Network Topology

[InlineFour]

who/what do ISPs network with?

 

[spidey07]

a collection of routers and transport gear designed in a hierarchial manner normally formed of 4 layers - core, distribution, edge and customer edge.

this single autonomous system under a single routing authority then peers/shares reachability information with other autonomous systems to form what is called the Internet.

 

[Woodie]

betting that Inline won't understand THAT answer! 😉

Heck, I had to slow down my reading in order to get it all! 😱

 

[blemoine]

Spidey07: Do you really expect anyone to believe all that mumbo jumbo & nonsense?

Inlinefour. They network with magic network elves that move faster than the speed of light and personally handle every network request. Thats how they know if your doing something illegal or not. and that my friend is the truth.

 

[spidey07]

Well I tried to give an "easy" answer. even defined what an autonomous system is.

oh well.

 

[MrDudeMan]

Originally posted by: blemoine
Spidey07: Do you really expect anyone to believe all that mumbo jumbo & nonsense?

Inlinefour. They network with magic network elves that move faster than the speed of light and personally handle every network request. Thats how they know if your doing something illegal or not. and that my friend is the truth.

please explain what was not to be believed. his answer was accurate and concise. if you didnt understand the vocabulary or concept, that doesnt give you the right to hate on him. he definitely knows what he is talking about.

inline, they connect together through a series of high speed routers all over the world. the topologoy, IIRC, is a star network, meaning every router is connected to every other router so if one fails an alternate route can be established. each ISP is part of a MAN (metropolitan area network) and also has its own LAN (subscribers). as far as the topology in a city for each ISP, i have no clue but i would imagine there is at least minimal redundancy.

basically there is no single entity we all connect to and call the internet. in classes it is usually denoted as the "cloud" from which connectivity is established.

 

[spidey07]

Well this could be fun.

Let's talk network design and topology?

topology is a misnomer in large scale networking, like the Internet. It has a meaning but not in the same terms of bus/star/ring that is normally associated with LAN technologies.

If I were to try and put it in those terms it would be a "distributed ring"

I tried my best to describe the layers involved because that it how network are built. You have a true "core" - this is the collection of routers connected by very high speed links (multiple OC-48, OC-192) to send packets as fast as they can over long distance. For example AT&T's presence in north america is a core of maybe 20 or less routers.

Speaking of distance, this is the responsibility of the transport layer. I mentioned this in my post. That layer doesn't do anything more then send bits as fast as possible - there isn't much intelligence there. That layer is there to carry and synchronize the movement of bits and present clock...think of it as layer1....think of it as a cloud....your put bits in and the bits come out the other end. A black box if you will. This is the arena of SONET - transport.

That's it for now, but this thread could get real interesting real quick.

Anybody always wonder why the OSI model/layers are pounded into your head beyond oblivion? Because it is the single most driving factor in networking and design above all else.

 

[MrDudeMan]

Originally posted by: spidey07
Well this could be fun.

Let's talk network design and topology?

topology is a misnomer in large scale networking, like the Internet. It has a meaning but not in the same terms of bus/star/ring that is normally associated with LAN technologies. For example AT&T's presence in north america is a core of maybe 20 or less routers.

If I were to try and put it in those terms it would be a "distributed ring"

I tried my best to describe the layers involved because that it how network are built. You have a true "core" - this is the collection of routers connected by very high speed links (multiple OC-48, OC-192) to send packets as fast as they can over long distance.

Speaking of distance, this is the responsibility of the transport layer. I mentioned this in my post. That layer doesn't do anything more then send bits as fast as possible - there isn't much intelligence there. That layer is there to carry and synchronize the movement of bits and present clock...think of it as layer1....think of it as a cloud....your put bits in and the bits come out the other end. A black box if you will. This is the arena of SONET - transport.

That's it for now, but this thread could get real interesting real quick.

Anybody always wonder why the OSI model/layers are pounded into your head beyond oblivion? Because they are the single most driving factor in networking above all else.

:thumbsup: i have limited knowledge of this stuff but i have a good understanding of how it works. sorry, i didnt mean to use the wrong words...but i dont know the right ones. its been a while since ive even discussed it with anyone or been in a class 😛

on another note, however, i have been designing faster transistors to make data migration faster, so maybe when organic thin film semicondutors go commercial we can work on latency issues.

 

[spidey07]

Well when talking "topology" of an ISP no matter who they are you're really talking "reachability and routing"

It is not dissimilar to call routing with a telephone, within your first few presses of the button the call has already hooked up with the switch that will handle your call.

Like I said, it gets real complicated....REAL quick. And to say the least data networks are modeled by what we learned from voice networks and still models the the same methodology.

The Internet is nothing more than a global message delivery services, the ISPs are nothing more than postal service. but we/they deal in milliseconds and not days.

 

[blemoine]

mrdudeman: That is what we like to call sarcasism. i totally believe everything Spidey07 said. Spidey07 is one of the most helpful and knowledgeable people on this board.

 

[MrDudeMan]

Originally posted by: blemoine
mrdudeman: That is what we like to call sarcasism. i totally believe everything Spidey07 said. Spidey07 is one of the most helpful and knowledgeable people on this board.

oh really? what is this "sarcasm" thing you speak of? :roll:



spidey, on the most "zoomed" out scale, how many devices are used for the central data path around the world? is it appropriate to call them routers and if so how many exist?

 

[spidey07]

A router does nothing but route. But as a guess take the number of routes on the internet and that would be a good guess.

Looks like the Internet routing table is at 178,000 networks/prefixes. These are actively announced routes/paths on the internet. Basically a router saying "hey, wanna get here? Here's how"

If I were to take an educated guess at "main path" routers....probably a couple thousand.
----output from a well known route server, cookie for anybody that knows who owns it....c'mon, it should only take you a few seconds *cough* 12. *cough*---------

oh, and end the drama please...we're all friends here. Plus it's been awhile since I've been deep into BGP so talking about it helps jog the mind.


route-server>sh ip bgp sum
BGP router identifier 10.1.2.5, local AS number 65000
BGP table version is 9540424, main routing table version 9540424
178820 network entries using 18060820 bytes of memory
3397354 path entries using 163072992 bytes of memory
41447 BGP path attribute entries using 2321816 bytes of memory
37440 BGP AS-PATH entries using 971332 bytes of memory
4 BGP community entries using 96 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 184427056 total bytes of memory
Dampening enabled. 2147 history paths, 499 dampened paths
178614 received paths for inbound soft reconfiguration
BGP activity 288940/110120 prefixes, 9392009/5994655 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
10.0.0.2 4 7018 0 0 0 0 0 never Idle (Admin)
12.0.1.63 4 7018 2932482 71199 9540404 0 0 7w0d 0
12.123.1.236 4 7018 1976464 71198 9540418 0 0 7w0d 178699
12.123.5.240 4 7018 2035050 71199 9540418 0 0 7w0d 178695
12.123.9.241 4 7018 2006059 71201 9540418 0 0 3w6d 178699
12.123.13.241 4 7018 2452605 71202 9540418 0 0 3w6d 178702
12.123.17.244 4 7018 2046156 71199 9540418 0 0 7w0d 178696
12.123.21.243 4 7018 2270460 71199 9540418 0 0 7w0d 178697
12.123.25.245 4 7018 2590910 71199 9540418 0 0 7w0d 178700
12.123.29.249 4 7018 2107890 71199 9540418 0 0 7w0d 178696
12.123.33.249 4 7018 2667659 71198 9540418 0 0 7w0d 178694
12.123.37.250 4 7018 2882204 71201 9540418 0 0 3w6d 178699
12.123.41.250 4 7018 2306119 71199 9540418 0 0 7w0d 178700
12.123.45.252 4 7018 2580638 71202 9540418 0 0 3w6d 178702
12.123.133.124 4 7018 2045452 71198 9540418 0 0 7w0d 178702
12.123.134.124 4 7018 2164216 71201 9540418 0 0 3w6d 178701
12.123.137.124 4 7018 2447154 71201 9540418 0 0 3w6d 178695
12.123.139.124 4 7018 2358867 71198 9540418 0 0 7w0d 178701
12.123.142.124 4 7018 2614348 71198 9540418 0 0 3w6d 178702
12.123.145.124 4 7018 2692404 71199 9540418 0 0 3w6d 178699

 

[randal]

yay for the AT&T route server!

 

[spidey07]

Originally posted by: randal
yay for the AT&T route server!

Randal gets the cookie!!!!!!!!!!!!!!!!!!!


good job

 

[randal]

I hope that, for the sake of the Internet, SBC/AT&T/Southwestern/Whoevertheyarethisweek leaves that route-server in place. Much like the previously discussed 4.2.2.1/2 name servers that Verizon runs, it would be a sad day if they went down.

 

[spidey07]

yep, there are tons of route-servers out there.

But that's where I go first to get "the real deal"

 

[n0cmonkey]

Has anyone messed with OpenBSD's OpenBGPd? It looks like DE-CIX is looking to upgrade to it. Slides from a presentation on it.

 

[spidey07]

Originally posted by: n0cmonkey
Has anyone messed with OpenBSD's OpenBGPd? It looks like DE-CIX is looking to upgrade to it. Slides from a presentation on it.

hey unix bigot. Let the network take care of the network, let your hosts be hosts. Big rule in network design.

😉

I get into this all the time with unix bigots so please do tell me why a host should be actively involved with routing????

Gee, because we do it in hardware/asic and you don't because you can't without a unix box the size of a fridge. that damn OS overhead and all.

-ps- i am fully aware that at the core of IOS it is a unix kernal running things.

 

[crashish]

Configure a "host" with the proper hardware and software to be a "network" and suddenly you no longer have a "host". That's pretty much how Cisco started off, so what's the problem with doing that now?

 

[spidey07]

Originally posted by: crashish
Configure a "host" with the proper hardware and software to be a "network" and suddenly you no longer have a "host". That's pretty much how Cisco started off, so what's the problem with doing that now?

ASIC - it's all done in hardware now. At the speeds today a processor based system can't cut it.

But you're right. A router is nothing more than a super fast host that routes. But doing it in programmable hardware is best IMHO. Plus there is that whole design aspect - never let a host or end node do routing....leads to bad mojo.

 

[crashish]

Originally posted by: spidey07

Originally posted by: crashish
Configure a "host" with the proper hardware and software to be a "network" and suddenly you no longer have a "host". That's pretty much how Cisco started off, so what's the problem with doing that now?

ASIC - it's all done in hardware now. At the speeds today a processor based system can't cut it.

Tell that to the ISPs who use such systems. I'm sure they (we) will be shocked to hear it.

 

[crashish]

Originally posted by: n0cmonkey
Has anyone messed with OpenBSD's OpenBGPd? It looks like DE-CIX is looking to upgrade to it. Slides from a presentation on it.

I haven't tried OpenBGPd yet, but it seems like a bit of a step forward in some respects at least. Quagga appears to be the most popular (and it's what I've been using) and of course there's XORP which has been mentioned on Slashdot.

 

[MrDudeMan]

Originally posted by: crashish

Originally posted by: spidey07

Originally posted by: crashish
Configure a "host" with the proper hardware and software to be a "network" and suddenly you no longer have a "host". That's pretty much how Cisco started off, so what's the problem with doing that now?

ASIC - it's all done in hardware now. At the speeds today a processor based system can't cut it.

Tell that to the ISPs who use such systems. I'm sure they (we) will be shocked to hear it.

out of curiousity, what is your position at your company?

 

[spidey07]

Originally posted by: crashish

Originally posted by: spidey07

Originally posted by: crashish
Configure a "host" with the proper hardware and software to be a "network" and suddenly you no longer have a "host". That's pretty much how Cisco started off, so what's the problem with doing that now?

ASIC - it's all done in hardware now. At the speeds today a processor based system can't cut it.

Tell that to the ISPs who use such systems. I'm sure they (we) will be shocked to hear it.

that's cool. You're one of "those guys" and I'm one of "those guys"

the debate over who has the "best" routing solution between the network guys and the OS guys will go on forever I believe. There are great merits to both sides.

It is a similar to a live forum that I recall - the gigabit ethernet vs. ATM. Excellent points presented by both sides. Just as there are great points presented in the unix vs. network hardware debate.

From what I see it is split currently. I would be more than happy to hear another viewpoint...as we/I have tried to keep this thread on track.

So seriously, I would like to learn about the other side and I'm not waving an e-penis here. Could you maybe touch upon the current state of ISPs and the use of unix vs. hardware IOS/JunOS.

I know it sounds like a "bait" but in all honesty I would really love to hear your opinion on the industry. Mainly because it changes so quickly.

[/b]I value your opinion so do please respond. Like I said earlier, this thread could get real fun if we stay open and I'm sure others could learn.[/b]

-edit- what I mean is this category could use a healthy dose of serious large scale discussion.

signed and confirmed "network bigot"
😉

 

[crashish]

Originally posted by: MrDudeMan

Originally posted by: crashish

Originally posted by: spidey07

Originally posted by: crashish
Configure a "host" with the proper hardware and software to be a "network" and suddenly you no longer have a "host". That's pretty much how Cisco started off, so what's the problem with doing that now?

ASIC - it's all done in hardware now. At the speeds today a processor based system can't cut it.

Tell that to the ISPs who use such systems. I'm sure they (we) will be shocked to hear it.

out of curiousity, what is your position at your company?

"It's complicated." (I wear an inordinate number of hats at the moment.)

The point of the post, though, is that a number of operations use software-based solutions such as Quagga and the like with great success.

Equipped with beefy-enough hardware, I have seen Quagga boxes handle multiple 100mb links at or near saturation without falling over. I have not personally seen any gigabit setups but I have heard of some positive results in test labs at the very least.