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Re: Misconceptions, was: IPv6 RA vs DHCPv6 - The chosen one?
From: Ray Soucy <rps () maine edu>
Date: Fri, 30 Dec 2011 13:39:38 -0500

VRRP is still useful, and for those who find it useful it has been
extended to IPv6 [RFC5798].  Vendors, such as Cisco, have already
begun shipping functional implementations as well it would seem.

There are certainly pieces of IPv6 that will need refinement (and we
will likely see that happen over time, after it is dominant).
Mobility and IPsec, for example, were touted as big benefits of IPv6,
but they didn't end up being that important (or useful) in their
current state.  The ability to have multiple prefixes from different
routers, and a failover mechanism was really a pre-NAT and pre-VRRP
idea.  It's not the common deployment that it was envisioned to be,
and our expectations of how fast these things happen has become a lot
higher.  Still, minor extensions could be made to these standard to
achieve a lot of the desired behavior, so I haven't given up on it all

It's hard to predict the future, and it's been over a decade since the
design for IPv6 was solidified and began to be implemented.

Let's not forget that what we call "Ethernet" today is very different
from Bob Metcalfe's Ethernet.

On Fri, Dec 30, 2011 at 11:47 AM, Kevin Loch <kloch () kl net> wrote:
Steven Bellovin wrote:

VRRP?  The Router Discovery Protocol (RFC 1256).  But given
how much more reliable routers are today than in 1984, I'm
not convinced it's that necessary these days.

VRRP is an absolutely essential protocol in today's Internet.  We use
it on every non-bgp customer port.  Routers still have routing and
performance issues, hardware failures and routine software upgrades.
The layer2 infrastructure between the routers and the customer is also
susceptible to various hardware/software/maintenance problems and fiber
cuts and VRRP can help work around some of those.  A nice side benefit
is the virtual mac addresses that allow for migration to new routers
without the mac address of the default gateway changing.

One key advantage of VRRP over RA's is that you can have multiple
instances on the same layer2 network (vlan) with different functions.

It is very common to have different "routers" (routers, firewalls or
load balancers) on the same vlan with different functions in hosting
environments.  It is also sometimes necessary to have multiple default
gateways on the same vlan for load balancing or traffic engineering.
RA/auto configuration is incompatible with all but the most trivial

- Kevin

Ray Soucy

Epic Communications Specialist

Phone: +1 (207) 561-3526

Networkmaine, a Unit of the University of Maine System

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