[ih] TTL [was Exterior Gateway Protocol]

[Vint Cerf]

others closer to ops may have better opinions but I think hop count has
helped to detect loops.
v


On Fri, Sep 4, 2020 at 7:05 PM Brian E Carpenter via Internet-history <
internet-history at elists.isoc.org> wrote:

> So, here's another history question:
>
> On 05-Sep-20 05:11, Tony Li via Internet-history wrote:
> ...
> > Topology.
> >
> > Strictly speaking, AS-level routing is not necessary. You can do
> everything with other protocols and leaking/redistribution except that:
> >
> > - No protocol other than BGP can support Internet (or service provider)
> route scale.
> >
> > - Leaking/redistribution has no loop prevention mechanism.
>
> I was taught many years ago that the TTL field (renamed Hop Limit in IPv6)
> was intended only as a last resort method of loop prevention.
>
> a) Is that accurate?
> b) Has it ever saved the Internet?
>
> (It does have one slightly bizarre use today: check that it's still 255 to
> detect forwarded link-local packets, and there's also RFC5082.)
>
>     Brian
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>


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