[ih] TTL [was Exterior Gateway Protocol]

[Louis Mamakos]

One could argue that traceroute saves the Internet pretty much every 
day.

On 4 Sep 2020, at 19:19, Guy Almes via Internet-history wrote:

> Brian,
>   It did give us traceroute.  Not quite saving the Internet, but it 
> was wonderful,
> 	-- Guy
>
> On 9/4/20 7:05 PM, Brian E Carpenter via Internet-history 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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