Routing without source information and Traffic self-similarity
boydn at jacana.lcs.mit.edu
Thu Sep 18 21:03:26 UTC 1997
> Okay... I'll bite...
> Maybe I am just naive but if the IP header did not contain a source
> address, how would TCP acknowledgement, windowing, or re-transmission take
> How would a request for data be serviced? Would responses always be in
> the form of a all-nets/all-hosts broadcast? How else would the response
> get back to the originating host?
The point is that the source address is not explicitly *required* in the
*header*. Thus, a source and destination could "setup" an IP session by
negotiating a "session ID" or something - the first packet from source to
destination would include the source's address in the *payload* along with
information to start the negotiation process. I am describing, in other words,
something like an ATM transport layer that would live below IP.
> Routing Protocols.... we need source addressing so we know, at the IP
> layer, who our sources of information are, and then, who can we accept
> information from and who we should refuse information from. In addition,
> access-lists, route-filters, and other types of security would be
> non-functional without source addresses.
Now you're addressing (so to speak ;) the kind of issues that I am concerned
with: without mandating source information in the header, how can the
destination make decisions about rejecting/accepting traffic? alternatively,
how can middle agents (e.g., routers) do filtering, etc.? how can we
possibly prevent spoofing?
> Lastly, how would you accomplish a traceroute on a network with no source
> addressing? Where would the ICMP ttl expired messages be directed if
> there was no source address in the packet?
I don't know! You tell me! Do we make each intermediate router "aware" of
the negotiated session ID? Doesn't sound tractable to me.
I hope this clarifies this - I don't think it is so strivial as my initial
email led you to believe.
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