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Versions: 00 draft-ietf-nvo3-hpvr2nve-cp-req

NVO3 Working Group                                             Yizhou Li
INTERNET-DRAFT                                                 Lucy Yong
Intended Status: Informational                       Huawei Technologies
                                                        Lawrence Kreeger
                                                                   Cisco
                                                           Thomas Narten
                                                                     IBM
                                                             David Black
                                                                     EMC
Expires: November 17, 2014                                  May 16, 2014


              Hypervisor to NVE Control Plane Requirements
                  draft-yizhou-nvo3-hpvr2nve-cp-req-00


Abstract

   This document describes the control plane protocol requirements when
   NVE is not co-located with the hypervisor on a server. A control
   plane protocol (or protocols) between a hypervisor and its associated
   external NVE(s) is used for the hypervisor to populate its virtual
   machines states to the NVE(s) for further handling. This document
   illustrates the functionalities required by such control plane
   signaling protocols and outlines the high level requirements to be
   fulfiled. Virtual machine states and state transitioning are
   summarized to help clarifying the needed 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
   Task Force (IETF), its areas, and its working groups.  Note that
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   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html




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   The list of Internet-Draft Shadow Directories can be accessed at
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Copyright and License Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2  Target Scenarios  . . . . . . . . . . . . . . . . . . . . .  4
   2. VM Lifecycle  . . . . . . . . . . . . . . . . . . . . . . . . .  6
     2.1 VM Creation  . . . . . . . . . . . . . . . . . . . . . . . .  6
     2.2 VM Live Migration  . . . . . . . . . . . . . . . . . . . . .  7
     2.3 VM termination . . . . . . . . . . . . . . . . . . . . . . .  7
     2.4 VM Pause, suspension and resumption  . . . . . . . . . . . .  8
   3. Hypervisor-to-NVE Signaling protocol functionality  . . . . . .  8
     3.1 VN connect and disconnect  . . . . . . . . . . . . . . . . .  8
     3.2 TSI associate and activate . . . . . . . . . . . . . . . . . 10
     3.3 TSI disassociate, deactivate and clear . . . . . . . . . . . 12
   4. Hypervisor-to-NVE Signaling Protocol requirements . . . . . . . 13
   5. Security Considerations . . . . . . . . . . . . . . . . . . . . 14
   6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 15
   7. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 15
   8. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     8.1  Normative References  . . . . . . . . . . . . . . . . . . . 15
     8.2  Informative References  . . . . . . . . . . . . . . . . . . 15
   Appendix A. IEEE 802.1Qbg VDP Illustration . . . . . . . . . . . . 16
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19







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1.  Introduction

   This document describes the control plane protocol requirements when
   NVE is not co-located with the hypervisor on a server. A control
   plane protocol (or protocols) between a hypervisor and its associated
   external NVE(s) is used for the hypervisor to populate its virtual
   machines states to the NVE(s) for further handling. This protocol is
   mentioned in NVO3 problem statement [I-D.ietf-nvo3-overlay-problem-
   statement] as the third work item. When TS and NVE are on the
   separate devices, we also call it split TS-NVE architecture and it is
   the primary interest in this document.

   Virtual machine states and state transitioning are summarized in this
   document to illustrates the functionalities required by the control
   plane signaling protocols between hypervisor and the external NVE.
   Then the high level requirements to be fulfiled are outlined.

   This document uses the term "hypervisor" throughout when describing
   the scenario where NVE functionality is implemented on a separate
   device from the "hypervisor" that contains a VM connected to a VN.
   In this context, the term "hypervisor" is meant to cover any device
   type where the NVE functionality is offloaded in this fashion, e.g.,
   a Network Service Appliance.

   This document often uses the term "VM" and "Tenant System" (TS)
   interchangeably, 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 may be another type of TS. When this
   document uses the term VM, it will in most cases apply to other types
   of TSs.

1.1  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

   This document uses the same terminology as found in [I-D.ietf-nvo3-
   framework] and [I-D.ietf-nvo3-nve-nva-cp-req]. This section defines
   additional terminology used by this document.

   VN Profile:  Meta data associated with a VN that is 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 could use the VN ID or VN Name to obtain the VN Profile.

   VSI: Virtual Station Interface. [IEEE 802.1Qbg]



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


1.2  Target Scenarios

   In split TS-NVE architecture, an external NVE can provide an offload
   of the encapsulation / decapsulation function, network policy
   enforcement, as well as the VN Overlay protocol overheads.  This
   offloading may provide performance improvements and/or resource
   savings to the End Device (e.g. hypervisor) making use of the
   external NVE.

   The following figures give example scenarios where the Tenant System
   and NVE are on different devices.

           Hypervisor             Access Switch
      +------------------+       +-----+-------+
      | +--+   +-------+ |       |     |       |
      | |VM|---|       | | VLAN  |     |       |
      | +--+   |Virtual|---------+ NVE |       +--- Underlying
      | +--+   |Switch | | Trunk |     |       |    Network
      | |VM|---|       | |       |     |       |
      | +--+   +-------+ |       |     |       |
      +------------------+       +-----+-------+
             Hypervisor with an External NVE



                                  Access
           Hypervisor             Switch         NVE
      +------------------+       +-----+       +-----+
      | +--+   +-------+ |       |     |       |     |
      | |VM|---|       | | VLAN  |     | VLAN  |     |
      | +--+   |Virtual|---------+     +-------+     +--- Underlying
      | +--+   |Switch | | Trunk |     | Trunk |     |    Network
      | |VM|---|       | |       |     |       |     |
      | +--+   +-------+ |       |     |       |     |
      +------------------+       +-----+       +-----+
       Hypervisor with an External NVE across an Ethernet Access Switch












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

                  Figure 1 Split TS-NVE Architecture

   Tenant Systems connect to NVEs via a Tenant System Interface (TSI).
   The TSI logically connects to the NVE via a Virtual Access Point
   (VAP) [I-D.ietf-nvo3-arch]. NVE may provide Layer 2 or Layer 3
   forwarding. In split TS-NVE architecture, external NVE may be able to
   reach multiple MAC and IP addresses via a TSI. For example, Tenant
   Systems that are providing network services (such as firewall, load
   balancer, VPN gateway) are likely to have complex address hierarchy.
   It implies if a given TSI disassociates from one VN, all the MAC and
   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.

   1.3 Motivations and Purpose

   The problem statement [I-D.ietf-nvo3-overlay-problem-statement],
   discusses the needs for a control plane protocol (or protocols) to
   populate each NVE with the state needed to perform its functions.

   In one common scenario, an NVE provides overlay
   encapsulation/decapsulation packet forwarding services to Tenant
   Systems (TSs) that are co-resident with 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 TS-NVE architecture scenarios, as shown in figure 1, some
   control plane signaling protocol needs to run between hypervisor and
   external NVE to pass the relevant state information. Such interaction
   is mandatory. This document will identify the requirements for such
   signaling protocol.




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


2. VM Lifecycle

   [I-D.ietf-opsawg-vmm-mib] shows the state transition of a VM in its
   figure 2. Some of the VM states are of the interest to the external
   NVE. This section illustrates the relevant phases or event in VM
   lifecycle. It should be noted 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 TS-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

   VM creation runs through the states in the order of preparing,
   shutdown and running [I-D.ietf-opsawg-vmm-mib]. The end device
   allocates and initializes local virtual resources like storage in the
   VM preparing state. In shutdown state, VM has everything ready except
   that CPU execution is not scheduled by the hypervisor and VM's memory
   is not resident in the hypervisor. From the shutdown state to running
   state, normally it requires the human execution or system triggered
   event. Running state indicates the VM is in the normal execution
   state. Frame can be sent and received correctly. No ongoing
   migration, suspension or shutdown is in process.

   In VM creation phase, tenant system 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 parameters or information have been provisioned properly.
   External NVE should be informed with VM's MAC address and/or IP
   address. Another example is that hypervisor may use a locally
   significant VLAN ID to indicate the traffic destined to a specified
   VN. Both hypervisor and NVE sides should agree on that VID value for
   later traffic identification and forwarding.

   External NVE needs to do some preparation work before it signals
   successful association with tenant system. Such preparation work may
   include locally saving the states and binding information of the
   tenant system and its VN, communicating with peer NVEs and/or NVA for
   network provisioning, etc.




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   Tenant System association should be performed before VM enters
   running state, preferably in shutdown state. If association with
   external NVE fails, VM should not go into running state.

2.2 VM Live Migration

   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, suspend/resume (or
   "cold") migration consists of suspending VM execution on one server
   and resuming it on another. For simplicity, the following abstract
   summary about live migration assumes shared storage, so that the VM's
   storage is accessible to the source and destination servers. Assume
   VM migrates from hypervisor 1 to hypervisor 2. VM live migration
   involves the state transition on both hypervisors, source hypervisor
   1 and destination hypervisor 2. VM state on source hypervisor 1
   transits from running to migrating and then to shutdown [I-D.ietf-
   opsawg-vmm-mib]. VM state on destination hypervisor 2 transits from
   shutdown to migrating and then running.

   External NVE connecting to destination hypervisor 2 has to associate
   the migrating VM with it by saving VM's MAC and/or IP addresses, its
   VN, locally significant VID if any, and provisioning other network
   related parameters of VM. The 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. VM on destination
   hypervisor 2 SHOULD not go to running state before all the network
   provisioning and binding has been done.

   VM on source hypervisor and destination hypervisor SHOULD not be in
   running state at the same time during migration. VM on source
   hypervisor goes into shutdown state only when VM on destination
   hypervisor has successfully been entering the running state. It is
   possible that VM on the source hypervisor stays in migrating state
   for a while after VM on the destination hypervisor is in running
   state.

2.3 VM termination

   VM termination is also referred to as "powering off" a VM. VM
   termination leads its state going to shutdown. There are two possible
   causes to terminate a VM [I-D.ietf-opsawg-vmm-mib], one is the normal
   "power off" of a running VM; the other is that VM has been migrated
   to other place and the VM image on the source hypervisor has to stop
   executing and to be shutdown.

   In VM termination, the external NVE connecting to that VM needs to



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   deprovision the VM, i.e. delete the network parameters associated
   with that VM. In other words, external NVE has to de-associate the
   VM.

2.4 VM Pause, suspension and resumption

   VM pause event leads VM transiting from running state to paused
   state. Paused state indicates VM is resident in memory but no longer
   scheduled to execute by the hypervisor [I-D.ietf-opsawg-vmm-mib]. VM
   can be easily re-activated from paused state to running state.

   VM suspension leads VM to transit state from running to suspended and
   VM resumption leads VM to transit state from suspended to running.
   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 [I-
   D.ietf-opsawg-vmm-mib].

   In split TS-NVE architecture, external NVE should keep any paused or
   suspended VM in association as VM can return to running state at any
   time.

3. Hypervisor-to-NVE Signaling protocol functionality

3.1 VN connect and disconnect

   When an NVE is external, a protocol is needed between the End Device
   (e.g. Hypervisor) making use of the external NVE and the external NVE
   in order to make the 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.


    +---------------+   Recv 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;|
    |               |<----Recv VN_disconnect----|Local_Tag;         |
    +---------------+                           |VN_Context;        |
                                                +-------------------+

       Figure 2 State machine of a VAP instance on an external NVE



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   Figure 2 show the state machine for a VAP on the external NVE. An NVE
   that supports the hypervisor to NVE signaling 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 for better
   understanding of the whole procedures; while some of them may not be
   shown. More detailed information regarding that is available in [I-
   D.ietf-nvo3-nve-nva-cp-req].

   The NVE must be notified when an End Device requires connection to a
   particular VN and when it no longer requires connection. In addition,
   the external NVE must provide a local tag value for each connected VN
   to the End Device to use for exchange of packets between the End
   Device and the NVE (e.g. a locally significant 802.1Q tag value). How
   "local" the significance is depends on whether the Hypervisor has a
   direct physical connection to the 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
   NVE receives packets, it uses the VLAN tag to identify the VN of
   packets coming from a given TSI, strips the tag, and adds the
   appropriate overlay encapsulation for that VN and send to the
   corresponding VAP.

   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 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 (called NVE-to-NVA in this document) protocol which are part
   of work items 1 and 2 in [I-D.ietf-nvo3-overlay-problem-statement].

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


   A VN_disconnect message will make NVE release all the resources for
   that disconnected VN and transit to VN_disconnected state. The local



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   tag assigned for that VN can possibly be reclaimed by other 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 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 to NVA in each
   corresponding VN.

   The NVE has two ways in which it can discover the tenant addresses
   for which frames must 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. The 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. External NVE may further
   use this information to filter the future traffic from the
   hypervisor.

   To perform the second approach above, the "hypervisor-to-NVE"
   protocol requires a means to allow End Devices to communicate new
   tenant addresses associations for a given TSI within a given VN.

   Figure 3 shows the state machine for a TSI connecting to a VAP on the
   external NVE. An NVE that supports the hypervisor to NVE signaling
   protocol should support one instance of the state machine for each
   TSI connecting to a given VN.













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                disassociate;  +--------+
              +--------------->|  Init  |<--------clear-------+
              |or keepalive    +--------+                     |
              |timer timeout;  |        |                     |
              |                |        |                     |
              |                +--------+                     |
              |                  |    |                       |
              |       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;       |  or keepactive    List_Of_Addr;        | |
    | |ResetKeepaliveTimer;|  timer timeout;  |ResetKeepactiveTimer;| |
    | +--------------------+                  +---------------------+ |
    |                    /|\                     /|\                  |
    |                     |                       |                   |
    +---------------------+                       +-------------------+
     add/remove/updt addr;                        add/remove/updt addr;
     or update port; or                           or update port; or
     Recv keepalive pkt                           Recv keepactive pkt
     from TSI;                                    or data msg from TSI;

       Figure 3 State machine of a TSI instance on an external NVE

   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 port p for a given VN but no real traffic to and
   from the TSI is expected and allowed to pass through. NVE has
   reserved all the necessary resources for that TSI. NVE may report the
   mappings of NVE's underlay IP address and the associated TSI
   addresses to NVA and relevant network nodes may save such information
   to its mapping table but not forwarding table. NVE may create ACL or
   filter rules based on the associated TSI addresses on the attached
   port p but not enable them yet. Local tag for the VN corresponding to
   the TSI instance should be provisioned on port p to receive packets.

   VM migration discussed section 2 may cause the hypervisor send
   associate message to the NVE connecting the destination hypervisor
   the VM migrates to. It is similar as the resource reservation request



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   to make sure the VM can be successfully migrated later. If such
   association fails, VM may choose another destination hypervisor to
   migrate to or alert with an administrative message. VM creation event
   may also lead to the same practice.

   Activated state of a TSI instance on an external NVE indicates that
   all the addresses for that TSI functioning correctly on port p and
   traffic can be received from and sent to that TSI on NVE. The
   mappings of 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 NVE are
   enabled. Local tag for the VN corresponding to the TSI instance MUST
   be provisioned on port p to receive packets.

   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 activate message to be sent from
   the hypervisor to the external NVE.

   As mentioned in last subsection, associate or activate message from
   the very first TSI connecting to a VN on an NVE is also considered as
   the implicit VN_connect signal to create a VAP for that VN.

   TSI information may get updated either in Associated or Activated
   state. Add or remove the associated addresses, update current
   associated addresses for example updating IP for a given MAC, update
   NVE port information from which the message receives are all
   considered as TSI information updating. Such update does not change
   the state of TSI. When any address associated to a given TSI changes,
   NVE should inform the NVA to update the mapping information on NVE's
   underlying address and the associated TSI addresses. NVE should also
   change its local ACL or filter settings accordingly for the relevant
   addresses. Port information update will cause the local tag for the
   VN corresponding to the TSI instance provisioned on new port p and
   removed from old port.

   NVE keeps a timer for each TSI instance associated or activated on
   it. When NVE receives the keepalive or keepactive message for a TSI
   instance, it should reset the timer. Keepactive timer may also be
   reset by receiving the data packet from any associated address of the
   corresponding TSI instance. Keepactive timer times out leads the
   state transiting from Activated to Associated. Keepalive timer times
   out leads the state transiting from Associated to Init.

3.3 TSI disassociate, deactivate and clear

   Disassociate and deactivate conceptually are the reverse behaviors of



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   associate and activate. From Activated state to Associated state, NVE
   needs to make sure the resources still reserved but the addresses
   associated to the TSI not functioning and no traffic to and from the
   TSI expected and allowed to pass through. For example, NVE needs to
   inform NVA to remove the relevant addresses mapping information from
   forwarding or routing table. ACL or filtering rules regarding the
   relevant addresses should be disabled. From Associated or Activated
   state to Init state, NVE will release all the resource relevant to
   TSI instances. 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.

   VM suspension discussed in section 2 may cause the relevant TSI
   instance(s) on NVE transit from Activated to Associated state. VM
   pause normally does not affect the state of the relevant TSI
   instance(s) on NVE as the VM is expected to run again soon. VM
   shutdown will cause the relevant TSI instance(s) on NVE transit to
   Init state from Activated state. All resources should be released.

   VM migration will lead the TSI instance on the source NVE to leave
   Activated state. Such state transition on source NVE should not occur
   earlier than the TSI instance on the destination NVE transits to
   Activated state. Otherwise traffic interruption may occur. 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 instance.

   Although the triggering messages for state transition shown in Figure
   3 does not indicate the difference between VM creation/shutdown and
   VM migration arrival/departure, the NVE can make optimizations if it
   is notified of such information. For example, if NVE knows the
   incoming activate message 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
   same as those on the source NVE for the migrated VM, for example
   multicast group memberships.

4. Hypervisor-to-NVE Signaling Protocol requirements

   Req-1: The protocol is able to run between the hypervisor and its
   associated external NVE which may directly connected or bridged in
   split-NVE architecture.

   Req-2: The protocol MUST support the hypervisor initiating a request
   to its associated external NVE to be connected to a given VN.

   Req-3: In response to the connection request to a given VN received



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   on NVE's port p as per Req-1, the protocol SHOULD support NVE
   replying a locally significant tag assigned, for example 802.1Q tag
   value, to each of the VN it is member of. NVE should keep the record
   of VN ID, local tag assigned and port p triplet.

   Req-4: The protocol MUST support the hypervisor initiating a request
   to associate/disassociate, activate/deactive or clear a TSI instance
   to a VN on an NVE port. All requests should be logically consistent
   with text in section 5.2 & 5.3.

   Req-5: The protocol MUST support the hypervisor initiating a request
   to add, remove or update addresses associated with a TSI instance
   which has associated or activated on the external NVE. Addresses can
   be expressed in different formats, for example, MAC, IP or pair of IP
   and MAC.

   Req-6: When any request of the protocol fails, a reason code MUST be
   provided in the reply.

   Req-7: The protocol MAY support the hypervisor explicitly informing
   NVE when a migration starts. It may help NVE to differentiate a new
   associated/activated TSI resulting from VM creation or VM migration.

   Req-8: The protocol SHOULD be extensible to carry more parameters to
   meet future requirements, for example, QoS settings.

   There are multiple candidate protocols probably with some simple
   extensions that can be used to exchange signaling information between
   hypervisor and external NVE. They include VDP [IEEE 802.1Qbg], LLDP,
   XMPP, and HTTP REST. Multiple factors influence the choice of
   protocol(s), for example, connection between hypervisor and external
   NVE is L2 or L3. Appendix A illustrates VDP for reader's information.


5. Security Considerations

   NVEs must ensure that only properly authorized Tenant Systems are
   allowed to join and become a part of any specific Virtual Network. In
   addition, NVEs will need appropriate mechanisms to ensure that any
   hypervisor wishing to use the services of an NVE are properly
   authorized to do so. One design point is whether the hypervisor
   should supply the NVE with necessary information (e.g., VM addresses,
   VN information, or other parameters) that the 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 NVE using
   that information to obtain the information needed to validate the
   hypervisor-provided parameters or obtain related parameters in a
   secure manner.



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6. IANA Considerations

   No IANA action is required. RFC Editor: please delete this section
   before publication.

7. Acknowledgements

   This document was initiated and merged from 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.

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.


8.2  Informative References


   [I-D.ietf-nvo3-overlay-problem-statement] Narten, T., Gray, E.,
              Black, D., Fang, L., Kreeger, L., and M. Napierala,
              "Problem Statement: Overlays for Network Virtualization",
              draft-ietf-nvo3-overlay-problem-statement-04 (work in
              progress), July 2013.

   [I-D.ietf-nvo3-framework] Lasserre, M., Balus, F., Morin, T., Bitar,
              N., and Y. Rekhter, "Framework for DC Network
              Virtualization", draft-ietf-nvo3-framework-05 (work in
              progress), January 2014.

   [I-D.ietf-nvo3-nve-nva-cp-req] Kreeger, L., Dutt, D., Narten, T., and
              D. Black, "Network Virtualization NVE to NVA Control
              Protocol Requirements", draft-ietf-nvo3-nve-nva-cp-req-01
              (work in progress), October 2013.

   [I-D.ietf-nvo3-arch] Black, D., Narten, T., et al, "An Architecture
              for Overlay Networks (NVO3)", draft-narten-nvo3-arch, work
              in progress.

   [I-D.ietf-opsawg-vmm-mib] Asai H., MacFaden M., Schoenwaelder J.,
              Shima K., Tsou T., "Management Information Base for
              Virtual Machines Controlled by a Hypervisor", draft-ietf-
              opsawg-vmm-mib-00 (work in progress), February 2014.




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   [IEEE 802.1Qbg] IEEE, "Media Access Control (MAC) Bridges and Virtual
              Bridged Local Area Networks - Amendment 21: Edge Virtual
              Bridging", IEEE Std 802.1Qbg, 2012

   [8021Q] IEEE, "Media Access Control (MAC) Bridges and Virtual Bridged
              Local Area Networks", IEEE Std 802.1Q-2011, August, 2011



Appendix A. IEEE 802.1Qbg VDP Illustration

VDP has the format shown in Figure A.1. Virtual Station Interface (VSI)
is an interface to a virtual station that is attached to a downlink port
of an internal bridging function in server. VSI's VDP packet will be
handled by an external bridge. VDP is the controlling protocol running
between the hypervisor and the external bridge.


+--------+--------+------+----+----+------+------+------+-----------+
|TLV type|TLV info|Status|VSI |VSI |VSIID | VSIID|Filter|Filter Info|
| 7b     |str len |      |Type|Type|Format|      | Info |           |
|        |  9b    | 1oct |ID  |Ver |      |      |format|           |
|        |        |      |3oct|1oct| 1oct |16oct |1oct  | M oct     |
+--------+--------+------+----+----+------+------+------+-----------+
|                 |      |                       |                  |
|                 |      |<--VSI type&instance-->|<----Filter------>|
|                 |      |<------------VSI attributes-------------->|
|<--TLV header--->|<-------TLV info string = 23 + M octets--------->|

                       Figure A.1: VDP TLV definitions

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-association 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 successful
pre-association also reserves resources in the Bridge to prepare for a
subsequent Associate request.

3. Associate: The Associate creates and activates an association between
a VSI instance and a bridge port. The Bridge allocates any required



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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. Deassociate: 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.

Deassociate can be initiated by either side and the rest types of
messages 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 supports 4 types as the
following.

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

      Figure A.2 VID Filter Info format












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2. MAC/VID filter 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 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 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 hypervisor 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 Bridge can obtain VID values from the VSI Type whose identity is
specified by the VSI Type information in the VDP Request. 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
hypervisor to the bridge. The bridge will map GroupID to a locally
significant VLAN ID.


The VSIID in VDP request that identify a VM can be one of the following
format: IPV4 address, IPV6 address, MAC address, UUID or locally
defined.

We compare VDP against the requirements in the following Figure A.6. It
should be noted that the comparison is conceptual. Detail parameters
checking is not performed.



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 +------+-----------+----------------------------------------------+
 | Req  | VDP       |   remarks                                    |
 |      | supported?|                                              |
 +------+-----------+----------------------------------------------+
 | Req-1| partial   |support directly connected but not bridged    |
 +------+-----------+----------------------------------------------+
 | Req-2| Yes       |VN is represented by GroupID                  |
 +------+-----------+----------------------------------------------+
 | Req-3| Yes       |VID=NULL in request and bridge returns the    |
 |      |           |assigned value in response                    |
 +------+-----------+------------------------+---------------------+
 |      |           |  requiments            |  VDP equivalence    |
 |      |           +------------------------+---------------------+
 | Req-4| partial   |  associate/disassociate|  pre-asso/de-asso   |
 |      |           |  activate/deactivate   |  associate/nil      |
 |      |           |      clear             |   de-associate      |
 +------+-----------+------------------------+---------------------+
 | Req-5| partial   | VDP can handle MAC addresses properly. For IP|
 |      |           | addresses, it is not clearly specified.      |
 +------+-----------+----------------------------------------------+
 |      |           |                                              |
 | Req-6|  Yes      | Error type indicated in Status in response   |
 +------+-----------+----------------------------------------------+
 | Req-7|  Yes      | M bit indicated in Status in request         |
 +------+-----------+----------------------------------------------+
 |      |           | For certain information,e.g. new filter info |
 | Req-8|  partial  | format, VDP can easily be extended. For some,|
 |      |           | extensibility may be limited.                |
 +------+-----------+----------------------------------------------+

              Figure A.6   Compare VDP with the requirements

Authors' Addresses


   Yizhou Li
   Huawei Technologies
   101 Software Avenue,
   Nanjing 210012
   China

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

   Lucy Yong
   Huawei Technologies, USA

   Email: lucy.yong@huawei.com



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   Lawrence Kreeger
   Cisco

   Email: kreeger@cisco.com


   Thomas Narten
   IBM

   Email: narten@us.ibm.com
   David Black
   EMC

   Email: david.black@emc.com





































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