Most likely there’s also some historic reason why it was implemented this way.
BGP synchronisation is also one example where default was at early days to 
and nowadays not to synchronise.
Hot-potato routing can definitely be the reason for such a low AD for eBGP.

And, as we nowadays run anycast services quite often we luckily have the BGP 
backdoor option to use
to avoid the hot-potato if needed.

Jorma Mellin
SIY ry / ISOC Finland Chapter
ENISA PSG member
(tel. +358 50 9944762)

> On 11 Apr 2018, at 12:36, Maximilian Wilhelm <> wrote:
> Anno domini 2018 Hank Nussbacher scripsit:
> Hi,
>> While giving a routing lecture today someone asked me
>> "Why was eBGP assigned an administrative distance of 20 which is better
>> than OSPF's administrative distance of 110.  What was the logic behind
>> that decision?"
>> I was unable to think of an answer.
>> Ideas?
> As eBGP usually is a connection to some elses network, and OSPF only
> is internally to your network, the idea is to get packets away to
> someone else (-> the destination) as fast/early as possible and avoid
> transporting the traffic in your own network if there is an exit.
> Best
> Max
> -- 
> Friends are relatives you make for yourself.

Reply via email to