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Topology-Insensitive Service Traversal

Document Charter Topology-Insensitive Service Traversal WG (tist)
Title Topology-Insensitive Service Traversal
Last updated 2003-12-10
State Approved
WG State Concluded
IESG Responsible AD (None)
Charter edit AD (None)
Send notices to (None)


The notion of using RSVP or an in-band signaling protocol
for finding firewalls and NATs has been floating around for
years but hasn't received detailed scrutiny. At the same
time, work on using out-of-band signaling (midcom) has found
that it is highly sensitive to topological complexity.
Midcom additionally leaves the problem of locating
middleboxes in the network unaddressed.

By using a protocol like RSVP, we can simultaneously address
the problems of locating middleboxes in the network, routing
requests to the correct middlebox, and handling topological
complexity (for example, if there are both firewalls and
NATs in a datapath it may be extremely difficult to
determine the correct address to use in a firewall pinhole
request). We can solve these problems by leveraging
existing IP routing mechanisms and sending middlebox
communications request along the normal forwarding path, but
it introduces other problems (security, correct function
with 3rd-party call control and signaling).

This BOF is a first step towards examining whether and under
what conditions an inband middlebox communication protocol
would be useful in practice. Among the topics to be
discussed are the relationship to other work, such as NSIS
and TED, whether or not this approach really would provide
greater network transparency, and interactions with
applications that use 3rd-party signaling.