Apologies upfront for my not being able to successfully google this on my own...
Is there an RFC or other standard that specifies that IPv4 connected
devices must support the concepts of Subnet Mask and Default Gateway?
I have a kludgy (<- technical term) vendor that has developed a custom
AP that only has an IP address. Whilst cleaning up our network and
turning off proxy-arp, lo and behold, it isn't really all that
functional anymore.
Thanks in advance, replies off-list welcome.
- Scott
Is there an RFC or other standard that specifies that IPv4 connected
devices must support the concepts of Subnet Mask and Default Gateway?
No, because there's plenty of applications (embedded systems, for example),
where you have no need or desire to be able to talk to things off-local-net.
I have a kludgy (<- technical term) vendor that has developed a custom
AP that only has an IP address.
Be afraid. Be very afraid. Any vendor in *this* year who makes gear that
is supposed to connect edge devices to the rest of the net but doesn't
get the ideas of subnet masks and default gateways should be feared.
I'd subject that thing's stack to some stress analysis - if they didn't get
THAT, who knows what ELSE is evil/broken in the stack?
> Is there an RFC or other standard that specifies that IPv4 connected
> devices must support the concepts of Subnet Mask and Default Gateway?No, because there's plenty of applications (embedded systems, for example),
where you have no need or desire to be able to talk to things off-local-net.
Which doesn't really excuse you from subnet mask, I wouldn't think.
You clearly don't need a default gateway if you're not going to reply
to off-net packets, but how would you idenfity broadcast packets if you
didn't know the netmask?
> I have a kludgy (<- technical term) vendor that has developed a custom
> AP that only has an IP address.Be afraid. Be very afraid. Any vendor in *this* year who makes gear that
is supposed to connect edge devices to the rest of the net but doesn't
get the ideas of subnet masks and default gateways should be feared.
Indeed, run far, far away.
And yes, Scott: RFC 791. It's not just a good idea...
Cheers,
-- jra
> > Is there an RFC or other standard that specifies that IPv4 connected
> > devices must support the concepts of Subnet Mask and Default Gateway?
>
> No, because there's plenty of applications (embedded systems, for example),
> where you have no need or desire to be able to talk to things off-local-net.Which doesn't really excuse you from subnet mask, I wouldn't think.
You clearly don't need a default gateway if you're not going to reply
to off-net packets, but how would you idenfity broadcast packets if you
didn't know the netmask?
all bits set in the dst mac is one way.. not sure how you send them tho if you
dont know the dstIP to put into the packet
Steve
Thanks to all who replied, actually 791 doesn't specify that a host
needs to implement these things; it lays out IP and how to use a
network mask / gateway.
RFC1122 (thanks to you off-listers) section 3.3.1.6 specifically
(using the RFC's famed "MUST" verbiage) states that a host use a
configurable subnet mask and default gateway.
Oh believe me, if I had a choice, we would have not put this stuff in.
It's here already and we're just trying to work around it. More
specifically tell the vendor to get their act together and be a good
network citizen.
Thanks all!
- Scott