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Who determines peering partners?
Lets say you traceroute/tracert an address. Who determines if it's routed through say Level3, NTT, HE.net, CogentCO, Zayo, etc.
Does the destination provider/host/isp determine the route taken or does the originators network?
If the originator of the request decides based on what peering is paid for, then why would some destinations be given to CogentCo and another to Level3, despite lets say Cogent having many more hops? Or why not just route everything via Level3 or He.net and use Cogent and Zayo for fail-over? Seems like the current solution is quite convoluted and I can't figure out who designates what route/provider/partner to take.
Thanks.
Thanked by 1vimalware
Comments
Both ends can decide.
-_-.... That's even more confusing...
You can have outbound all through cogent and inbound all through ntt for one example. You can have route optimiser software make it so that on weekends, the lowest cost transit provider is the only one used, etc.
In this scenario are you announcing to the other party that you only will receive via NTT? at what point then does the other party's data get passed off to NTT? What if the other parties provider doesn't peer with NTT (pay for NTT peering).
When does cost come into play? Who's covering the expense when your receiving via NTT and sending out Cogent? Do both parties end up paying for Peering?
Peering and transit are two entirely different things cost-wise.
You receive via NTT: you pay for bandwidth. You send via Cogent: you pay for bandwidth.
If the other party does not use NTT, they use another provider that connects to NTT, most likely, and gets handed off there (like x -> telia -> ntt -> y). x will pay for the telia portion, you pay for the ntt portion. If both of you use ntt, then I would probably expect both x and y pay for ntt.
Interesting. Thanks for the insight that was very clear.
Any idea on the pricing differences? I've heard Level 3 to be the best and cogent to be the ruler of budget (although in my experience HE.net is far better than cogent). But whats the difference in price there for some of our hosts here? If they are transferring lets 30tb a month (max 100mbps 24/7) with level3 vs cogent
Providers like NTT, GTT; Cogent, Level 3, (HE) and others are considered Tier-1s, they have (free) peerings between each other to ensure global reachability.
I would not say Level 3 is "the best". It depends very much on what you want to achieve, eg. if you are a hosting provider it depends on who your customers are and also where the audience is.
Level 3 might be a good fit for US Customers but not for EU Customers. If you are primarily active in the EU you might want to go with Telia. Or if you just want "big fat pipes" get Cogent + HE.
As said, as a network operator you can to influence the path a packet is coming. You want to do this especially if you have multiple Upstreams, Peering and Paid Peerings.
You might want to steer the traffic a certain way to leverage someone into a (free) peering, like push all Traffic to B over a for him expensive Transit provider.
True, Cogent is cheap, right up with HE. If you get transit from one of those it's not measured in TB rather in Gbit/s. 1Gbit/s Transit from HE or Cogent will cost you ~300$/m iir, depending on Location and negotiation. That's like 0.3$ per Mbps, if you commit to like 100Gbit/s this can go as low as like 0.09$/Mbps.
I don't know Level 3 pricing but you can expect it to be much higher, so as a host you would want to drop as much as possible over a cheap one like Cogent..
Cogent is not bad, neither is HE. They both have their strong points. On IPv6, HE is your go-to provider, for IPv4, not so much.
If you like to read, http://drpeering.net/tools/HTML_IPP/chapters/ch02-Internet-Transit/ch02-Internet-Transit.html
Not that new but a good source if you want to read about transit and peering strategies
Billing is 95th percentile usually, not per GB, and which carrier being the best often varies heavily based on where you plan on going
There's no such thing as a "best" carrier. All of them have pros and cons.
For example, I have a strong distaste for Cogent. The network is quite bad from my experience and their sales reps are bloody annoying. BUT, they're cheap as chips.
HE is OK. They're a bit better than Cogent network-wise thanks to their "we want to peer with EVERYONE" policy. They also provide free IPv6 transit (and I mean FREE). But you can't control routing within HE's network (no communities) which makes them a pain in the ass if you have multiple transit providers and want to do any sort of optimizations.
The thing is, both of these could be "best" for a seedbox or a low end provider. You will get usable connectivity from both of these. Would I operate a CDN singlehomed to any of those though? Never.
The outbound path is decided separately from the inbound path.
Starting with outbound, your closest router looks at the BGP routing table for the ip you want to reach. It looks at all the options being advertised from neighboring routers.
From my experience, most routers seem to prefer a a route that goes through a peer first so they don't have to pay for the traffic. If they send the data through paid transit, then they have to pay for bandwidth.
Then it will prioritize routes by picking the one with the shortest ASN count.
You can see a more complete list here https://www.noction.com/blog/bgp_bestpath_selection_algorithm
You can influence the inbound path by picking which transit providers you advertise to, adding BGP communities, and padding the ASN list with your ASN to deprioritize certain routes.
You guys are awesome! I knew I add posting the right question to have right sub. Thanks for taking the time to educate me future on a subject that's frankly pretty hard to get concrete info on unless you're a datacenter or large scale colocator .