Apology: [Re: Tier-2 reachability and multihoming]
This is with my deepest regrets that I apologize from the bottom of my heart to Mr.Gilmore, Mr.Woodcock, Mr.Bush and also the rest of the honourable members of the list for being ignorant of how high-profile a list this is. I couldn't be more sorry. Please, please forgive me. ps: I sure meant no harm, was just trying to be humorous,(I hope the exclamation marks might have given some hint) anyway it is too late. They say there is no natural punishment than remorse. Also, I was too embarrassed to post a quick apology. Thanking you, pavan.
--On Saturday, March 26, 2005 11:51 AM +0530 G Pavan Kumar <pavanji@cse.iitb.ac.in> wrote:
This is with my deepest regrets that I apologize from the bottom of my heart to Mr.Gilmore, Mr.Woodcock, Mr.Bush and also the rest of the honourable members of the list for being ignorant of how high-profile a list this is. I couldn't be more sorry. Please, please forgive me.
ps: I sure meant no harm, was just trying to be humorous,(I hope the exclamation marks might have given some hint) anyway it is too late. They say there is no natural punishment than remorse. Also, I was too embarrassed to post a quick apology.
No exclamation points indicate yelling, animated, surliness, or a host of other emotions, humor is NOT one of them. If you intent was to joke or in jest then don't use !. use ;) or :) esp. since your second language is pretty clearly english where what you're typing, and what we're reading/getting can be hard to interpret.
Thanking you, pavan.
-- Undocumented Features quote of the moment... "It's not the one bullet with your name on it that you have to worry about; it's the twenty thousand-odd rounds labeled `occupant.'" --Murphy's Laws of Combat
So anyway, this internet thing.. forget this concept of tier1, 2, 3 .. they are little more than terms used by salesmen. instead assume all ISPs have connectivity to the whole internet, and that you're a new ISP wanting connectivity of your own. you can buy transit from any ISP and you will get global reachability, you could also buy from any two hence multihoming and have the same global reachability now you're up and running, consider peering.. peering with another isp will give you access to that isp and their customers (ie other isps buying global reachability as you are doing) so as per your original query, if any two nodes/asns dont have a direct connection you can assume one or both is relying on their upstream to provide the necessary global connectivity now, i see your data is from oregon.. i think theres around 50 'views' of the internet from about 25 ASNs. consider there are about 20000 active ASNs currently. you would need to get all 20000 routing tables in order to see exactly what relationships are active. (the reason is that from any single ASN the internet will appear to you as a tree much like your original email, showing the 'up-down' relationships but not the 'left-right' ones) also, in the context that you use 'multihoming' you're really referring to a leaf node such as an enterprise which may buy from 2 or 3 isps to have global connectivity with some redundancy. if you are looking at transit ISPs (ie tier1, 2 in your description) their connectivity is more complicated and you need to continue your reading with some of the suggested papers.. Steve On Sat, 26 Mar 2005, G Pavan Kumar wrote:
This is with my deepest regrets that I apologize from the bottom of my heart to Mr.Gilmore, Mr.Woodcock, Mr.Bush and also the rest of the honourable members of the list for being ignorant of how high-profile a list this is. I couldn't be more sorry. Please, please forgive me.
ps: I sure meant no harm, was just trying to be humorous,(I hope the exclamation marks might have given some hint) anyway it is too late. They say there is no natural punishment than remorse. Also, I was too embarrassed to post a quick apology.
Thanking you, pavan.
forget this concept of tier1, 2, 3 .. they are little more than terms used by salesmen.
at least t1 and t2, also permeate academic papers where the real topology is actually measured. but we should not let demonstrable measurements get in the way of our defense of the position of our smaller networks by marketing people. randy
On Mar 26, 2005, at 11:21 PM, Randy Bush wrote:
forget this concept of tier1, 2, 3 .. they are little more than terms used by salesmen.
at least t1 and t2, also permeate academic papers where the real topology is actually measured. but we should not let demonstrable measurements get in the way of our defense of the position of our smaller networks by marketing people.
And how, pray tell, does one actually "measure" T1 vs. T2 networks? (Assuming you are not talking about two of the Terminator movies. ;-) If someone is paying Network A, but sends communities to be treated as a peer, are they T1 or T2? If someone buys from Network B, but peers with all of Network B's peers, and therefore does not appear in a path through Network B in those peers' BGP tables (except at the actual peering router), are they T1 or T2? If someone "peers" with Network C, but is out-of-balance and pays a settlement fee every month, are they T1 or T2? Assume someone else is out-of-balance with Network C, but in the other direction, does that make Network C a T2? Even if the network in question still pays Network C? Etc., etc., etc. There might be a way to define "Tier 1" and "Tier 2" sufficiently well as to disambiguate all the variations, but I do not think you could do it without seeing (NDA'ed) contracts and/or actual router configurations - neither of which are likely without the help of the network in question. And if you have their help, you can just ask. :-) Back on a more operational topic, it really doesn't matter what "tier" you are, it just matters how good your connectivity is. There is no need to 'defend' the 'smaller networks'. Some of the "tier 1" networks have totally suck ass connectivity. (Yes, 'suck ass' is a technical term. =) -- TTFN, patrick
On Sun, 27 Mar 2005, Patrick W Gilmore wrote:
On Mar 26, 2005, at 11:21 PM, Randy Bush wrote:
forget this concept of tier1, 2, 3 .. they are little more than terms used by salesmen.
at least t1 and t2, also permeate academic papers where the real topology is actually measured. but we should not let demonstrable measurements get in the way of our defense of the position of our smaller networks by marketing people.
And how, pray tell, does one actually "measure" T1 vs. T2 networks? (Assuming you are not talking about two of the Terminator movies. ;-)
i would agree it is possible to mark some networks as transit free - tier1 - and therefore any network using a tier1 to access another tier1 is tier2. arguably a tier3 would be a network not connected to a tier1.
If someone is paying Network A, but sends communities to be treated as a peer, are they T1 or T2?
imho: T1, forget the money <other points snipped, i largely agree :)>
Back on a more operational topic, it really doesn't matter what "tier" you are, it just matters how good your connectivity is. There is no need to 'defend' the 'smaller networks'. Some of the "tier 1" networks have totally suck ass connectivity. (Yes, 'suck ass' is a technical term. =)
absolutely!! it amazes me how much value is placed in this 'tier' system, why not just buy connectivity that (a) is compatible with your size as an ISP (b) reliably delivers bits from A to B Steve
here is what i answered a private message on the subject, with a typo corrected. [un]fortunately, i seem not to have saved the follow-on mess age where i suggested how one could get a good first cut at this from route-views data. randy --- From: Randy Bush <randy@psg.com> Date: Sat, 26 Mar 2005 22:17:03 -0800 To: a nanogian Subject: Re: Apology: [Re: Tier-2 reachability and multihoming]
...which I read to mean you believe there is a measurement or a demonstration (performance-wise or topology-wise) to support at least two classes of networks. I'm not arguing, but I am curious since you are indicating you believe its demonstrable.
read, for example, the paper trail i cited earlier in this thread.
What measures do you believe are most indicative of a "better" network?
better? i did not say better. a simple way to look at it, which we have repeated here every year since com-priv migrated here is 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 (if i have the bad taste to tunnel through someone, that is not transit). but it does not make one network 'better' than another. for our biwa office (where my employer has no presence), the best network is one where i know the ceo, so can get something fixed if i need to panic and the csr does not cut it. randy
--On 27 March 2005 12:59 -0800 Randy Bush <randy@psg.com> wrote:
better? i did not say better. a simple way to look at it, which we have repeated here every year since com-priv migrated here is
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). 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...). 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. All this come down to the fact that "Tier n" is not a useful taxonomy because there is no clear ordering of networks. If I was really pushed for a definition, I'd say it was this: you are a Tier-1 network, when, if you tell all third parties not to advertise your routes to anyone but their customers, and you get a phone call from one of your customers complaining about a resultant connectivity problem, you can be confident before you've analyzed it, that the customer will accept it's that networks problem, not yours. This boils down to "does the customer believe you". Alex
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
On Mon, 28 Mar 2005, Randy Bush wrote:
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.
i also avoided money.. i dont think its that relevant, everyone is paying for peering or transit in one form or another, i dont think any peering is free (free != settlement free)
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.
"transit (n). The act of passing over, across, or through; passage." whether it is a settlement arrangement or a mutual swap, they do NOT have peering, they ARE transitting and by our definition are not transit-free (and hence not tier1) however alex, you do highlight an excellent point - things are not as simple as 'tier1, tier2', there are complicated routing and financial arrangements in operation, which brings me back to my earlier point: does it matter what a network is paying for some connectivity providing they deliver to you the connectivity you need at the quality you desire? Steve
On Mon, 28 Mar 2005 16:17:21 +0100, "Stephen J. Wilcox" said:
however alex, you do highlight an excellent point - things are not as simple as 'tier1, tier2', there are complicated routing and financial arrangements in operation, which brings me back to my earlier point: does it matter what a network is paying for some connectivity providing they deliver to you the connectivity you need at the quality you desire?
As long as their price point for their connectivity is set such that they can remain a viable ongoing business concern while fulfilling the requirements of my contract, it doesn't really matter, except at contract renegotiation time. At that point, if I know they're making money off selling others transit to my packets, I may try to negotiate a price concession....
And how, pray tell, does one actually "measure" T1 vs. T2 networks?
That's easy. You define a set of criteria by which you can measure the networks on some scale, and then set two thresholds. Networks which exceed the higher threshold are Tier 1, those which only exceed the lower threshold are Tier 2. I have seen people do this by counting the number of ASes that a network connects to. And I have seen this done with nodes by summing up the bandwidth of all circuits connected to a node. Even though the network is a dynamic partial mesh, researchers can learn a lot about the behavior by imposing various types measurement hierachy on the network. Thus, Tier 1 and Tier 2 are not inherent characteristics of the Internet; rather they are characteristics of a particular view of the network at a particular point in time. There are probably people who are trying to measure a hierarchy of latency or a hierarchy of jitter. The more views, the merrier. --Michael Dillon
participants (8)
-
Alex Bligh -
G Pavan Kumar -
Michael Loftis -
Michael.Dillon＠radianz.com -
Patrick W Gilmore -
Randy Bush -
Stephen J. Wilcox -
Valdis.Kletnieks＠vt.edu