IPv6 Address Assignment and Route Selection for EndtoEnd Multihoming

1
IPv6 Address Assignment and Route Selection
for End-to-End Multihoming
draft-ohira-assign-select-e2e-multihome-01.txt

• Kenji Ohira
• Kyoto University

2
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.

3
Hierarchical address assignment(assumption)

• 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.

2-level hierarchical model
4
Source address based path selection

• Selection of a pair of src/dst address
  immediately gives a path.
• The number of candidate paths is the same as the
  number of src/dst pairs.
• An end application can select a path without
  full-route information.
• This enables
• Redundancy
• Speedy path alternation initiated by end
  host/applications.
• Independent of L3 routing protocols.
• Load sharing
• Each end-to-end flow can use multipaths.

src MAs, dst MBt
src LAs, dst MBt
5
Implementation of site-exit router selection (1/2)
to ISP L
to ISP M

• Source address based routing 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
• Host/application based policy decision
• (see draft-ohta-e2e-multihoming)

site exit router
LAhost
MAhost
site A
6
Implementation of site-exit router selection (2/2)
to ISP L
to ISP M

• To reduce the impacts on routing 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.
• Routing loop never occurs.
• Modification to hosts, routers and routing
  protocol is needed but is minimum.

site exit router
LAhost
MAhost
site A
7
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)

8
Routing Model
src MAs, dst MBt
src LAs, dst NBt
src MAs, dst NBt
src LAs, dst MBt