by a network administrator, such as for maintenance and troubleshooting purposes.

Examples of the present disclosure should be contrasted against conventional approaches that rely on static VM-VTEP mapping. In this case, when there is a failure affecting a VTEP, VMs mapped to the VTEP will be affected because all overlay traffic will be dropped. The loss of overlay networking connectivity is especially problematic for VMs are running critical workloads and/or when a large number of VMs (e.g., order of hundreds) are mapped to the VTEP. In some cases, a network administrator may have to intervene and restore connectivity, which is time consuming and inefficient. As will be described further below, connectivity loss and the need for manual intervention may be reduced using examples of the present disclosure. In enterprises and cloud operations, any improvement in the availability of overlay networking is important because every second of downtime may lead to huge losses and degraded user experience.

VTEP Configuration and Mapping

FIG.4is a flowchart of example detailed process400for VTEP mapping for overlay networking in SDN environment100. Example process400may include one or more operations, functions, or actions illustrated at410to460. The various operations, functions or actions may be combined into fewer blocks, divided into additional blocks, and/or eliminated depending on the desired implementation. The example inFIG.4will be explained usingFIG.5, which is a schematic diagram illustrating example500of VTEP mapping for overlay networking.

Examples of the present disclosure may be implemented any suitable software and/or hardware component(s) that will be collectively represented using VTEP mapping module118A/118B inFIG.1. Depending on the desired implementation, mapping module118A/118B may include (1) an interface sub-module to check the IP address assignment, (2) a monitoring sub-module to manage monitoring sessions established between VTEPs, (3) remap up/down sub-module(s) to update mapping information dynamically, etc. In relation to overlay networking, the following notations will be used below: SIP=source IP address, DIP=destination IP address, OUTER_SIP=outer source VTEP IP address in an outer header, OUTER_DIP=outer destination VTEP IP address in the outer header, etc.

(a) Multi-VTEP Configuration

Referring first toFIG.5, host-A110A may be configured with multiple (N) VTEPs for overlay networking. Each VTEP may be denoted as VTEFi, where i=1, . . . , N. For the case N=2, VTEP1181and VTEP2182are configured for overlay networking on host-A110A. In practice, VTEPs181-182may be created as ports on virtual switch115A. Like any other interface, VTEP181/182requires an IP address and a MAC address. For example, VTEP1181may be associated with (IP address=IP-VTEP1, MAC address=MAC-VTEP1, VTEP label=VTEP1) and VTEP2182with (IP address=IP-VTEP2, MAC address=MAC-VTEP2, VTEP label=VTEP2). To connect to physical network105, each VTEPi may be associated with an uplink (denoted as UPLINKi), such as UPLINK1 for VTEP1181and UPLINK2 for VTEP2182. See501-502inFIG.5.

As used herein, an “uplink” may represent a logical construct for a connection to a network. From the perspective of host110A/B, the term “uplink” may refer generally to a network connection from host110A/B via PNIC171/172/173/174to a physical network device (e.g., top-of-rack switch, spine switch, router) in physical network105. The term “downlink,” on the other hand, may refer to a connection from the physical network device to host110A/B. In practice, the mapping between an uplink and a PNIC may be one-to-one (i.e., one PNIC per uplink). Alternatively, a NIC teaming policy may be implemented to map multiple PNICs to one uplink. The term “NIC teaming” may refer to the grouping of multiple PNICs into one logical NIC.

(b) VM-VTEP Mapping

Referring also toFIG.4, at405, host-A110A may perform initial VM-VTEP mapping for VM1131and VM2132. For example, when VM1131is created and connected to a network, host-A110A may create a VNIC port on virtual switch115A for VNIC161of VM1131. Similarly, for VM2132, a VNIC port may be created on virtual switch115A for VNIC2162. VM1131and VM2132are connected to the same virtual switch115A via respective VNIC ports.

To be mappable to different VTEPs, each VM may be configured with multiple VNICs. Each VNIC may be associated with a single VTEP for overlay networking. The one-to-one mapping is to reduce the risk of, if not prevent, MAC flaps on remote hosts. For example, VM1131may be allocated with multiple VNICs (collectively represented as161inFIG.1), including a first VNIC that is mappable to VTEP1181and a second VNIC mappable to VTEP2182via virtual switch115A. Similar configuration may be made for VM2132on host-A110A, as well as VM3133and VM4134on host-B110B.

Next, a VTEP may be selected for VM131/132based on any suitable teaming policy. In the example inFIG.5, VM1131is mapped to VTEP1181(see510), and VM2132to VTEP2182(see520). Once determined, the VM-VTEP mapping or association may not change unless there is a change in the teaming policy, or a VTEP is added, removed, or marked as standby. Any suitable teaming policy may be used, such as load balancing based on a configuration parameter (e.g., VNIC port ID, VNIC MAC address) associated with VM131/132, failover order associated with multiple VTEPs181-182, etc. These example policies will be discussed below.

(1) In a first example, VTEP selection may be performed to achieve load balancing based on source VNIC port ID (denoted as VNICPortID) associated with VM131/132. In this case, VTEP selection may involve determining modulo operation: endpointID=VNICPortID % N. Here, N=number of VTEPs and endpointID=unique ID assigned to a VTEP. For example, the modulo operation maps VM131/132to either endpointID=0 assigned to VTEP1181or endpointID=1 assigned to VTEP2182.

(2) In a second example, VTEP selection may be performed to achieve load balancing based on source VNIC MAC address (MACAddr) associated with VM131/132. In this case, VTEP selection may involve determining modulo operation: endpointID=MACAddr % N. Here, the sixth octet of the MAC address may be used instead of the VNIC port ID to map VM131/132to either VTEP1181or VTEP2182.

(3) In a third example, VTEP selection may be performed based on a failover order associated with VTEPs181-182. For example, host-A110A may be configured with two active VTEPs181-182, as well as a standby VTEP (not shown). Once an active VTEP fails, the standby VTEP may switch to the active mode and take over.

VTEP State Machine

At410inFIG.4, host-A110A may monitor VTEPs181-182configured for overlay networking. Each VTEPi may be associated with a health status or state (denoted as STATE-i) that is either HEALTHY or UNHEALTHY. For example, block410may involve monitoring whether VTEP181/182is assigned with a valid IP address by a DHCP server, or a lease for the IP address has expired. Additionally or alternatively, block410may involve monitoring a path (also known as a logical overlay tunnel) between local VTEP181/182on host-A110A and remote VTEP183/184on host-B110B. See also411-412.

Any fault detection or continuity check protocol suitable for monitoring purposes may be used at block411. One example is Bidirectional Forwarding Detection (BFD) protocol hat is defined in the Internet Engineering Task Force (IETF) Request for Comments (RFC)5880, which is incorporated herein by reference. In overlay networking, BFD may be used between two VTEPs to detect failures in the underlay path between them. Using an asynchronous mode, for example, BFD packets may be generated and sent (e.g., using mapping module118A/118B) over a BFD session periodically.

Some example HEALTHY and UNHEALTHY states will be discussed usingFIG.6, which is a schematic diagram illustrating example VTEP state machine600. There are five states that a VTEP might be in: initialization state (see INIT601), normal operational state (see NORMAL602), awaiting IP address assignment state (see IP_WAITING603), BFD session down state (see BFD_DOWN604) and administrator-configured down state (see ADMIN_DOWN605). When created, VTEP181/182will be in state=INIT601.

VTEP181/182may be considered HEALTHY when operating in state=NORMAL602. Otherwise, VTEP181/182may be considered UNHEALTHY when in IP_WAITING603, BFD_DOWN604or ADMIN_DOWN605. In this case, host-A110A may detect the following state transitions:

At610inFIG.6, a state transition to INIT601from IP_WAITING603(i.e., UNHEALTHY) may be detected when a valid IP address is not assigned to VTEP181/182within a predetermined period of time (i.e., timeout period). The IP address assignment might fail for various reasons, such as a DHCP server being unreachable or running out of IP addresses available for assignment (e.g., due to server expansion).

At620inFIG.6, a state transition from INIT601to NORMAL602(i.e., HEALTHY) may be detected when a valid IP address is assigned to VTEP181/182and all its BFD sessions are up and running.

At630inFIG.6, a state transition from NORMAL602to IP_WAITING603(i.e., UNHEALTHY) may be detected when an IP address assigned to VTEP181/182is lost. In practice, when an IP address is assigned by the DHCP server, the IP address is leased for a specific amount of time called DHCP lease time. The IP address may be lost when the lease is not renewed, such as when DHCP server is unreachable or has run out of IP addresses.

At640inFIG.6, a state transition from NORMAL602to BFD_DOWN604(i.e., UNHEALTHY) may be detected when each and every overlay networking path and associated BFD session established using that VTEP181/182is down. For example, a full-mesh topology may be used to establish BFD sessions among VTEPs181-184. At host-A110A, for example, local VTEP1181may establish two BFD sessions with respective remote VTEP3183and VTEP4184on host-B110B. The state transition occurs when each and every BFD session is down. At641, a state transition from BFD_DOWN604to NORMAL602may occur when at least one BFD session is up, or there is an IP address change event. The IP address change may be detected when a new DHCP lease with a different IP address is given by a DHCP server during lease renewal, or an operator manually changes the VTEP IP address (e.g., using SDN manager103). Note that if there is at least one of the BFD sessions is up and running, VTEP1181remains in NORMAL602and no state transition to BFD_DOWN604will occur.

At650inFIG.6, a state transition from BFD_DOWN604to IP WAITING603(i.e., UNHEALTHY) may be detected when an IP address assigned to VTEP181/182is lost. Again, this may occur when the DHCP server becomes unreachable or has run out of IP addresses.

At660,670,680and690inFIG.6, a state transition to ADMIN_DOWN605(i.e., UNHEALTHY) from INIT601, NORMAL602, IP_WAITING603or BFD_DOWN604may be detected. ADMIN_DOWN605represents a state that is configured by a network administrator to bring VTEP181/182down, such as for maintenance and troubleshooting purposes. At681, a state transition from ADMIN_DOWN605to INIT601may occur when the network administrator performs configuration to bring VTEP181/182up and running again.

State Transitions

(a) HEALTHY to UNHEALTHY

At415-420inFIG.4, in response to detecting a state transition from HEALTHY to UNHEALTHY, host-A110A may update a VM-VTEP mapping after a timeout period. In practice, block415may involve a notification system generating system notifications relating to state transitions, and a remap module listening to the notifications to detect any faulty VTEP. The timeout period may be user-configurable to avoid unnecessary remapping due to transient faults. Once the timeout period has elapsed, at425, host-A110A may identify a HEALTHY VTEPk where k≠i and i, k ∈ {1, . . . , N}. This way, at430-435, each VM that is mapped to the UNHEALTHY VTEPi may be identified and migrated to the HEALTHY VTEPk.

In the example inFIG.5, both VTEP1181and VTEP2182may be detected to be HEALTHY (e.g., NORMAL602) at one point in time. In this case, host-A110A may configure mapping information identifying first mapping=(VM1131, VTEP1181) and second mapping=(VM2132, VTEP2182) according to any suitable teaming policy. See510-540inFIG.5.

After some time, however, host-A110A may detect a state transition associated with VTEP1181from HEALTHY (e.g., NORMAL602) to UNHEALTHY (e.g., IP_WAITING603). Once the timeout period has elapsed, host-A110A may identify VTEP2182to be in state=HEALTHY (e.g., NORMAL602) and update the mapping information to associate VM1131with VTEP2182. This has the effect of migrating VM1131from source=VTEP1181in the UNHEALTHY state to target=VTEP2182in the HEALTHY state. Since VTEP2182remains HEALTHY, the (VM2132, VTEP2182) mapping is not affected. See550(state transition),560(updated state) and570(updated mapping information) inFIG.5.

At440inFIG.4, once the VM-VTEP mapping is updated, host-A110A may generate and send a report to inform SDN controller104of the updated mapping information, such as (VM1131, VTEP2182) inFIG.5. The control information may be sent to cause SDN controller104to propagate the updated mapping information to remote hosts, including host-B110B to facilitate packet forwarding towards VM1131using destination VTEP2182instead of VTEP1181.

(b) UNHEALTHY to HEALTHY

At445-455inFIG.4, in response to detecting a state transition from UNHEALTHY to HEALTHY, host-A110A may restore a VM-VTEP mapping. In particular, at450, in response to detecting that VTEPi has recovered, host-A110A may identify VM(s) previously mapped to VTEPi and migrated to VTEPk. This way, at455, host-A110A may migrate the VM(s) from VTEPk to VTEPi for load balancing purposes. Further, at460, a report may be generated and sent to inform SDN controller104and trigger propagation of the updated mapping to other hosts, including host-B110B.

In the example inFIG.5, host-A110A may detect a state transition from UNHEALTHY (e.g., IP_WAITING603) to HEALTHY (e.g., NORMAL602) for VTEP181. In response, host-A110A may identify restore the first mapping to (VM1131, VTEP1181) assuming that the teaming policy has not changed and no new VTEP is added or removed. This has the effect of migrating VM1131from VTEP2182to VTEP1181. In practice, blocks410-460may be repeated as required as VTEP181/182alternates between HEALTHY and UNHEALTHY. See also550and580inFIG.5.

In practice, whenever mapping information is updated, host-A110A may generate and send a notification to management entity103/104, such as to alert a network administrator using a user interface provided by SDN manager103on the management plane. The user interface may also display VTEP state information and support administrative operations to transition to/from ADMIN_DOWN670state. In practice, the user interface may be a graphical user interface (GUI), command line interface (CLI), application programming interface (API), etc.

Overlay Networking

FIG.7is a schematic diagram illustrating example700of overlay traffic forwarding based on the mapping information inFIG.5. Any suitable tunneling protocol or encapsulation mechanism may be used for overlay networking, such as VXLAN, GENEVE, GRE, etc. The encapsulation mechanisms are generally connectionless. Using GENENE as an example, various implementation details may be found in a draft document entitled “GENEVE: Generic Network Virtualization Encapsulation” (draft-ietf-nvo3-geneve-16) published by Internet Engineering Task Force (IETF). The document is incorporated herein by reference.

At710and720inFIG.7, in response to detecting a first egress packet (P1) from VM1131to VM3133, a first encapsulated packet (O1, P1) may be generated based on mapping information=(VM1131, VTEP1181). In this case, VTEP1181is associated with state=HEALTHY (e.g., NORMAL). The egress packet (P1) may specify (SIP=IP-VM1, DIP=IP-VM3) associated with respective source VM1131on host-A110A and destination VM3133on host-B110B. The first encapsulated packet may include the egress packet (P1) and an outer header (O1) specifying specify (OUTER_SIP=IP-VTEP1, OUTER_DIP=IP-VTEP2) associated with respective source VTEP1181on host-A110A and destination VTEP3183on host-B110B.

At730inFIG.7, in response to receiving the first encapsulated packet, destination VTEP3183may perform decapsulation and forward the inner packet (P1) to VM3133. Based on mapping information=(VM1131, VTEP1181), any return traffic from VM3133to VM1131may be sent from VTEP3183on host-B110B to VTEP1181on host-A110A. Note that the source and destination VMs may be associated with the same VNI, or different VNIs. Using the example inFIG.2, VM1131and VM3133may be in different VNIs and connected via logical switches (e.g., LS1201and LS2202) and a logical router (e.g., DR205).

At740inFIG.7, in response to detecting a state transition associated with VTEP1181from HEALTHY to UNHEALTHY, host-A110A may update the mapping information to (VM1131, VTEP2182). Again, this has the effect of migrating VM1131from VTEP1181in the UNHEALTHY state (e.g., IP_WAITING, BFD_DOWN or ADMIN_DOWN) to VTEP2182in the HEALTHY state (e.g., NORMAL).

At750and760inFIG.7, in response to detecting a second egress packet (P2) from VM1131to VM3133, a second encapsulated packet (O2, P2) may be generated based on updated mapping information=(VM1131, VTEP2182). The second encapsulated packet may be generated by encapsulating the egress packet (P2) with an outer header (O2) specifying specify (OUTER_SIP=IP-VTEP2, OUTER_DIP=IP-VTEP2) associated with respective source VTEP2182on host-A110A and destination VTEP3183on host-B110B.

At770inFIG.7, in response to receiving the second encapsulated packet, destination VTEP3183may perform decapsulation and forward the inner packet (P2) to VM3133. Based on updated mapping information=(VM1131, VTEP2182) learned from the second encapsulated packet and/or received from SDN controller104, any return traffic from VM3133to VM1131may be sent from VTEP3183on host-B110B to VTEP2182on host-A110A.

Similar to the example inFIG.5, the mapping information may be updated dynamically based on the state of VTEP181/182. This reduces the likelihood of the connectivity loss for VM(s) mapped to particular VTEP1181based on a teaming policy. Instead of maintaining the mapping statically, the VM(s) may be migrated to facilitate high availability of overlay networking. This reduces system downtime and improves VM performance. Based on the above examples, automatic remapping of VMs to HEALTHY VTEPs may be performed to support high availability of overlay networking to improve VM performance and user experience.

Load Balancing

FIG.8is a schematic diagram illustrating second example800of VTEP mapping for overlay networking. In this example, multiple VMs may be migrated from a source VTEP to respective multiple destination VTEPs for load balancing purposes. For example, host-A110A may be configured with N=4 VTEPs for overlay networking, particularly VTEP-A1181, VTEP-A2182, VTEP-A3801and VTEP-A4802.

At810-840inFIG.8, host-A110A may generate mapping information that associates multiple VMs (i.e., VM1131, VM5135, VM6136and VM7137) with VTEP-A1181. Here, all VTEPs181-182,801-802are in state=HEALTHY and mapped to respective uplinks501-502,803-804.

At850inFIG.8, host-A110A may detect a state transition associated with VTEP-A1181from HEALTHY to UNHEALTHY (e.g., BFD_DOWN604inFIG.6). In response, host-A110A may update the mapping information to migrate VMs131,135-137from VTEP-A1181. For example, VM1131may be migrated to VTEP-A2182(see860), VM5135also to VTEP-A2182(see870), VM6136to VTEP-A3801(see880), and VM7137to VTEP-A4802(see890). This way, overlay traffic from these VMs may continue to flow while a network administrator fixes issues affecting VTEP-A1181.

In practice, the destination VTEP for each VM may be selected at random, and/or using a teaming policy. For example, VTEP selection may be performed to achieve load balancing based on a configuration parameter (e.g., VNICPortID or MACAddr) associated with VM131/135/136/137. Since there are N−1=3 VTEPs in state=HEALTHY for overlay networking, the following modulo operation may be performed to select VTEP-A2182, VTEP-A3801or VTEP-A4802: endpointID=(VNICPortID or MACAddr)% (N−1).

In another example, the VTEP selection may be load-based, such as based on the number of VMs that are already mapped to VTEP-A2182, VTEP-A3801or VTEP-A4802. This way, multiple (M=4) VMs requiring migration may be distributed among N−1=3 VTEPs that are operating in state=HEALTHY to reduce the risk of overloading a particular VTEP. Another example may involve tracking a performance metric (e.g., packet rate) on the uplinks and selecting a VTEP associated with a particular uplink with the least usage.

At895inFIG.8, when faulty VTEP-A1181is fixed and transitions into state=HEALTHY again, host-A110A may restore the initial mappings by migrating VMs131,135-137back to VTEP-A1181. Based on the above, examples of the present disclosure facilitate high-availability overlay networking to reduce downtime in SDN environment100.

Container Implementation

Although explained using VMs, it should be understood that public cloud environment100may include other virtual workloads, such as containers, etc. As used herein, the term “container” (also known as “container instance”) is used generally to describe an application that is encapsulated with all its dependencies (e.g., binaries, libraries, etc.). In the examples inFIG.1toFIG.8, container technologies may be used to run various containers inside respective VMs131-134. Containers are “OS-less”, meaning that they do not include any OS that could weigh 10s of Gigabytes (GB). This makes containers more lightweight, portable, efficient, and suitable for delivery into an isolated OS environment. Running containers inside a VM (known as “containers-on-virtual-machine” approach) not only leverages the benefits of container technologies but also that of virtualization technologies. The containers may be executed as isolated processes inside respective VMs.

Computer System

The above examples can be implemented by hardware (including hardware logic circuitry), software or firmware or a combination thereof. The above examples may be implemented by any suitable computing device, computer system, etc. The computer system may include processor(s), memory unit(s) and physical NIC(s) that may communicate with each other via a communication bus, etc. The computer system may include a non-transitory computer-readable medium having stored thereon instructions or program code that, when executed by the processor, cause the processor to perform process(es) described herein with reference toFIG.1toFIG.8.

The techniques introduced above can be implemented in special-purpose hardwired circuitry, in software and/or firmware in conjunction with programmable circuitry, or in a combination thereof. Special-purpose hardwired circuitry may be in the form of, for example, one or more application-specific integrated circuits (ASICs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), and others. The term ‘processor’ is to be interpreted broadly to include a processing unit, ASIC, logic unit, or programmable gate array etc.

The foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Insofar as such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those within the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or any combination thereof.

Those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computing systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure.

Software and/or to implement the techniques introduced here may be stored on a non-transitory computer-readable storage medium and may be executed by one or more general-purpose or special-purpose programmable microprocessors. A “computer-readable storage medium”, as the term is used herein, includes any mechanism that provides (i.e., stores and/or transmits) information in a form accessible by a machine (e.g., a computer, network device, personal digital assistant (PDA), mobile device, manufacturing tool, any device with a set of one or more processors, etc.). A computer-readable storage medium may include recordable/non recordable media (e.g., read-only memory (ROM), random access memory (RAM), magnetic disk or optical storage media, flash memory devices, etc.).

The drawings are only illustrations of an example, wherein the units or procedure shown in the drawings are not necessarily essential for implementing the present disclosure. Those skilled in the art will understand that the units in the device in the examples can be arranged in the device in the examples as described, or can be alternatively located in one or more devices different from that in the examples. The units in the examples described can be combined into one module or further divided into a plurality of sub-units.