Hi there,
I have been working on characterizing the internet hierarchy.
I noticed that 27% of the total possible tier-2 provider node pairs are
not
connected i.e., they dont have any tier-1 node connecting them nor a
direct peering link between them.
Multihoming can be used as a predominant reason for the
reachability
of tier-3 nodes which are customers of these nodes, but what about the
reachability of tier-2 nodes themselves and its customers which cannot
afford to multihoming? How does BGP solve this reachability problem when
it gets a request to a prefix unreachable?
1 tier-1
/
2 4 tier-2
/ \ / \
5 6 7 8 tier-3
here, nodes 2 and 4 have no reachability,
1
/ |
2 3 4
/ \ \/ \
5 6 7 8
now, node 7 is reachable from 2 and its lower level nodes, but what
about
node 4 and 8, and as a typical case, suppose nodes 4 and 8 have no
multihoming whatsoever, what then?
I have been working on characterizing the internet hierarchy.
I noticed that 27% of the total possible tier-2 provider node pairs are
not
connected i.e., they dont have any tier-1 node connecting them nor a
direct peering link between them.
It's quite simple. The Internet is not a tree hierachy;
it is a partial mesh. Partial meshes can often be characterised
as having some sort of hierarchy of connectedness, however
the Internet does change continuously which means that an
analysis of hierarchy done today will come up with different
results from last year's analysis.
The terminology of "tier 1" and "tier 2" only refers to
a brief time in the evolution of the Internet in North
America during the 1990s when the topology was much
more treelike. That is all changed.
Go to google and search the following line exactly as written.
"internet topology" "partial mesh"
I think that likely you're looking at partial data (well i am sure you are, since i'm part of the internet and you didn't' get routing data from me...) and not seeing paths because of that. The BGP tables of a single node list all outward paths to other places. Thus from a single sample point it is totally impossible to 'map' the internet.
I think that likely you're looking at partial data (well i am sure you are, since i'm part of the internet and you didn't' get routing data from me...)
Duh !
and not seeing paths because of that. The BGP tables of a single node list all outward paths to other places. Thus from a single sample point it is totally impossible to 'map' the internet.
Not to mention the *constant* change in routing.
Actually, I am not doing what you think I am. I am using the RouteViews aggregation of the BGP routing tables. RouteViews is a project at the univ. of Oregon that peers with backbones and other ASes at interesting locations so as to make it as comprehensive as possible. Also, it updates the data every 2 hours of everyday. So, I am looking at almost full and fresh data :>
i don't thing an operator or seasoned researcher would characterize
route-views or ripe ris as "almost full" data. they provide such a
small and narrow peek as to require great caution when dealing with
them. considering the topologies you suggest, folk may legitimately
wonder if perhaps you have not exercised sufficient caution.
I think that likely you're looking at partial data (well i am sure you are, since i'm part of the internet and you didn't' get routing data from me...)
Duh !
Not nice to make fun of people who are trying to help you.
and not seeing paths because of that. The BGP tables of a single node list all outward paths to other places. Thus from a single sample point it is totally impossible to 'map' the internet.
Not to mention the *constant* change in routing.
Actually, I am not doing what you think I am. I am using the RouteViews aggregation of the BGP routing tables. RouteViews is a project at the univ. of Oregon that peers with backbones and other ASes at interesting locations so as to make it as comprehensive as possible. Also, it updates the data every 2 hours of everyday. So, I am looking at almost full and fresh data :>
Unfortunately, the paragraph above shows me that there are errors in your base assumptions about how the Internet works. A couple of people have tried to point this out to you, you should listen instead of telling them why they are wrong.
It is bad to base conclusions on incorrect assumptions. It is even worse to assume those of whom you ask for help know less than you do about the topic at hand.
I am very sorry that you spent a lot of time probably doing good work digging through the route-views archives but have seem to come to false conclusions. It can be difficult to admit hard work has come to a bad end.
However, it might not have been a waste. You seem to have the motivation, time, and energy to research the topic, perhaps your research can be quickly applied to different data, or in a different way? Might I suggest a Google search for past research on Internet topology? I believe the University of Oregon has done some. And CAIDA. And many others. Many are still doing research and happy to collaborate.
> Actually, I am not doing what you think I am. I am using the RouteViews
> aggregation of the BGP routing tables. RouteViews is a project at the
> univ. of Oregon that peers with backbones.
Really? Could you tell us more about it? I thought there was just one
Internet backbone.
Bill... Stop it!!! shooting fish in a barrel is
no sport at all.
> I am looking at almost full and fresh data.
So what value do you assign to "almost full?" There's a difference
between "best" and "complete," which you may not be entirely appreciating.
-Bill
almost full == just after dessert
and as you (and almost every one else on this list) know,
there is zero chance of "complete" ... and "best" is always
in the eye/routing-table of the beholder.
> Actually, I am not doing what you think I am. I am using the RouteViews
> aggregation of the BGP routing tables. RouteViews is a project at the
> univ. of Oregon that peers with backbones.
Really? Could you tell us more about it? I thought there was just one
Internet backbone.
Would you excuse me if I didnt predict that you couldnt improvize and make out of the context?
If you would like some help, please stop, take a deep breath, count to ten slowly, then ask nicely and some people here might teach you something. Woody's sarcasm might have annoyed you, but your repeated flames (and not even good ones!) at the people you asked to help you annoy all of us.
If you do not want any help, you are welcome to continue in your misunderstanding of how the Internet works.
> Actually, I am not doing what you think I am. I am using the RouteViews
> aggregation of the BGP routing tables. RouteViews is a project at the
> univ. of Oregon that peers with backbones.
Really? Could you tell us more about it? I thought there was just one
Internet backbone.
Bill... Stop it!!! shooting fish in a barrel is
no sport at all.
You think I am a fish in a barrel? Well, guess what, I didnt think it through while entering your mouth that you're dumb enough to prefer it rather in a barrel!!
i suspect that, rather than being a sociologist trying to
catorgize operators on the surliness scale, at which you
seem to have succeeded splendidly, you may be tring to
understand AS relationships. you may find a useful paper
trail that kinda goes from
May be you should spend more time on networking than your partime job of
yoga teaching!
Pavan, what you seem to know of networking is not just outdated, its
plain wrong.
And you've just managed to flame some of the people who understand it
well enough to be the among the best teachers of bgp, routing and DNS
that I know of - and I've seen them teach at many a netops conference.
And some others who have enable on huge, worldwide networks that you'd
kill to get an interview call from, let alone a "you're hired" email.
I know that passing the JEE exam to get into an IIT means that you do
have more brains than the average engineering student - so try to
apply them for a change.
Follow that first, original suggestion of googling for "partial mesh",
"peering", etc. Then download some of Philip Smith's elementary bgp
tutorials - google will find those for you too. Finally, google for
the names of the people who have replied to you in this thread.
Till then, do yourself a favor. Go right back to lurking on nanog
I am sorry, am I not ingratiating myself with the good graces of the
father of Internet?!
No. All you are doing is pissing off the people who have been giving
you the right answers. If what they tell you means you have to tear
up a whole paper thats based on wrong assumptions, and start from
scratch, tough. It'll save you the hassle of seeing your prof fling
it right back at your face with an F scrawled on it when you turn it
in.
speaking of hiring .. you'd better pray that your brief foray into
nanog goes unnoticed by people who will be interviewing you for a job
that lets you anywhere near a $90 linksys box let alone cisco or
juniper kit
thank you randy. and for the more energetic, who can
tell me all the BGP relationships w/ AS 4555? (existing
peers and operators of AS 4555 are not allowed to play
And CAIDA. And many others. Many are still doing research and happy to collaborate.