Comment by BuildTheRobots | Hacker News Reader

Comment by BuildTheRobots | Hacker News Reader

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Coming from the telecoms space, I was slightly amazed to see how little well known SCTP actually is in the networking world.

My old company/offices had site internet provided by one of the top 50 UK Managed Service Providers. They swapped out the on-site router not many years ago as the fibre to site was being upgraded from 100mbit to gigabit and so a new Juniper firewall with GBE ports was required.

Turns out the newer, faster, shinier, though albeit lower model numbered'd Juniper SRX fundamentally didn't support passing SCTP data and suddenly we lost access to all our remote stuff that used it. Ended up on a call with the MSPs Head of Networks (who was not a stupid person), but their opening gambit was "Are you sure you mean SCTP? Oh. What is that then?"

There was also numerous weird kernel bugs with implementations on CentOS 5, 6 and 7 which all would manage to get themselves into weird states where only a reboot would clear - not really what you want from a multi-endpoint, 'copes and recovers well from network weirdness' tunnelling protocol.

> Juniper SRX fundamentally didn't support passing SCTP data and suddenly we lost access to all our remote stuff that used it.

did you file a customer complaint for the device you bought not supporting basic internet protocols? If I look here it mentions "internet" but not TCP or UDP. I'd argue it's false advertising if it actually only supports a percentage of actual internet traffic.

It was one of those situations where the internet was part of the lease, and the property owners got the MSP to provide for multiple companies on the site. Sadly I wasn't a customer of either Juniper or the MSP, and it wasn't something they ever actually claimed to support.

Juniper themselves stated in the manual that this base model device didn't support SCTP, though on ever other level it was faster, more capable and more featureful than the mid-range but much older device it replaced. The MSP didn't have a clue that we (or anyone else for that matter) used SCTP so missed the single footnote mention that the command to enable SCTP forwarding might not be available on some base-level devices.

In their defence, I'm not sure _I'd_ have thought to check if SCTP was supported and I had it running on my network. It works over the internet, it's basically IP, how could it not be suppo---oh.

Funny enough, the first and last time I heard of sctp was in “Unix network programming”. It seemed so promising according to Stevens.

It did see a lot of use. I forgot to say, but the majority of 3G UMTS and 4G LTE radios (operator level and even down to tiny things like femtocells) required it to connect back to the $(core network) and encapsulated a mix of control and user data through it (though often also encapsulating SCTP in a VPN). That is to say, there were a lot of devices out there that used it in anger. If you made a call or used a cellular data session for over a decade, your traffic was likely getting encapsulated through it.

Interesting, thanks! I had no idea. It makes sense that it might be used in specific instances even if it’s not widely used on the internet generally.

Wasn’t it T/TCP that had a large presence in the book?

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