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Detecting Network Attachment in IPv6
Networks (DNAv6)
draft-ietf-dna-protocol-05.txt
S. Narayanan, Ed.
J. Kempf, E. Nordmark, B.
Pentland, JH. Choi, G. Daley,
N. Montavont, N. Moore.
Outline
• Overview of DNA
• Open Issues
• Next Steps
Link Identification
• The set of prefixes configured to
be advertised on the routers of the
link.
– The Complete Set
– The smallest prefix could be used to
represent the set on the router side
– A selected (Landmark) prefix could be
used to represent the set on the host
side
Router Operation
• Routers listen to advertisement from
other routers and create
– DNARouterLearnedPrefixList
• Send CompleteRA messages
• Respond to Landmark questions
– DNARouterList
• Order RA messages based on the link-local
address
• Include smallest prefix in all RA
messages except Landmark responses
Fast RA
• Generate a token based on the link-local
address of the routers on the link
• A host token is generated using the
source address of the RS message
• Ranking is decided based on the XOR of
the host token and the router tokens
• FastRAThreshold controls the number of
fast RA messages
• Token bucket for rate limiting
DNA Host Steps
1. Mark all the IPv6 addresses in use as optimistic.
2. Set all Neighbor Cache entries for routers on its
Default Router List to STALE.
3. Send router solicitation. (See Section 5.2.5).
4. Receive router advertisement (s).
5. Mark that router's Neighbor Cache Entry [3] as
REACHABLE, or add a Neighbor Cache Entry in the
REACHABLE state if one does not currently exist.
6. Process received router advertisement. (See Section
5.2.6).
7. If the link has changed Change the IP configuration
parameters of the host (see Section 5.2.7).
8. If the link has NOT changed Restore the address
configuration state of all the IPv6 addresses known
to be on the link.
9. Update default routers list and their reachability
information (see Section 5.2.6.3).
DNA Host: Processing RA
Perform following checks one after another until a
decision is made:
1. If DNAHostPrefixList and Prefix List in RA overlap
•
No link change
•
Link change
2. If RA is Complete
3.
•
If RA is a DNA RA
If a DNA RA was received before the link-up event “Link
Change” has occurred.
4. If DNAHostPrefixList is ‘Complete’
5.
6.
7.
•
•
•
Link Change
Wait for NumRSRAComplete RA messages to
complete.
If no overlapping prefixes found
Link Change
If overlapping prefixes found
No link change
Open Issues
1.
Flash renumbering
• Three possible levels:
1. do nothing special for flash renumbering and
immediate reassignment (other than telling
network admin to not immediately reassign
prefixes)
2. do something so that a host can recover, but it
might take a while (e.g., 90 minutes)
3. handle it without any delay
2. Do we need all of the router configuration variables?
• UnicastRAInterval
• MaxUnicastRABurst
• RASeparation
• MulticastRADelay
• FastRAThreshold
Open Issues (Contd.)
3. All other open issues are about
readability/clarity.
Next steps
• Need volunteers to send modified
text for some sections.
– 5.1.7 (Smallest prefixes)
– 5.3 (Tentative Options)
– ???
• Need volunteers to review the
document
• We would like to last-call around end
of April.
• ???