--- 1/draft-ietf-nvo3-vmm-10.txt 2020-03-30 16:13:47.689468478 -0700 +++ 2/draft-ietf-nvo3-vmm-11.txt 2020-03-30 16:13:47.725469374 -0700 @@ -1,24 +1,24 @@ Network Working Group L. Dunbar Internet Draft Futurewei Intended status: Informational B. Sarikaya -Expires: September 27, 2020 Denpel Informatique +Expires: September 30, 2020 Denpel Informatique B.Khasnabish Independent T. Herbert Intel S. Dikshit Aruba-HPE - March 27, 2020 + March 30, 2020 Virtual Machine Mobility Solutions for L2 and L3 Overlay Networks - draft-ietf-nvo3-vmm-10 + draft-ietf-nvo3-vmm-11 Abstract This document describes virtual machine mobility solutions commonly used in data centers built with overlay-based network. This document is intended for describing the solutions and the impact of moving VMs (or applications) from one Rack to another connected by the Overlay networks. For layer 2, it is based on using an NVA (Network Virtualization @@ -47,21 +47,21 @@ months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html - This Internet-Draft will expire on September 26, 2020. + This Internet-Draft will expire on September 27, 2020. Copyright Notice Copyright (c) 2020 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 Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -75,31 +75,31 @@ 1. Introduction...................................................3 2. Conventions used in this document..............................4 3. Requirements...................................................5 4. Overview of the VM Mobility Solutions..........................6 4.1. Inter-VNs communication...................................6 4.2. VM Migration in Layer 2 Network...........................6 4.3. VM Migration in Layer-3 Network...........................8 4.4. Address and Connection Management in VM Migration.........9 5. Handling Packets in Flight....................................10 - 6. Moving Local State of VM......................................10 + 6. Moving Local State of VM......................................11 7. Handling of Hot, Warm and Cold VM Mobility....................11 - 8. Other Options.................................................11 - 9. VM Lifecycle Management.......................................12 - 10. Security Considerations......................................12 + 8. Other Options.................................................12 + 9. VM Lifecycle Management.......................................13 + 10. Security Considerations......................................13 11. IANA Considerations..........................................13 - 12. Acknowledgments..............................................13 - 13. Change Log...................................................13 - 14. References...................................................13 + 12. Acknowledgments..............................................14 + 13. Change Log...................................................14 + 14. References...................................................14 14.1. Normative References....................................14 - 14.2. Informative References..................................15 + 14.2. Informative References..................................16 1. Introduction This document describes the overlay-based data center networks solutions in supporting multitenancy and VM (Virtual Machine) mobility. Being able to move VMs dynamically, from one server to another, makes it possible for dynamic load balancing or work distribution. Therefore, dynamic VM Mobility is highly desirable for large scale multi-tenant DCs. This document is strictly within the DCVPN, as defined by the NVO3 Framework [RFC 7365]. The intent is to describe Layer 2 and Layer @@ -219,20 +219,27 @@ Inter VNs (Virtual Networks) communication refers to communication among tenants (or hosts) belonging to different VNs. Those tenants can be attached to the NVEs co-located in the same Data Center or in different Data centers. This document assumes that the inter- VNs communication is via the NVO3 Gateway as described in RFC8014 (NVO3 Architecture). RFC 8014 (Section 5.3) describes the NVO3 Gateway function which is to relay traffic onto and off of a virtual network, i.e. among different VNs. + When a VM communicates with an external entity, the VM is + effectively communicating with a peer in a different network or a + globally reachable host. Communicating with hosts in other VNs + and external hosts are all through the NVO3 Gateway. There are + different policies on the NVo3 Gateway to govern the communication + among VNs and with external hosts. + After a VM is moved to a new NVE, the VM's corresponding Gateway may need to change as well. If such a change is not possible, then the path to the external entity need to be hair-pinned to the NVO3 Gateway used prior to the VM move. 4.2. VM Migration in Layer 2 Network In a Layer-2 based approach, VM moving to another NVE does not change its IP address. But this VM is now under a new NVE, previously communicating NVEs may continue sending their packets @@ -442,95 +448,120 @@ restarted. In this document, all VM mobility is initiated by VM Management System. The Cold VM mobility only exchange the needed states between the Old NVE and the New NVE after the VM attached to the Old NVE is completely shut down. There is time delay before the new VM is launched. The cold mobility option can be used for non- critical applications and services that can tolerate interrupted TCP connections. - The Warm VM mobility refers to having the backup entities receive - backup information at more frequent intervals, so that it can take - less time to launch the VM under the new NVE and other NVEs that - communicate with the VM can be notified prior to the VM move. The - duration of the interval determines the effectiveness (or benefit) - of Warm VM mobility. The larger the duration, the less effective - the Warm VM mobility option becomes. + The Warm VM mobility refers to having the functional components + under the new NVE to receive running status of the VM at frequent + intervals, so that it can take less time to launch the VM under + the new NVE and other NVEs that communicate with the VM can be + notified of the VM move more promptly. The duration of the + interval determines the effectiveness (or benefit) of Warm VM + mobility. The larger the duration, the less effective the Warm VM + mobility option becomes. For Hot VM Mobility, once a VM moves to a New NVE, the VM IP address does not change and the VM should be able to continue to receive packets to its address(es). The VM needs to send a gratuitous Address Resolution message or unsolicited Neighbor Advertisement message upstream after each move. Upon starting at the New NVE, the VM should send an ARP or Neighbor Discovery message. Cold VM mobility also allows the Old NVE and all communicating NVEs to time out ARP/neighbor cache entries of the VM. It is necessary for the NVA to push the updated ARP/neighbor cache entry to NVEs or for NVEs to pull the updated ARP/neighbor cache entry from NVA. 8. Other Options VM Hot mobility is to enable uninterrupted running of the application or workload instantiated on the VM when the VM running conditions changes, such as utilization overload, hardware running - condition changes, or others. + condition changes, or others. Hot, Warm and Cold mobility are + planned activities which are managed by VM management system. - There is also a Hot Standby option to prevent unexpected failure - conditions, where there are VMs in both primary and secondary - NVEs. They have identical information and can provide services - simultaneously as in load-share mode of operation. If the VM in - the primary NVE fails, there is no need to actively move the VM to - the secondary NVE because the VM in the secondary NVE already - contain identical information. The Hot Standby option is the - costliest mechanism, and hence this option is utilized only for - mission-critical applications and services. In Hot Standby - option, regarding TCP connections, one option is to start with and - maintain TCP connections to two different VMs at the same time. - The least loaded VM responds first and pickup providing service - while the sender (origin) still continues to receive Ack from the - heavily loaded (secondary) VM and chooses not to use the service - of the secondary responding VM. If the situation (loading - condition of the primary responding VM) changes the secondary - responding VM may start providing service to the sender (origin). + For unexpected events, such as unexpected failure, a VM might need + to move to a new NVE, which is called Hot VM Failover in this + document. For Hot VM Failover, there are VMs in both primary and + secondary NVEs. They can provide services simultaneously as in + load-share mode of operation. If the VM in the primary NVE fails, + there is no need to actively move the VM to the secondary NVE + because the VM in the secondary NVE can immediately pick up the + processing. It is out of the scope of this document on how and + what information are exchange between the two VMs under two + different NVE. + + The VM Failover to the new NVE is transparent to the peers that + communicate with this VM. This can be achieved by both active VM + and standby VM share the same TCP port and same IP address. There + must be a load balancer that can distribute the packets to the VM + under the new NVE. The new VM can pick up providing service while + the sender (peer) still continues to receive Ack from the old VM + and chooses not to use the service of the secondary responding VM. + If the situation (loading condition of the primary responding VM) + changes the secondary responding VM may start providing service to + the sender (peers). + + If TCP states are not properly synchronized among the two VMs, the + VM under the New NVE after failover can force the peers to re- + establish a new TCP connection by stopping the previous TCP + connection. As most TCP connections are short lived, re- + establishing a new one is not a big problem. + + The Hot VM Failover option is the costliest mechanism, and hence + this option is utilized only for mission-critical applications and + services. 9. VM Lifecycle Management The VM lifecycle management is a complicated task, which is beyond the scope of this document. Not only it involves monitoring server utilization, balanced distribution of workload, etc., but also needs to manage seamlessly VM migration from one server to another. 10. Security Considerations Security threats for the data and control plane for overlay networks are discussed in [RFC8014]. ARP (IPv40 and ND (IPv6) are not secure, especially if we accept gratuitous versions in multi- tenant environment. - In Layer-3 based overlay data center networks, the problem of - address spoofing may arise. An NVE may have untrusted VMs - attached. This usually happens in cases like the VMs running third - party applications. Those untrusted VMs can send falsified ARP - (IPv4) and ND (IPv6) messages, causing NVE, NVO3 Gateway, and NVA - to be overwhelmed and not able to perform legitimate functions. - The attacker can intercept, modify, or even stop data in-transit - ARP/ND messages intended for other VNs and initiate DDOS attacks - to other VMs attached to the same NVE. + In Layer-3 based overlay data center networks, ARP and ND messages + can be used to mount address spoofing attacks. An NVE may have + untrusted VMs attached. This usually happens in cases like the VMs + running third party applications. Those untrusted VMs can send + falsified ARP (IPv4) and ND (IPv6) messages, causing NVE, NVO3 + Gateway, and NVA to be overwhelmed and not able to perform + legitimate functions. The attacker can intercept, modify, or even + stop data in-transit ARP/ND messages intended for other VNs and + initiate DDOS attacks to other VMs attached to the same NVE. A + simple black-hole attacks can be mounted by sending a falsified + ARP/ND message to indicate that the victim's IP address has moved + to the attacker's VM. That technique can also be used to mount + man-in-the-middle attacks with some more effort to ensure that the + intercepted traffic is eventually delivered to the victim. The locator-identifier mechanism given as an example (ILA) doesn't include secure binding. It doesn't discuss how to securely bind the new locator to the identifier. - This requires VM management system to apply stronger security - mechanisms when add a VM to an NVE. VM Management system is out of - scope of this document. + Because of those threats, VM management system needs to apply + stronger security mechanisms when add a VM to an NVE. Some tenants + may have requirement that prohibit their VMs to be co-attached to + the NVEs with other tenants. Some Data Centers have their NVO3 + Gateways to be equipped with capability to mitigate ARP/ND + threats, such as periodically exchanging its ARP/ND cache with + NVA's central control system. 11. IANA Considerations This document makes no request to IANA. 12. Acknowledgments The authors are grateful to Bob Briscoe, David Black, Dave R. Worley, Qiang Zu, Andrew Malis for helpful comments.