Quite often we seen comments like "protocols above Layer4 in the OSI model are off-topic": (emphasis mine)

DHCP Off-topic

Question: Are there any OSI layer4 (or above) network protocol questions which are on-topic?

1 Answer 1


What is On-Topic

Are there any OSI layer4 (or above) network protocol questions which are on-topic?

Yes, this is even hinted at in the help center:

design of protocols used to operate a network

If the question is about the design, theory or even simply using features of protocols used to operate a network, then the question should be on-topic. Protocols used to operate a network include (but are not limited to): ARP, RIP, OSPF, BGP, ISIS, SNMP, DHCP, RADIUS, TACACS+, NTP, YANG, NETCONF and DNS. Some of the aforementioned protocols are certainly above OSI Layer4

Potentially confusing guidance

What's confusing is that there is some conflicting guidance on this subject in the help center:

Questions above OSI Layer4 off-topic

Using this logic one could potentially argue that questions about the BGP protocol itself are off-topic; the BGP protocol sits squarely above TCP (i.e. above OSI Layer4) in the protocol stack. However, that was not what we intended when we wrote the help center.

Why is this so confusing?

We are part of the Stack Exchange network. There's this tiny site in the Stack Exchange network called StackOverflow where people often ask questions about code for network applications; as part of the Stack Exchange network, we get a significant amount of drive-by traffic from StackOverflow coders. If we did not draw a hard line about protocols being supported, we could wind up fielding an endless march of questions about why someone's application broke over the network (or even the design / operation of their own custom network protocol).

Nevertheless, this distinction should never be used as a reason to close a question about the operation of someone's network, as long as they're using a supported network infrastructure protocol (i.e., it's not a network infrastructure protocol they made up on their own).

People use http to manage firewalls; does this mean http qualifies as a network infrastructure protocol?

http is not a network infrastructure protocol in any significant way; it's primary use is for people to write portable GUIs for their applications. The fact that we happen to use http to manage a firewall is simply because we need transport for a remote GUI / restful API.

What can we do to improve this situation?

I believe we should modify the help center to be more explicit about the supported protocols above OSI Layer4.

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