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 Steps1. 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 RAPerform following checks one after another until a

decision is made:1. If DNAHostPrefixList and Prefix List in RA overlap

• No link change2. If RA is Complete

• Link change3. 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’• Link Change

5. Wait for NumRSRAComplete RA messages to complete.

6. If no overlapping prefixes found• Link Change

7. If overlapping prefixes found• No link change

Open Issues1. 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 delay2. 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.

• ???