1. Prepending by itself isn’t bad. Prepending past the point that it is effective in accomplishing anything is what you generally want to avoid. Even then, it’s not nearly as big a deal as some make it out to be in most cases. 

2. De-aggregation has it’s uses and it’s place. Have a /20 , but announcing all the component /24s, even though you aren’t doing anything different with any of those? Bad practice. You’re just polluting the global table size for no good reason.  However, perhaps you have a set of hosts in a single /24 that you want to try and protect from a prefix hijack. Announce the /20 and that singe /24. Not perfect protection , but provides some cover, and isn’t that big a deal. 

The answers to all of these questions are really : “It depends on what you are trying to do.” There are generally accepted solutions to certain problems, and there are plenty of dumb solutions that are the only thing possible due to circumstances, so sometimes that’s what you have to do too.

Don’t worry about the pitchforks so much. :)   

On Thu, Oct 20, 2022 at 08:15 Pirawat WATANAPONGSE via NANOG <nanog@nanog.org> wrote:
Dear all,


Before all else:
thank you all for the lightning-fast responses (even taking the time zone advantage into account).
I really, really, really appreciate all your recommendations.

Virtually all of you recommend prepending as the first choice.
I also get the feeling that you guys consider de-aggregation “distasteful” (at the least) but sometimes unavoidable.

I have considered the prepending myself, but dare not implement it yet
for the fear that BGP (Human) Community will burn me alive, witch-hunt style,
because of the following reasons:
1. I can see from looking glass(es) that my upstreams already practice prepending (some paths) at their level (at least 3 more hops [x4]), supposedly to “balance” their bandwidth.
2. Should I start prepending mine, I might upset their balance, causing them to prepend more, thus starting a “prepend war”. [I imagine that x20+ prepending starts out this way]

The way I see it, prepending (or maybe even the whole BGP-Path thing) is a local-optimization problem: it’s only best for someone, not globally.
And the Higher-Tiers (Lower Tier-Numbers) will always “engineer” me in the end.

Worse yet, I might be out-voted by de-aggregation insider “cultists” anyway.

Which forces me to proactively ask you guys questions about ROV-Overlapping and ROV “Hijack Gap” soon, in another posting with separate “Subject:”.

Again, Thank you.


Cheers,

Pirawat.


P.S.  [Off-Topic] Any comment on the “SCION” System?
Any good (I will even take "academically")?
[Reference: https://scion-architecture.net/]