>> a tier-1 network does not get transit prefixes from any other >> network and peers with, among others, other tier-1 networks. >> >> a tier-2 gets transit of some form from another network, usually but >> not necessarily a tier-1, and may peer with other networks. >> >> this does not please everyone, especially folk who buy transit and >> don't like discussing it. and there are kinky corners > Even this is debatable (& I know you know this Randy).
in this forum, everything is debatable. some portion of the debate makes sense. ymmv. > Firstly, peering isn't binary. Is peering vs transit a distinction based on > routes taken / accepted & readvertised, or on cost? Does "paid for peering" > count as peering or transit? If you pay by volume? If you pay for "more > than your fair share" of the interconnect pipes? (if the latter, I am > guessing there are actually no Tier 1s as everyone reckons they pay for > more than their fair share...). pay? did i say pay? i discussed announcement and receipt of prefixes. this was not an accident. it is measurable. > Secondly, it doesn't cover scenarios that have have happened in the past. > For instance, the route swap. EG Imagine networks X1, X2, X3, X4 are "Tier > 1" as Randy describes them. Network Y peers with all the above except X1. > Network Z peers with all the above except X2. Y & Z peer. To avoid Y or Z > needing to take transit, Y sends Z X2's routes (and sends Z's routes to X2 > routes marked "no export" to X2's peers), and Z sends Y X1's routes (and > sends Y's routes to X1 marked "no export" to X1's peers). Perhaps they do > this for free. Perhaps they charge eachother for it and settle up at the > end of each month. Perhaps it's one company that's just bought > another. seems to me that, if you look at the prefixes, it's pretty clear. randy