Dear all, A few comments on an otherwise excellent draft:
2. Introduction =============== You might want to differentiate between cold VM mobility - VM is stopped or paused, moved to another hypervisor/cluster/DC and restarted/resumed - where IP address preservation is desired or required, and hot VM mobility, where a running VM is moved to another location (hypervisor/cluster/DC). Fundamental differences between the two are: * Convergence time requirements - obviously highly relevant to hot VM mobility but not for the cold case; * ARP cache expiration - after a cold VM move, the hypervisor can bounce the VM virtual LAN interface (the TCP sessions are gone anyway) hopefully clearing the ARP cache. You might also want to mention storage-related issues (the moved VM has to have access to the same virtual disk), obviously in the "out-of-scope" part of the introduction. 2.1 Terminology =============== You might want to make the ToR definition more precise in case of port/fabric extenders. Reference to "controlling bridge" from EVB and 802.1BR would probably make most sense. Also, when defining L2 CUG, it would make sense to specify whether a VM participating in multiple L2 CUGs has multiple (logical) interfaces (one per L2 CUG), requiring simple VPNs, or one interface in multiple L2 CUGs, requiring overlapping VPNs. The rest of the text implies a VLAN-per-CUG approach, which translates into logical interface per L2 CUG, but it might be worth spelling out. 3.1 VLAN IDs ============ I would assume that most people familiar with network virtualization come to an immediate conclusion that you either need multiple (non-tagged) interfaces per VM or a VLAN-tagged VM interface, but these conclusions might be worth documenting. 3.4 Optimal IP routing ====================== There might be cases where the only L3-7 networking device between a VM and the outside world is a router (in which case the optimal IP routing is the biggest problem you have), but in most cases the headaches are caused by stateful devices in the path (load balancers, address translators and/or firewalls). Solving optimal IP routing is "easy" (at least we have demonstrable solutions), network device state transfer and session preservation on hot VM move is a much harder problem (with the exception of a hypervisor-based firewall). It would make sense to either expand the problem statement to include stateful devices, or make them explicitly out-of-scope. Kind regards, Ivan > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of > Yakov Rekhter > Sent: Monday, August 20, 2012 9:49 PM > To: [email protected] > Subject: [nvo3] draft-rekhter-nvo3-vm-mobility-issues-00.txt > > fyi, and comments... > ------- Forwarded Message > > Date: Mon, 20 Aug 2012 12:44:08 -0700 > From: [email protected] > To: [email protected] > Subject: I-D Action: draft-rekhter-nvo3-vm-mobility-issues-00.txt > > > A New Internet-Draft is available from the on-line Internet-Drafts > directories. > > > Title : Network-related VM Mobility Issues > Author(s) : Yakov Rekhter > Wim Henderickx > Ravi Shekhar > Luyuan Fang > Linda Dunbar > Ali Sajassi > Filename : draft-rekhter-nvo3-vm-mobility-issues-00.txt > Pages : 10 > Date : 2012-08-20 > > Abstract: > This document describes a set of network-related issues presented by > the desire to support seamless Virtual Machine mobility in the data > center and between data centers. In particular, it looks at the > implications of meeting the requirements for "seamless mobility". > > > The IETF datatracker status page for this draft is: > https://datatracker.ietf.org/doc/draft-rekhter-nvo3-vm-mobility-issues > > There's also a htmlized version available at: > http://tools.ietf.org/html/draft-rekhter-nvo3-vm-mobility-issues-00 > > > Internet-Drafts are also available by anonymous FTP at: > ftp://ftp.ietf.org/internet-drafts/ > > _______________________________________________ > I-D-Announce mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/i-d-announce > Internet-Draft directories: http://www.ietf.org/shadow.html or > ftp://ftp.ietf.org/ietf/1shadow-sites.txt > > ------- End of Forwarded Message > > _______________________________________________ > nvo3 mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/nvo3 _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
