Internet Routes "Maxing Out"

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Zeon

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#151116 14-Aug-2014 12:37

Hey guys,
Saw this come up on the NZNOG (NZNOG is a group of all the network operators e.g. ISPs in the country) - it looks like the number of "routes" on the internet is close to overloading some older routers. There's a good explanation here but to explain it briefly, the internet is made up of "routes" which tell you how to reach different IP addresses. Your computer or network will have an IP address and the service you connect to like Facebook will have another. The routes tell your computer how to reach Facebook. The number of routes is expanding, older Cisco routers have a maximum of 512,000 supported routes but the number has already reached 500,000 and for a brief period went over 512,000 causing parts of the internet to "go dark" from others.

it will be interesting to see those who are running older systems and not proactively monitoring them drop offline as their limits are hit.

http://www.bgpmon.net/what-caused-todays-internet-hiccup/

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#1108606 14-Aug-2014 18:36

Interesting, bet there are a lot of providers sitting too long on old gear.

alexx

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#1108640 14-Aug-2014 20:29

More here:
http://arstechnica.com/security/2014/08/internet-routers-hitting-512k-limit-some-become-unreliable/

Some older routers kept their routing tables in "a type of memory known as ternary content-addressable memory, or TCAM. Unlike typical RAM, content-addressable memory allows software to provide content and to recall the address of the memory. Such operations are much faster using binary CAM than RAM."

It seems that in some cases, the routing tables reached the 512K limit of many of those older routers.

#include <standard.disclaimer>

freitasm

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#1108642 14-Aug-2014 20:32

Expect the mainstream media to hit with headlines that are as good as something out of Buzzfeed. From the Herald (syndicated):

"Fears internet is running out of space as eBay crashes"

muppet

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#1108659 14-Aug-2014 20:37

This has been known about for at least a few months (well, a lot longer, but discussed in earnest for a few months)

The sky isn't falling, it's just people who haven't planned being affected.

muppet

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#1108663 14-Aug-2014 20:43

Zeon: The number of routes is expanding, older Cisco routers have a maximum of 512,000 supported routes but the number has already reached 500,000 and for a brief period went over 512,000 causing parts of the internet to "go dark" from others.

That's not quite true. Older Cisco routers by default partition their routing table to support 512k IPv4 routes. It's possible to support more, at the expense of other (IPv6, L2 MAC) address entries. The problem is that to reconfigure the router's TCAM (It's forwarding table memory), a reboot is required. If you' had a router up for 2 years, you're understandable nervous about rebooting it, especially because of this issue.

Inphinity

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#1108666 14-Aug-2014 20:58

muppet:
Zeon: The number of routes is expanding, older Cisco routers have a maximum of 512,000 supported routes but the number has already reached 500,000 and for a brief period went over 512,000 causing parts of the internet to "go dark" from others.

That's not quite true. Older Cisco routers by default partition their routing table to support 512k IPv4 routes. It's possible to support more, at the expense of other (IPv6, L2 MAC) address entries. The problem is that to reconfigure the router's TCAM (It's forwarding table memory), a reboot is required. If you' had a router up for 2 years, you're understandable nervous about rebooting it, especially because of this issue.

That's where redundancy and alternate routes comes in, though... surely no major network provider is relying on a single router for any major operations these days?

muppet

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#1108669 14-Aug-2014 21:09

Inphinity:
That's where redundancy and alternate routes comes in, though... surely no major network provider is relying on a single router for any major operations these days?

It's not a redundancy issue. It's the fact that if your routers receive over 512k routes, they'll black-hole the routes they couldn't accept. It doesn't matter if they have 1 router or 16, if they're all the same router and they all receive routing updates from their upstream that push them over their limit, they'll be affected.

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Inphinity

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#1108671 14-Aug-2014 21:11

muppet:
Inphinity:
That's where redundancy and alternate routes comes in, though... surely no major network provider is relying on a single router for any major operations these days?

It's not a redundancy issue. It's the fact that if your routers receive over 512k routes, they'll black-hole the routes they couldn't accept. It doesn't matter if they have 1 router or 16, if they're all the same router and they all receive routing updates from their upstream that push them over their limit, they'll be affected.

No, but I meant in relation to the 'risk' of a reboot.

muppet

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#1108675 14-Aug-2014 21:17

Inphinity:
No, but I meant in relation to the 'risk' of a reboot.

Oh right - then yes, I agree with you. A reboot shouldn't be a (big) deal. I guess it's more that "If it ain't broke, don't fix it" thing. Though now it actually is broke.

Behodar

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#1108686 14-Aug-2014 21:28

It shouldn't be too hard to drain it...

gjm

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#1108791 15-Aug-2014 08:20

I hope someone consulted the elders of the internet and asked them to add more jigaflops to the cloud some I can keep watching my cat videos on youtube

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#1108804 15-Aug-2014 08:52

Oh, dear. IT Crowd video required at this moment:

I guess if mainstream media non-tech journalists watching this wouldn't get the joke anyway.

macuser

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#1108848 15-Aug-2014 09:56

The internet needs to cut down on bytes, it's gaining in size quickly!!

PhantomNVD

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#1110093 17-Aug-2014 20:15

But more importantly for a 1-cable country like ours... apparently SHARKS are attacking the internet too!!!

http://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=11309925

investigative scare tactics at it's best (note the 2005 date on the video) aren't we so lucky that it hasn't happened here in the last 10 years since that video was taken? (!)

insane

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#1110108 17-Aug-2014 20:51

PhantomNVD: But more importantly for a 1-cable country like ours... apparently SHARKS are attacking the internet too!!!

http://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=11309925

investigative scare tactics at it's best (note the 2005 date on the video) aren't we so lucky that it hasn't happened here in the last 10 years since that video was taken? (!)

The SX cable has two rings, will take at least two hungry sharks attacking unshielded sections to cause serious concern.

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