turning on comcast v6

Leo Bicknell bicknell at ufp.org
Mon Dec 30 23:31:37 UTC 2013

On Dec 30, 2013, at 4:37 PM, Victor Kuarsingh <victor at jvknet.com> wrote:

> On Mon, Dec 30, 2013 at 3:49 PM, Lee Howard <Lee at asgard.org> wrote:
>>> The better question is are you using RIP or ICMP to set gateways in your
>>> network now?
>> I disagree that that's a better question.
>> I'm not using RIP because my hosts don't support it (at least, not without
>> additional configuration), and it would be a very unusual configuration,
>> adding weight and complexity for no benefit.  RAs are the opposite.
>> Not even sure how you would use ICMP to set a default gateway.  Maybe
>> there's a field I'm unaware of.
> [VK] The RIP comparison is somewhat confusing to me.  I don't see how RIP
> is comparable in this context (I guess technically you can pass a default
> route in RIP, but as Lee mentions, the protocol is designed for a different
> purpose and requires configuration).

There was a time, I'm going to roughly guess approximately 1987-1992, although
I may be off by a year or two, that you needed to have lived through for this
to make sense.

You see, in that time the available IGP was, well, RIP.  RIPv1.  Routers, at
least ones you could buy, did not have OSPF, EIGRP, or even in many cases
EGP/BGP.  They had RIPv1, and perhaps some bleeding edge Cisco's had IGRP.
So almost every campus network ran RIPv1.

This is also pre-CIDR, so remember every subnet had to have the same mask.
For instance the University I went to had a /16, divided into entirely
/22 networks for each LAN.  The RIP config enabled it for the entire /16.

Certain vendors, like Sun (who was popular at the time) shipped SunOS boxes
with routed enabled by default, where they received a default route (if
the admins filtered) or a full (local) table via RIPv1.

In short, there was a time when getting a default route via RIP was in
fact common.  It was also the time of telnet, and rsh, decidedly pre SSL,
ssh, or IPSEC.

It was also a time when the Internet came under heavy, well, attack, by people
who realized how soft and squishy it was.  Injecting a route into RIP
allowed you to hijack rsh sessions, for example.  Lots of people who were
admins at that time learned through personal pain and late night hacking 
that sending a dynamic route to a box via an unauthenticated protocol was
a recipe for disaster.

       Leo Bicknell - bicknell at ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/

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