Why are latencies to overseas networks so much higher than distance?

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PenultimateHop

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#704113 20-Oct-2012 20:00

Publius:What i've calculated is that maybe 2/3rds of the latency between NZ-US NZ-AS (and im measuring just the latency between the two routers in a traceroute which are on either sides of the undersea cable) is due to physical limitations, but ~1/3rd isn't and it surprises me that its as high as that.

1. Things are unlikely to improve end-to-end latency wise until it is feasible to increase the speed of light inside fiber.
2. You are not measuring what you think you are: "the latency between two routers in a traceroute which are on either sides of the undersea cable". This is just absolutely incorrect.
3. As explained before you are seeing the end-to-end latency to Brisbane due to the topology of the network involved.
4. Don't trust reverse DNS.

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Linuxluver

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#704125 20-Oct-2012 20:25

Publius: I'm wondering if some clueful poeple here can help me.

I've been looking at a few traceroutes from NZ to various overseas destinations and what been bugging me is the times involved with the undersea cable legs.

For example round-trip tracing from Auckland to Sydney (host905.rimuhosting.com)
5. vocus1.ape.nzix.net 3.4
6. ten-0-2-0-400.bdr01.akl01.akl.VOCUS.net.au 43.1

So the real-world one-way distance would be 19.85ms
According to wolfram|alpha "distance auckland sydney" is 10.1ms
According to Southern Cross Networks themselves the auckland sydney cable leg is 11.38ms.

So 19.85 real world, 11.38 for the distance. We have a missing 8.47ms which is huge!

Can anyone explain why? Don't tell me its routers because i'm measuring the between two routers in a path.
Maybe network equipment we can't see? In this trace its within the Vocus network before it heads across the sea and stays within the Vocus network for a good number of hops after so not likely that its bad network design (ie surely all things within their control).

I should add that this is true for Auckland->US etc, and the above trace is not a problem but an example of a generalisation of why Auckland-Sydney (or any other place) seems twice as far away as it should be.

Maybe this is what Kim Dotcom found out: the traffic is being routed via GCSB spying routers - three of them.

Telecom was investigating why his dedicated connection to the Sky Tower suddenly slowed down...and discovered the traffic was being routed to a different place.

Plus some ISPs run through the Internal Affairs spying firewall.....supposedly set up to catch paedophiles (the usual excuse), but mighty handy for spying on absolutely.... everyone.

That would add some latency.

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sbiddle

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#704129 20-Oct-2012 20:40

Linuxluver:
Publius: I'm wondering if some clueful poeple here can help me.

I've been looking at a few traceroutes from NZ to various overseas destinations and what been bugging me is the times involved with the undersea cable legs.

For example round-trip tracing from Auckland to Sydney (host905.rimuhosting.com)
5. vocus1.ape.nzix.net 3.4
6. ten-0-2-0-400.bdr01.akl01.akl.VOCUS.net.au 43.1

So the real-world one-way distance would be 19.85ms
According to wolfram|alpha "distance auckland sydney" is 10.1ms
According to Southern Cross Networks themselves the auckland sydney cable leg is 11.38ms.

So 19.85 real world, 11.38 for the distance. We have a missing 8.47ms which is huge!

Can anyone explain why? Don't tell me its routers because i'm measuring the between two routers in a path.
Maybe network equipment we can't see? In this trace its within the Vocus network before it heads across the sea and stays within the Vocus network for a good number of hops after so not likely that its bad network design (ie surely all things within their control).

I should add that this is true for Auckland->US etc, and the above trace is not a problem but an example of a generalisation of why Auckland-Sydney (or any other place) seems twice as far away as it should be.

Maybe this is what Kim Dotcom found out: the traffic is being routed via GCSB spying routers - three of them.

Telecom was investigating why his dedicated connection to the Sky Tower suddenly slowed down...and discovered the traffic was being routed to a different place.

Plus some ISPs run through the Internal Affairs spying firewall.....supposedly set up to catch paedophiles (the usual excuse), but mighty handy for spying on absolutely.... everyone.

That would add some latency.

While this was quoted in the media I don't for one second actually believe it. You don't intercept traffic by rerouting it, you simply mirror ports. This won't increase latency in any way.

Likewise the DIA filter is simply a BGP based route meaning it also can't affect latency

DonGould

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#704130 20-Oct-2012 20:44

sbiddle: While this was quoted in the media I don't for one second actually believe it. You don't intercept traffic by rerouting it, you simply mirror ports. This won't increase latency in any way.

Likewise the DIA filter is simply a BGP based route meaning it also can't affect latency

Do we really have to let facts get in the way of a good conspiracy story?!

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sbiddle

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#704142 20-Oct-2012 21:01

It's also worth mentioning (as reported in many media stories about Dotcom) that he actually had fibre installed to his home. His fibre isn't going to be running to the Sky Tower, however there were reports he did have a backup wireless link to the Sky Tower.

Linuxluver

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#704159 20-Oct-2012 22:04

sbiddle:

While this was quoted in the media I don't for one second actually believe it. You don't intercept traffic by rerouting it, you simply mirror ports. This won't increase latency in any way.

Likewise the DIA filter is simply a BGP based route meaning it also can't affect latency

Good to know. But you're assuming competence. ;-)

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Linuxluver

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#704161 20-Oct-2012 22:06

DonGould:
sbiddle: While this was quoted in the media I don't for one second actually believe it. You don't intercept traffic by rerouting it, you simply mirror ports. This won't increase latency in any way.

Likewise the DIA filter is simply a BGP based route meaning it also can't affect latency

Do we really have to let facts get in the way of a good conspiracy story?!

The spying isn't a theory. That is a cold, hard fact....whether it's the GCSB watching foreigners or Internal Affairs watching locals.

But the technical assumptions were theoretical...and Steve B has accounted for those.

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Talkiet

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#704171 20-Oct-2012 22:50

Linuxluver:
sbiddle:

While this was quoted in the media I don't for one second actually believe it. You don't intercept traffic by rerouting it, you simply mirror ports. This won't increase latency in any way.

Likewise the DIA filter is simply a BGP based route meaning it also can't affect latency

Good to know. But you're assuming competence. ;-)

He's actually describing how things work. You're the one assuming things. :-)

Cheers- N

Please note all comments are the product of my own brain and don't necessarily represent the position or opinions of my employer, previous employers, colleagues, friends or pets.

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