Server Fault is a question and answer site for system and network administrators. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I recently noticed that my ISP doesn't like routing native SCTP traffic over the Internet, unless it's tunnelled through UDP. A bit of a pain, but I solved the issue by using tunelling.

This issue got me thinking - other than TCP and UDP, which transport layer protocols are (generally) allowed to be routed properly across the Internet, over IPv4? Is the "normal" policy to allow all forms of IPv4 traffic, regardless of the protocol?

share|improve this question
up vote 3 down vote accepted

All IP packets should be routed by your ISP, independent of the higher-layer protocol. Of course this will become very difficult with IPv4 packets when they have to use NAT444/CGN/LSN/DS-Lite/A+P/etc when IPv4 addresses run out (depending on where you are this might already have happened).

But then they should still route all IPv6 packets...

share|improve this answer
Does this include IPv4 packets whose protocol number is set to an undefined protocol number? e.g. 0xFE – Polynomial Mar 6 '12 at 17:13
Yes, it should. The nice thing about the internet is that end-points can develop/experiment/etc new protocols without the core network needing to know about them. The core just looks at source and destination addresses and doesn't care about the rest. At least, as long as your internet provider doesn't try to be 'smart'... – Sander Steffann Mar 6 '12 at 17:24

Generally IPv4 network should route any ip packets regardless of upper-level protocols like tcp and udp. IP packet contains all necessary data for routing (src and dst addresses in IPv4 network and other required data).

I guess limitations of transport protocols in IPv4 network is an absurd.

share|improve this answer

You got absolutely loads of transport layer protocols that 'normally' can be routed over the Internet. See

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.