RSVP Operation Over IP Tunnels
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Auteur(s) :
L. Zhang,
J. Krawczyk,
J. Wroclawski,
A. Terzis
Classé sous :
Internet,
Protocol,
Resource,
Reservation
RFC 2746 RSVP Operation Over IP Tunnels January 2000
........... ............... .............
: _______ : : _____ :
: | | : : | | :
Intranet :--| Rentry|===================|Rexit|___:Intranet
: |_______| : : |_____| :
..........: : Internet : :...........
:..............
|___________________|
Figure 1. An example IP Tunnel
2.2.2. Mapping between End-to-End and Tunnel Sessions
Figure 2 shows a simple topology with a tunnel and a few hosts. The
sending hosts H1 and H3 may be one or multiple IP hops away from
Rentry; the receiving hosts H2 and H4 may also be either one or
multiple IP hops away from Rexit.
H1 H2
: :
: :
+--------+ +---+ +---+ +---+ +-------+
| | | | | | | | | |
H3... | Rentry |===================================| Rexit |..... H4
| | | | | | | | | |
+--------+ +---+ +---+ +---+ +-------+
Figure 2: An example end-to-end path with
a tunnel in the middle.
An RSVP session may be in place between endpoints at hosts H1 and H2.
We refer to this session as the "end-to-end" (E2E for short) or
"original" session, and to its PATH and RESV messages as the end-to-
end messages. One or more RSVP sessions may be in place between
Rentry and Rexit to provide resource reservation over the tunnel. We
refer to these as the tunnel RSVP sessions, and to their PATH and
RESV messages as the tunnel or tunneling messages. A tunnel RSVP
session may exist independently from any end-to-end sessions. For
example through network management interface one may create a RSVP
session over the tunnel to provide QoS support for data flow from H3
to H4, although there is no end-to-end RSVP session between H3 and
H4.
When an end-to-end RSVP session crosses a RSVP-capable tunnel, there
are two cases to consider in designing mechanisms to support an end-
to-end reservation over the tunnel: mapping the E2E session to an
existing tunnel RSVP session (type 2 tunnel), and dynamically
creating a new tunnel RSVP session for each end-to-end session (type
Terzis, et al. Standards Track [Page 5]