Download IPv6 Address Assignment and Route Selection for End-to-End

IPv6 Address Assignment
and Route Selection
for End-to-End Multihoming
draft-ohira-assign-select-e2e-multihome-01.txt
Kenji Ohira
Kyoto University
IETF #57 in Viena
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Overview of our draft
• Goal:
– Not an end host but each end application can decide a
route. (End-to-end multihoming)
• Our proposal:
– A multi-level hierarchical network model and address
assignment.
– A route is determined by selecting a pair of a source
address and a destination address.
– Selection is done on layer 4 or above, not on layer 3.
IETF #57 in Viena
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Hierarchical address assignment
(assumption)
Local ISP L Local ISP M
L::
M::
• Each ISP assign an
address prefix to a site
hierarchically.
• Our draft shows that this
model can be extended to
3 or more level model.
L:A:: M:A::
Site A
2-level hierarchical model
IETF #57 in Viena
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Source address based path
L::
M::
N:: selection
• Selection of a pair of src/dst
address immediately gives a path.
L:A:s s
M:A:s
– The number of candidate paths is the
same as the number of src/dst pairs.
M:B:t
N:B:t
t
src: M:A:s, dst: M:B:t • An end application can select a
path without full-route information.
• This enables:
L::
M::
N::
– Redundancy
• Speedy path alternation initiated by
end host/applications.
• Independent of L3 routing protocols.
L:A:s s
M:A:s
t
M:B:t
N:B:t
src: L:A:s, dst: M:B:t
– Load sharing
• Each end-to-end flow can use
multipaths.
IETF #57 in Viena
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Implementation of site-exit router
selection (1/2)
to
ISP L
site exit
router
to • Source address based routing
ISP M is employed in a site
• Site-exit router selection is
done by selecting a source
address
(see draft-huitema-multi6-hosts)
• Such a selection is done on L4
or above
L:A:host
site A
M:A:host
– Host/application based policy
decision
(see draft-ohta-e2e-multihoming)
IETF #57 in Viena
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Implementation of site-exit router
selection (2/2)
to
ISP L
site exit
router
to To reduce the impacts on routing
ISP M mechanisms, we propose:
• Announce default routes to
site-exit routers and intra-site
routes only.
– Full route is not needed
• Apply source address based
routing only for default route
entries.
L:A:host
site A
M:A:host
– Routing loop never occurs.
– Modification to hosts, routers
and routing protocol is needed
but is minimum.
IETF #57 in Viena
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Concluding Remarks
• Site-exit router selection using source address based
routing
– for end-to-end redundancy/load sharing with multiple paths
• Impacts on hosts, routers and routing protocols
– Intra-site source address based routing is needed, but special
treatment only for default routes is enough.
• Impacts on L4 or above
– Some mechanism is needed for proper source address
selection
– Transport layer survivability would be supported by
• Socket API extension with LIN6 (draft-arifumi-lin6-multihome-api)
• Some extension of SCTP multihoming support (RFC3257)
IETF #57 in Viena
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