NVO3 Working Group                                                 Y. Li
INTERNET-DRAFT                                               D. Eastlake
Intended Status: Informational                       Huawei Technologies
                                                              L. Kreeger
                                                             Arrcus, Inc
                                                               T. Narten
                                                                D. Black
                                                                Dell EMC
Expires: August 29, September 14, 2018                               February 25,                               March 13, 2018

Split Network Virtualization Edge (Split-NVE) Control Plane Requirements


   In a Split Network Virtualization Edge (Split-NVE) architecture, the
   functions of the NVE (Network Virtualization Edge) are split across a
   server and an external network equipment which is called an external
   NVE.  The server-resident control plane functionality resides in
   control software, which may be part of hypervisor or container
   management software; for simplicity, this document refers to the
   hypervisor as the location of this software.

   Control plane protocol(s) between a hypervisor and its associated
   external NVE(s) are used by the hypervisor to distribute its virtual
   machine networking state to the external NVE(s) for further handling.
   This document illustrates the functionality required by this type of
   control plane signaling protocol and outlines the high level
   requirements. Virtual machine states as well as state transitioning
   are summarized to help clarify the protocol requirements.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  5
     1.2  Target Scenarios  . . . . . . . . . . . . . . . . . . . . .  6
   2. VM Lifecycle  . . . . . . . . . . . . . . . . . . . . . . . . .  8
     2.1 VM Creation Event  . . . . . . . . . . . . . . . . . . . . .  8
     2.2 VM Live Migration Event  . . . . . . . . . . . . . . . . . .  9
     2.3 VM Termination Event . . . . . . . . . . . . . . . . . . . . 10
     2.4 VM Pause, Suspension and Resumption Events . . . . . . . . . 10
   3. Hypervisor-to-NVE Control Plane Protocol Functionality  . . . . 11
     3.1 VN Connect and Disconnect  . . . . . . . . . . . . . . . . . 11
     3.2 TSI Associate and Activate . . . . . . . . . . . . . . . . . 13
     3.3 TSI Disassociate and Deactivate  . . . . . . . . . . . . . . 15
   4. Hypervisor-to-NVE Control Plane Protocol Requirements . . . . . 16
   5. VDP Applicability and Enhancement Needs . . . . . . . . . . . . 17
   6. Security Considerations . . . . . . . . . . . . . . . . . . . . 19
   7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 20
   8. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 20
   8. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 20
     8.1  Normative References  . . . . . . . . . . . . . . . . . . . 20
     8.2  Informative References  . . . . . . . . . . . . . . . . . . 21
   Appendix A. IEEE 802.1Q VDP Illustration (For information only)  . 21
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23 24

1.  Introduction

   In the Split-NVE architecture shown in Figure 1, the functionality of
   the NVE (Network Virtualization Edge) is split across an end device
   supporting virtualization and an external network device which is
   called an external NVE. The portion of the NVE functionality located
   on the end device is called the tNVE (terminal-side NVE) and the
   portion located on the external NVE is called the nNVE (network-side
   NVE) in this document. Overlay encapsulation/decapsulation functions
   are normally off-loaded to the nNVE on the external NVE.

   The tNVE is normally implemented as a part of hypervisor or container
   and/or virtual switch in an virtualized end device. This document
   uses the term "hypervisor" throughout when describing the Split-NVE
   scenario where part of the NVE functionality is off-loaded to a
   separate device from the "hypervisor" that contains a VM (Virtual
   Machine) connected to a VN (Virutal Network). In this context, the
   term "hypervisor" is meant to cover any device type where part of the
   NVE functionality is off-loaded in this fashion, e.g.,a Network
   Service Appliance or Linux Container.

   The NVO3 problem statement [RFC7364], discusses the needs for a
   control plane protocol (or protocols) to populate each NVE with the
   state needed to perform the required functions. In one scenario, an
   NVE provides overlay encapsulation/decapsulation packet forwarding
   services to Tenant Systems (TSs) that are co-resident within the NVE
   on the same End Device (e.g. when the NVE is embedded within a
   hypervisor or a Network Service Appliance). In such cases, there is
   no need for a standardized protocol between the hypervisor and NVE,
   as the interaction is implemented via software on a single device.
   While in the Split-NVE architecture scenarios, as shown in figure 2
   to figure 4, control plane protocol(s) between a hypervisor and its
   associated external NVE(s) are required for the hypervisor to
   distribute the virtual machines networking states to the NVE(s) for
   further handling. The protocol is an NVE-internal protocol and runs
   between tNVE and nNVE logical entities. This protocol is mentioned in
   the NVO3 problem statement [RFC7364] and appears as the third work

   Virtual machine states and state transitioning are summarized in this
   document showing events where the NVE needs to take specific actions.
   Such events might correspond to actions the control plane signaling
   protocol(s) need to take between tNVE and nNVE in the Split-NVE
   scenario. The high level requirements to be fulfilled are stated.

                       +------------ Split-NVE ---------+
                       |                                |
                       |                                |
     +-----------------|-----+                          |
     | +---------------|----+|                          |
     | | +--+         \|/   ||                          |
     | | |V |TSI  +-------+ ||                   +------|-------------+
     | | |M |-----+       | ||                   |     \|/            |
     | | +--+     |       | ||                   |+--------+          |
     | | +--+     | tNVE  | ||-------------------||        |          |
     | | |V |TSI  |       | ||                   || nNVE   |          |
     | | |M |-----|       | ||                   ||        |          |
     | | +--+     +-------+ ||                   |+--------+          |
     | |                    ||                   +--------------------+
     | +-----Hypervisor-----+|
            End Device                               External NVE

                        Figure 1 Split-NVE structure

   This document uses VMs as an example of Tenant Systems (TSs) in order
   to describe the requirements, even though a VM is just one type of
   Tenant System that may connect to a VN. For example, a service
   instance within a Network Service Appliance is another type of TS, as
   are systems running on an OS-level virtualization technologies like
   containers.  The fact that VMs have lifecycles (e.g., can be created
   and destroyed, can be moved, and can be started or stopped) results
   in a general set of protocol requirements, most of which are
   applicable to other forms of TSs although not all of the requirements
   are applicable to all forms of TSs.

   Section 2 describes VM states and state transitioning in the VM's
   lifecycle. Section 3 introduces Hypervisor-to-NVE control plane
   protocol functionality derived from VM operations and network events.
   Section 4 outlines the requirements of the control plane protocol to
   achieve the required functionality.

1.1  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   This document uses the same terminology as found in [RFC7365]. This
   section defines additional terminology used by this document.

   Split-NVE: a type of NVE (Network Virtualization Edge) where the
   functionalities are split across an end device supporting
   virtualization and an external network device.

   tNVE: the portion of Split-NVE functionalities located on the end
   device supporting virtualization. It interacts with a tenant system
   through an internal interface in the end device.

   nNVE: the portion of Split-NVE functionalities located on the network
   device that is directly or indirectly connected to the end device
   holding the corresponding tNVE. nNVE normally performs encapsulation
   to and decapsulation from the overlay network.

   External NVE: the physical network device holding the nNVE

   Hypervisor: the logical collection of software, firmware and/or
   hardware that allows the creation and running of server or service
   appliance virtualization. tNVE is located under a Hypervisor.
   Hypervisor is loosely used in this document to refer to the end
   device supporting the virtualization. For simplicity, we also use
   Hypervisor to represent both hypervisor and container.

   Container: Please refer to Hypervisor. For simplicity this document
   use the term hypervisor to represent both hypervisor and container.

   VN Profile:  Meta data associated with a VN (Virtual Network) that is
   applied to any attachment point to the VN. That is, VAP (Virtual
   Access Point) properties that are applied to all VAPs associated with
   a given VN and used by an NVE when ingressing/egressing packets
   to/from a specific VN.  Meta data could include such information as
   ACLs, QoS settings, etc. The VN Profile contains parameters that
   apply to the VN as a whole.  Control protocols between the NVE and
   NVA (Network Virtualization Authority) could use the VN ID or VN Name
   to obtain the VN Profile.

   VSI: Virtual Station Interface. [IEEE 802.1Q]

   VDP: VSI Discovery and Configuration Protocol [IEEE 802.1Q]

1.2  Target Scenarios

   In the Split-NVE architecture, an external NVE can provide an offload
   of the encapsulation / decapsulation functions and network policy
   enforcement as well as the VN Overlay protocol overhead.  This
   offloading may improve performance and/or save resources in the End
   Device (e.g. hypervisor) using the external NVE.

   The following figures give example scenarios of a Split-NVE

              Hypervisor             Access Switch
         +------------------+       +-----+-------+
         | +--+   +-------+ |       |     |       |
         | |VM|---|       | | VLAN  |     |       |
         | +--+   | tNVE  |---------+ nNVE|       +--- Underlying
         | +--+   |       | | Trunk |     |       |    Network
         | |VM|---|       | |       |     |       |
         | +--+   +-------+ |       |     |       |
         +------------------+       +-----+-------+
               Figure 2 Hypervisor with an External NVE

              Hypervisor      L2 Switch
         +---------------+     +-----+     +----+---+
         | +--+   +----+ |     |     |     |    |   |
         | |VM|---|    | |VLAN |     |VLAN |    |   |
         | +--+   |tNVE|-------+     +-----+nNVE|   +--- Underlying
         | +--+   |    | |Trunk|     |Trunk|    |   | Network
         | |VM|---|    | |     |     |     |    |   |
         | +--+   +----+ |     |     |     |    |   |
         +---------------+     +-----+     +----+---+
          Figure 3 Hypervisor with an External NVE
                   connected through an Ethernet Access Switch

          Network Service Appliance         Access Switch
         +--------------------------+      +-----+-------+
         | +------------+    | \    |      |     |       |
         | |Net Service |----|  \   |      |     |       |
         | |Instance    |    |   \  | VLAN |     |       |
         | +------------+    |tNVE| |------+nNVE |       +--- Underlying
         | +------------+    |    | | Trunk|     |       |    Network
         | |Net Service |----|   /  |      |     |       |
         | |Instance    |    |  /   |      |     |       |
         | +------------+    | /    |      |     |       |
         +--------------------------+      +-----+-------+
       Figure 4 Physical Network Service Appliance with an External NVE

   Tenant Systems connect to external NVEs via a Tenant System Interface
   (TSI).  The TSI logically connects to the external NVE via a Virtual
   Access Point (VAP) [RFC8014]. The external NVE may provide Layer 2 or
   Layer 3 forwarding. In the Split-NVE architecture, the external NVE
   may be able to reach multiple MAC and IP addresses via a TSI. An IP
   address can be in either IPv4 or IPv6 format. For example, Tenant
   Systems that are providing network services (such as transparent
   firewall, load balancer, or VPN gateway) are likely to have a complex
   address hierarchy. This implies that if a given TSI disassociates
   from one VN, all the MAC and/or IP addresses are also disassociated.
   There is no need to signal the deletion of every MAC or IP when the
   TSI is brought down or deleted. In the majority of cases, a VM will
   be acting as a simple host that will have a single TSI and single MAC
   and IP visible to the external NVE.

   Figures 2 through 4 show the use of VLANs to separate traffic for
   multiple VNs between the tNVE and nNVE; VLANs are not strictly
   necessary if only one VN is involved, but multiple VNs are expected
   in most cases. Hence this draft assumes the presence of VLANs.

2. VM Lifecycle

   Figure 2 of [RFC7666] shows the state transition of a VM. Some of the
   VM states are of interest to the external NVE. This section
   illustrates the relevant phases and events in the VM lifecycle. Note
   that the following subsections do not give an exhaustive traversal of
   VM lifecycle state. They are intended as the illustrative examples
   which are relevant to Split-NVE architecture, not as prescriptive
   text; the goal is to capture sufficient detail to set a context for
   the signaling protocol functionality and requirements described in
   the following sections.

2.1 VM Creation Event

   The VM creation event causes the VM state transition from Preparing
   to Shutdown and then to Running [RFC7666]. The end device allocates
   and initializes local virtual resources like storage in the VM
   Preparing state. In the Shutdown state, the VM has everything ready
   except that CPU execution is not scheduled by the hypervisor and VM's
   memory is not resident in the hypervisor.  The transition from the
   Shutdown state to the Running state normally requires human action or
   a system triggered event. Running state indicates the VM is in the
   normal execution state. As part of transitioning the VM to the
   Running state, the hypervisor must also provision network
   connectivity for the VM's TSI(s) so that Ethernet frames can be sent
   and received correctly. Initially, when Running, no ongoing
   migration, suspension or shutdown is in process.

   In the VM creation phase, the VM's TSI has to be associated with the
   external NVE. Association here indicates that hypervisor and the
   external NVE have signaled each other and reached some agreement.
   Relevant networking parameters or information have been provisioned
   properly. The External NVE should be informed of the VM's TSI MAC
   address and/or IP address. In addition to external network
   connectivity, the hypervisor may provide local network connectivity
   between the VM's TSI and other VM's TSI that are co-resident on the
   same hypervisor. When the intra- or inter-hypervisor connectivity is
   extended to the external NVE, a locally significant tag, e.g. VLAN
   ID, should be used between the hypervisor and the external NVE to
   differentiate each VN's traffic. Both the hypervisor and external NVE
   sides must agree on that tag value for traffic identification,
   isolation, and forwarding.

   The external NVE may need to do some preparation before it signals
   successful association with the TSI. Such preparation may include
   locally saving the states and binding information of the tenant
   system interface and its VN, communicating with the NVA for network
   provisioning, etc.

   Tenant System interface association should be performed before the VM
   enters the Running state, preferably in the Shutdown state. If
   association with an external NVE fails, the VM should not go into the
   Running state.

2.2 VM Live Migration Event

   Live migration is sometimes referred to as "hot" migration in that,
   from an external viewpoint, the VM appears to continue to run while
   being migrated to another server (e.g., TCP connections generally
   survive this class of migration).  In contrast, "cold" migration
   consists of shutting down VM execution on one server and restarting
   it on another. For simplicity, the following abstract summary of live
   migration assumes shared storage, so that the VM's storage is
   accessible to the source and destination servers. Assume VM live
   migrates from hypervisor 1 to hypervisor 2. Such a migration event
   involves state transitions on both source hypervisor 1 and
   destination hypervisor 2. The VM state on source hypervisor 1
   transits from Running to Migrating and then to Shutdown [RFC7666].
   The VM state on destination hypervisor 2 transits from Shutdown to
   Migrating and then Running.

   The external NVE connected to destination hypervisor 2 has to
   associate the migrating VM's TSI with it by discovering the TSI's MAC
   and/or IP addresses, its VN, locally significant VLAN ID if any, and
   provisioning other network related parameters of the TSI. The
   external NVE may be informed about the VM's peer VMs, storage devices
   and other network appliances with which the VM needs to communicate
   or is communicating. The migrated VM on destination hypervisor 2
   should not go to Running state until all the network provisioning and
   binding has been done.

   The states of VM on the source and destination hypervisors both are
   Migrating during transfer of migration execution. The migrating VM
   should not be in Running state at the same time on the source
   hypervisor and destination hypervisor during migration. The VM on the
   source hypervisor does not transition into Shutdown state until the
   VM successfully enters the Running state on the destination
   hypervisor. It is possible that the VM on the source hypervisor stays
   in Migrating state for a while after the VM on the destination
   hypervisor enters Running state.

2.3 VM Termination Event

   A VM termination event is also referred to as "powering off" a VM. A
   VM termination event leads to its state becoming Shutdown. There are
   two possible causes of VM termination [RFC7666]. One is the normal
   "power off" of a running VM; the other is that the VM has been
   migrated to another hypervisor and the VM image on the source
   hypervisor has to stop executing and be shutdown.

   In VM termination, the external NVE connecting to that VM needs to
   deprovision the VM, i.e. delete the network parameters associated
   with that VM. In other words, the external NVE has to de-associate
   the VM's TSI.

2.4 VM Pause, Suspension and Resumption Events

   A VM pause event leads to the VM transiting from Running state to
   Paused state. The Paused state indicates that the VM is resident in
   memory but no longer scheduled to execute by the hypervisor
   [RFC7666]. The VM can be easily re-activated from Paused state to
   Running state.

   A VM suspension event leads to the VM transiting from Running state
   to Suspended state. A VM resumption event leads to the VM transiting
   state from Suspended state to Running state. Suspended state means
   the memory and CPU execution state of the virtual machine are saved
   to persistent store.  During this state, the virtual machine is not
   scheduled to execute by the hypervisor [RFC7666].

   In the Split-NVE architecture, the external NVE should not
   disassociate the paused or suspended VM as the VM can return to
   Running state at any time.

3. Hypervisor-to-NVE Control Plane Protocol Functionality

   The following subsections show illustrative examples of the state
   transitions of an external NVE which are relevant to Hypervisor-to-
   NVE Signaling protocol functionality. It should be noted this is not
   prescriptive text for the full state machine.

3.1 VN Connect and Disconnect

   In the Split-NVE scenario, a protocol is needed between the End
   Device (e.g. Hypervisor) and the external NVE it is using in order to
   make the external NVE aware of the changing VN membership
   requirements of the Tenant Systems within the End Device.

   A key driver for using a protocol rather than using static
   configuration of the external NVE is because the VN connectivity
   requirements can change frequently as VMs are brought up, moved, and
   brought down on various hypervisors throughout the data center or
   external cloud.

       +---------------+   Receive VN_connect;     +-------------------+
       |VN_Disconnected|   return Local_Tag value  |VN_Connected       |
       +---------------+   for VN if successful;   +-------------------+
       |VN_ID;         |-------------------------->|VN_ID;             |
       |VN_State=      |                           |VN_State=connected;|
       |disconnected;  |                           |Num_TSI_Associated;|
       |               |<--Receive VN_disconnect---|Local_Tag;         |
       +---------------+                           |VN_Context;        |

            Figure 5. State Transition Example of a VAP Instance
                         on an External NVE

   Figure 5 shows the state transition for a VAP on the external NVE. An
   NVE that supports the hypervisor to NVE control plane protocol should
   support one instance of the state machine for each active VN. The
   state transition on the external NVE is normally triggered by the
   hypervisor-facing side events and behaviors. Some of the interleaved
   interaction between NVE and NVA will be illustrated to better explain
   the whole procedure; while others of them may not be shown.

   The external NVE must be notified when an End Device requires
   connection to a particular VN and when it no longer requires
   connection. Connection clean up for the failed devices should be
   employed which is out of the scope of the protocol specified in this

   In addition, the external NVE should provide a local tag value for
   each connected VN to the End Device to use for exchanging packets
   between the End Device and the external NVE (e.g. a locally
   significant [IEEE 802.1Q] tag value). How "local" the significance is
   depends on whether the Hypervisor has a direct physical connection to
   the external NVE (in which case the significance is local to the
   physical link), or whether there is an Ethernet switch (e.g. a blade
   switch) connecting the Hypervisor to the NVE (in which case the
   significance is local to the intervening switch and all the links
   connected to it).

   These VLAN tags are used to differentiate between different VNs as
   packets cross the shared access network to the external NVE. When the
   external NVE receives packets, it uses the VLAN tag to identify their
   VN coming from a given TSI, strips the tag, adds the appropriate
   overlay encapsulation for that VN, and sends it towards the
   corresponding remote NVE across the underlying IP network.

   The Identification of the VN in this protocol could either be through
   a VN Name or a VN ID. A globally unique VN Name facilitates
   portability of a Tenant's Virtual Data Center. Once an external NVE
   receives a VN connect indication, the NVE needs a way to get a VN
   Context allocated (or receive the already allocated VN Context) for a
   given VN Name or ID (as well as any other information needed to
   transmit encapsulated packets).  How this is done is the subject of
   the NVE-to-NVA protocol which are part of work items 1 and 2 in
   [RFC7364]. The external NVE needs to synchronize the mapping
   information of the local tag and VN Name or VN ID with NVA.

   The VN_connect message can be explicit or implicit. Explicit means
   the hypervisor sends a request message explicitly for the connection
   to a VN. Implicit means the external NVE receives other messages,
   e.g. very first TSI associate message (see the next subsection) for a
   given VN, that implicitly indicate its interest in connecting to a

   A VN_disconnect message indicates that the NVE can release all the
   resources for that disconnected VN and transit to VN_disconnected
   state. The local tag assigned for that VN can possibly be reclaimed
   for use by another VN.

3.2 TSI Associate and Activate

   Typically, a TSI is assigned a single MAC address and all frames
   transmitted and received on that TSI use that single MAC address. As
   mentioned earlier, it is also possible for a Tenant System to
   exchange frames using multiple MAC addresses or packets with multiple
   IP addresses.

   Particularly in the case of a TS that is forwarding frames or packets
   from other TSs, the external NVE will need to communicate the mapping
   between the NVE's IP address on the underlying network and ALL the
   addresses the TS is forwarding on behalf of the corresponding VN to
   the NVA.

   The NVE has two ways it can discover the tenant addresses for which
   frames are to be forwarded to a given End Device (and ultimately to
   the TS within that End Device).

   1.  It can glean the addresses by inspecting the source addresses in
   packets it receives from the End Device.

   2.  The hypervisor can explicitly signal the address associations of
   a TSI to the external NVE. An address association includes all the
   MAC and/or IP addresses possibly used as source addresses in a packet
   sent from the hypervisor to external NVE. The external NVE may
   further use this information to filter the future traffic from the

   To use the second approach above, the "hypervisor-to-NVE" protocol
   must support End Devices communicating new tenant addresses
   associations for a given TSI within a given VN.

   Figure 6 shows the example of a state transition for a TSI connecting
   to a VAP on the external NVE. An NVE that supports the hypervisor to
   NVE control plane protocol may support one instance of the state
   machine for each TSI connecting to a given VN.

                 disassociate   +--------+     disassociate
               +--------------->|  Init  |<--------------------+
               |                +--------+                     |
               |                |        |                     |
               |                |        |                     |
               |                +--------+                     |
               |                  |    |                       |
               |       associate  |    |  activate             |
               |      +-----------+    +-----------+           |
               |      |                            |           |
               |      |                            |           |
               |     \|/                          \|/          |
       +--------------------+                  +---------------------+
       |     Associated     |                  |       Activated     |
       +--------------------+                  +---------------------+
       |TSI_ID;             |                  |TSI_ID;              |
       |Port;               |-----activate---->|Port;                |
       |VN_ID;              |                  |VN_ID;               |
       |State=associated;   |                  |State=activated ;    |-+
     +-|Num_Of_Addr;        |<---deactivate ---|Num_Of_Addr;         | |
     | |List_Of_Addr;       |                  |List_Of_Addr;        | |
     | +--------------------+                  +---------------------+ |
     |                    /|\                     /|\                  |
     |                     |                       |                   |
     +---------------------+                       +-------------------+
      add/remove/updt addr;                        add/remove/updt addr;
      or update port;                              or update port;

              Figure 6 State Transition Example of a TSI Instance
                             on an External NVE

   The Associated state of a TSI instance on an external NVE indicates
   all the addresses for that TSI have already associated with the VAP
   of the external NVE on a given port e.g. on port p for a given VN but
   no real traffic to and from the TSI is expected and allowed to pass
   through. An NVE has reserved all the necessary resources for that
   TSI. An external NVE may report the mappings of its underlay IP
   address and the associated TSI addresses to NVA and relevant network
   nodes may save such information to their mapping tables but not their
   forwarding tables. An NVE may create ACL or filter rules based on the
   associated TSI addresses on that attached port p but not enable them
   yet. The local tag for the VN corresponding to the TSI instance
   should be provisioned on port p to receive packets.

   The VM migration event (discussed section 2) may cause the hypervisor
   to send an associate message to the NVE connected to the destination
   hypervisor of the migration. A VM creation event may also cause to
   the same practice.

   The Activated state of a TSI instance on an external NVE indicates
   that all the addresses for that TSI are functioning correctly on a
   given port e.g. port p and traffic can be received from and sent to
   that TSI via the NVE. The mappings of the NVE's underlay IP address
   and the associated TSI addresses should be put into the forwarding
   table rather than the mapping table on relevant network nodes. ACL or
   filter rules based on the associated TSI addresses on the attached
   port p in the NVE are enabled. The local tag for the VN corresponding
   to the TSI instance must be provisioned on port p to receive packets.

   The Activate message makes the state transit from Init or Associated
   to Activated. VM creation, VM migration, and VM resumption events
   discussed in Section 4 may trigger sending the Activate message from
   the hypervisor to the external NVE.

   TSI information may get updated in either the Associated or Activated
   state. The following are considered updates to the TSI information:
   add or remove the associated addresses, update the current associated
   addresses (for example updating IP for a given MAC), and update the
   NVE port information based on where the NVE receives messages. Such
   updates do not change the state of TSI. When any address associated
   with a given TSI changes, the NVE should inform the NVA to update the
   mapping information for NVE's underlying address and the associated
   TSI addresses. The NVE should also change its local ACL or filter
   settings accordingly for the relevant addresses. Port information
   updates will cause the provisioning of the local tag for the VN
   corresponding to the TSI instance on new port and removal from the
   old port.

3.3 TSI Disassociate and Deactivate

   Disassociate and deactivate behaviors are conceptually the reverse of
   associate and activate.

   From Activated state to Associated state, the external NVE needs to
   make sure the resources are still reserved but the addresses
   associated to the TSI are not functioning. No traffic to or from the
   TSI is expected or allowed to pass through. For example, the NVE
   needs to tell the NVA to remove the relevant addresses mapping
   information from forwarding and routing tables. ACL and filtering
   rules regarding the relevant addresses should be disabled.

   From Associated or Activated state to the Init state, the NVE
   releases all the resources relevant to TSI instances. The NVE should
   also inform the NVA to remove the relevant entries from mapping
   table. ACL or filtering rules regarding the relevant addresses should
   be removed. Local tag provisioning on the connecting port on NVE
   should be cleared.

   A VM suspension event (discussed in section 2) may cause the relevant
   TSI instance(s) on the NVE to transit from Activated to Associated

   A VM pause event normally does not affect the state of the relevant
   TSI instance(s) on the NVE as the VM is expected to run again soon.

   A VM shutdown event will normally cause the relevant TSI instance(s)
   on the NVE to transition to Init state from Activated state. All
   resources should be released.

   A VM migration will cause the TSI instance on the source NVE to leave
   Activated state. When a VM migrates to another hypervisor connecting
   to the same NVE, i.e. source and destination NVE are the same, NVE
   should use TSI_ID and incoming port to differentiate two TSI

   Although the triggering messages for the state transition shown in
   Figure 6 does not indicate the difference between a VM
   creation/shutdown event and a VM migration arrival/departure event,
   the external NVE can make optimizations if it is given such
   information. For example, if the NVE knows the incoming activate
   message is caused by migration rather than VM creation, some
   mechanisms may be employed or triggered to make sure the dynamic
   configurations or provisionings on the destination NVE are the same
   as those on the source NVE for the migrated VM. For example an IGMP
   query [RFC2236] can be triggered by the destination external NVE to
   the migrated VM so that VM is forced to send an IGMP report to the
   multicast router. Then a multicast router can correctly route the
   multicast traffic to the new external NVE for those multicast groups
   the VM joined before the migration.

4. Hypervisor-to-NVE Control Plane Protocol Requirements

   Req-1: The protocol MUST support a bridged network connecting End
   Devices to the External NVE.

   Req-2: The protocol MUST support multiple End Devices sharing the
   same External NVE via the same physical port across a bridged

   Req-3: The protocol MAY support an End Device using multiple external
   NVEs simultaneously, but only one external NVE for each VN.

   Req-4: The protocol MAY support an End Device using multiple external
   NVEs simultaneously for the same VN.

   Req-5: The protocol MUST allow the End Device to initiate a request
   to its associated External NVE to be connected/disconnected to a
   given VN.

   Req-6: The protocol MUST allow an External NVE initiating a request
   to its connected End Devices to be disconnected from a given VN.

   Req-7: When a TS attaches to a VN, the protocol MUST allow for an End
   Device and its external NVE to negotiate one or more locally-
   significant tag(s) for carrying traffic associated with a specific VN
   (e.g., [IEEE 802.1Q] tags).

   Req-8: The protocol MUST allow an End Device initiating a request to
   associate/disassociate and/or activate/deactive some or all
   address(es) of a TSI instance to a VN on an NVE port.

   Req-9: The protocol MUST allow the External NVE initiating a request
   to disassociate and/or deactivate some or all address(es) of a TSI
   instance to a VN on an NVE port.

   Req-10: The protocol MUST allow an End Device initiating a request to
   add, remove or update address(es) associated with a TSI instance on
   the external NVE. Addresses can be expressed in different formats,
   for example, MAC, IP or pair of IP and MAC.

   Req-11: The protocol MUST allow the External NVE to authenticate and the connected
   End Device connected. to authenticate each other.

   Req-12: The protocol MUST be able to run over L2 links between the
   End Device and its External NVE.

   Req-13: The protocol SHOULD support the End Device indicating if an
   associate or activate request from it is the result of a VM hot
   migration event.

5. VDP Applicability and Enhancement Needs

   Virtual Station Interface (VSI) Discovery and Configuration Protocol
   (VDP) [IEEE 802.1Q] can be the control plane protocol running between
   the hypervisor and the external NVE. Appendix A illustrates VDP for
   the reader's information.

   VDP facilitates the automatic discovery and configuration of Edge
   Virtual Bridging (EVB) stations and Edge Virtual Bridging (EVB)
   bridges. An EVB station is normally an end station running multiple
   VMs. It is conceptually equivalent to a hypervisor in this document.
   An EVB bridge is conceptually equivalent to the external NVE.

   VDP is able to pre-associate/associate/de-associate a VSI on an EVB
   station with a port on the EVB bridge. A VSI is approximately the
   concept of a virtual port by which a VM connects to the hypervisor in
   this document's context. The EVB station and the EVB bridge can reach
   agreement on VLAN ID(s) assigned to a VSI via VDP message exchange.
   Other configuration parameters can be exchanged via VDP as well. VDP
   is carried over the Edge Control Protocol(ECP) [IEEE 802.1Q] which
   provides a reliable transportation over a layer 2 network.

   VDP protocol needs some extensions to fulfill the requirements listed
   in this document. Table 1 shows the needed extensions and/or
   clarifications in the NVO3 context.

   | Req  | Supported |   remarks                                     |
   |      | by VDP?   |                                               |
   | Req-1|           |                                               |
   +------+           |Needs extension. Must be able to send to a     |
   | Req-2|           |specific unicast MAC and should be able to send|
   +------+ Partially |to a non-reserved well known multicast address |
   | Req-3|           |other than the nearest customer bridge address.|
   +------+           |                                               |
   | Req-4|           |                                               |
   | Req-5| Yes       |VN is indicated by GroupID                     |
   | Req-6| Yes       |Bridge sends De-Associate                      |
   |      |           |VID==NULL in request and bridge returns the    |
   | Req-7| Yes       |assigned value in response or specify GroupID  |
   |      |           |in request and get VID assigned in returning   |
   |      |           |response. Multiple VLANs per group are allowed.|
   |      |           |  requirements          |  VDP equivalence     |
   |      |           +------------------------+----------------------+
   |      |           |  associate/disassociate|pre-asso/de-associate |
   | Req-8| Partially |  activate/deactivate   |associate/de-associate|
   |      |           +------------------------+----------------------|
   |      |           |Needs extension to allow associate->pre-assoc  |
   | Req-9| Yes       | VDP bridge initiates de-associate             |
   |Req-10| Partially |Needs extension for IPv4/IPv6 address. Add a   |
   |      |           |new "filter info format" type.                 |
   |Req-11| No        |Out-of-band mechanism is preferred, e.g. MACSec|
   |      |           |or 802.1X. Implicit authentication based on    |
   |      |           |control of physical connectivity exists in VDP |
   |      |           |when the External NVE connects to the End      |
   |      |           |Device directly and is reachable with the      |
   |      |           |nearest customer bridge address.               |
   |Req-12| Yes       |L2 protocol naturally                          |
   |      |           |M bit for migrated VM on destination hypervisor|
   |      |           |and S bit for that on source hypervisor.       |
   |Req-13| Partially |It is indistinguishable when M/S is 0 between  |
   |      |           |no guidance and events not caused by migration |
   |      |           |where NVE may act differently. Needs new       |
   |      |           |New bits for migration indication in new       |
   |      |           |"filter info format" type.                     |
                 Table 1 Compare VDP with the requirements

   Simply adding the ability to carry layer 3 addresses, VDP can serve
   the Hypervisor-to-NVE control plane functions pretty well. Other
   extensions are the improvement of the protocol capabilities for
   better fit in an NVO3 network.

6. Security Considerations

   External NVEs must ensure that only properly authorized Tenant
   Systems are allowed to join and become a part of any particular
   Virtual Network. In some cases, tNVE may want to connect to the
   authenticated nNVE
   for provisioning purpose. Then a mutual
   authentication between purposes. This may require that the tNVE tand
   authenticate the nNVE is required. in addition to the nNVE authenticating the
   tNVE. If a secure channel is required between tNVE and nNVE to carry
   encrypted split-
   NVE split-NVE control plane protocol payload, the protocol, then existing mechanisms like
   such as MACsec [IEEE 802.1AE] can be used. In some deployments,
   authentication may be implicit based on control of physical
   connectivity, e.g., if the nNVE is located in the bridge that is
   directly connected to the server that contains the tNVE. Use of
   "nearest customer bridge address" in VDP [IEEE 802.1Q] is an example
   where this sort of implicit authentication is possible, although
   explicit authentication also applies in that case.

   As the control plane protocol results in configuration changes for
   both the tNVE and nNVE, tNVE and nNVE implementations should log all
   state changes, including those described in Section 3.
   Implementations should also log significant protocol events, such as
   establishment or loss of control plane protocol connectivity between
   the tNVE and nNVE and authentication results.

   In addition, external NVEs will need appropriate mechanisms to ensure
   that any hypervisor wishing to use the services of an NVE is properly
   authorized to do so.  One design point is whether the hypervisor
   should supply the external NVE with necessary information (e.g., VM
   addresses, VN information, or other parameters) that the external NVE
   uses directly, or whether the hypervisor should only supply a VN ID
   and an identifier for the associated VM (e.g., its MAC address), with
   the external NVE using that information to obtain the information
   needed to validate the hypervisor-provided parameters or obtain
   related parameters in a secure manner. The former approach can be
   used in a trusted environment so that the external NVE can directly
   use all the information retrieved from the hypervisor for local
   configuration. It saves the effort on the external NVE side from
   information retrieval and/or validation. The latter approach gives
   more reliable information as the external NVE needs to retrieve them
   from some management system database. Especially some network related
   parameters like VLAN IDs can be passed back to hypervisor to be used
   as a more authoritative provisioning. However in certain cases, it is
   difficult or inefficient for an external NVE to have access or query
   on some information to those management systems. Then the external
   NVE has to obtain those information from hypervisor.

7. IANA Considerations

   No IANA action is required.

8. Acknowledgements

   This document was initiated based on the merger of the drafts draft-
   kreeger-nvo3-hypervisor-nve-cp, draft-gu-nvo3-tes-nve-mechanism, and
   draft-kompella-nvo3-server2nve. Thanks to all the co-authors and
   contributing members of those drafts.

   The authors would like to specially thank Lucy Yong and Jon Hudson
   for their generous help in improving this document.

8. References

8.1  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC7365] Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
              Rekhter, "Framework for DC Network Virtualization",
              October 2014.

   [RFC7666] Asai H., MacFaden M., Schoenwaelder J., Shima K., Tsou T.,
              "Management Information Base for Virtual Machines
              Controlled by a Hypervisor", October 2015.

   [RFC8014] Black, D., Hudson, J., Kreeger, L., Lasserre, M., Narten,
              T., "An Architecture for Data-Center Network
              Virtualization over Layer 3 (NVO3)", December 2016.

   [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119
              Key Words ", BCP 14, RFC 8174, May 2017.

   [IEEE 802.1Q] IEEE, "Media Access Control (MAC) Bridges and Virtual
              Bridged Local Area Networks", IEEE Std 802.1Q-2014,
              November 2014.

8.2  Informative References

   [RFC2236]  Fenner, W., "Internet Group Management Protocol, Version
              2", RFC 2236, November 1997.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122, July

   [RFC7364] Narten, T., Gray, E., Black, D., Fang, L., Kreeger, L., and
              M. Napierala, "Problem Statement: Overlays for Network
              Virtualization", October 2014.

   [IEEE 802.1AE] IEEE, "MAC Security (MACsec)", IEEE Std 802.1AE-2006,
              August 2006.

Appendix A. IEEE 802.1Q VDP Illustration (For information only)

   The VDP (VSI Discovery and Discovery and Configuration Protocol,
   clause 41 of [IEEE 802.1Q]) can be considered as a controlling
   protocol running between the hypervisor and the external bridge. VDP
   association TLV structure are formatted as shown in Figure A.1.

   |TLV type|TLV info|Status|VSI  |VSI Type|VSI ID|VSI ID|Filter|Filter|
   |        |string  |      |Type |Version |Format|      |Info  |Info  |
   |        |length  |      |ID   |        |      |      |format|      |
   |                 |      |<----VSI type&instance----->|<--Filter--->|
   |                 |      |<-------------VSI attributes------------->|
   |<--TLV header--->|<-----------TLV information string ------------->|

                          Figure A.1: VDP association TLV

   There are basically four TLV types.

   1. Pre-associate: Pre-associate is used to pre-associate a VSI
   instance with a bridge port.  The bridge validates the request and
   returns a failure Status in case of errors.  Successful pre-associate
   does not imply that the indicated VSI Type or provisioning will be
   applied to any traffic flowing through the VSI. The pre-associate
   enables faster response to an associate, by allowing the bridge to
   obtain the VSI Type prior to an association.

   2. Pre-associate with resource reservation: Pre-associate with
   Resource Reservation involves the same steps as Pre-associate, but on
   success it also reserves resources in the bridge to prepare for a
   subsequent Associate request.

   3. Associate: Associate creates and activates an association between
   a VSI instance and a bridge port. An bridge allocates any required
   bridge resources for the referenced VSI. The bridge activates the
   configuration for the VSI Type ID. This association is then applied
   to the traffic flow to/from the VSI instance.

   4. De-associate: The de-associate is used to remove an association
   between a VSI instance and a bridge port. Pre-associated and
   associated VSIs can be de-associated. De-associate releases any
   resources that were reserved as a result of prior associate or pre-
   Associate operations for that VSI instance.

   De-associate can be initiated by either side and the other types can
   only be initiated by the server side.

   Some important flag values in VDP Status field:

   1. M-bit (Bit 5): Indicates that the user of the VSI (e.g., the VM)
   is migrating (M-bit = 1) or provides no guidance on the migration of
   the user of the VSI (M-bit = 0).  The M-bit is used as an indicator
   relative to the VSI that the user is migrating to.

   2. S-bit (Bit 6): Indicates that the VSI user (e.g., the VM) is
   suspended (S-bit = 1) or provides no guidance as to whether the user
   of the VSI is suspended (S-bit = 0).  A keep-alive Associate request
   with S-bit = 1 can be sent when the VSI user is suspended. The S-bit
   is used as an indicator relative to the VSI that the user is
   migrating from.

   The filter information format currently defines 4 types. Each of the
   filter information is shown in details as follows.

   1. VID Filter Info format
      | #of     | PS   | PCP   | VID    |
      |entries  |(1bit)|(3bits)|(12bits)|
      |(2octets)|      |       |        |
                |<--Repeated per entry->|

         Figure A.2 VID Filter Info format

   2. MAC/VID Filter Info format
      | #of     |  MAC address | PS   | PCP   | VID    |
      |entries  |  (6 octets)  |(1bit)|(3bits)|(12bits)|
      |(2octets)|              |      |       |        |
                |<--------Repeated per entry---------->|

         Figure A.3 MAC/VID filter format

   3. GroupID/VID Filter Info format
      | #of     |  GroupID     | PS   | PCP   | VID    |
      |entries  |  (4 octets)  |(1bit)|(3bits)|(12bits)|
      |(2octets)|              |      |       |        |
                |<--------Repeated per entry---------->|

         Figure A.4 GroupID/VID filter format

   4. GroupID/MAC/VID Filter Info format
   | #of     | GroupID  | MAC address | PS   | PCP | VID    |
   |entries  |(4 octets)| (6 octets)  |(1bit)|(3b )|(12bits)|
   |(2octets)|          |             |      |     |        |
             |<-------------Repeated per entry------------->|
         Figure A.5 GroupID/MAC/VID filter format

   The null VID can be used in the VDP Request sent from the station to
   the external bridge. Use of the null VID indicates that the set of
   VID values associated with the VSI is expected to be supplied by the
   bridge. The set of VID values is returned to the station via the VDP
   Response. The returned VID value can be a locally significant value.
   When GroupID is used, it is equivalent to the VN ID in NVO3. GroupID
   will be provided by the station to the bridge. The bridge maps
   GroupID to a locally significant VLAN ID.

   The VSI ID in VDP association TLV that identify a VM can be one of
   the following format: IPV4 address, IPV6 address, MAC address, UUID
   [RFC4122], or locally defined.

Authors' Addresses

   Yizhou Li
   Huawei Technologies
   101 Software Avenue,
   Nanjing 210012

   Phone: +86-25-56625409
   EMail: liyizhou@huawei.com

   Donald Eastlake
   Huawei R&D USA
   155 Beaver Street
   Milford, MA 01757 USA

   Phone: +1-508-333-2270
   EMail: d3e3e3@gmail.com

   Lawrence Kreeger
   Arrcus, Inc
   Email: lkreeger@gmail.com

   Thomas Narten

   Email: narten@us.ibm.com

   David Black
   Dell EMC
   176 South Street,
   Hopkinton, MA 01748 USA

   Email: david.black@dell.com