An%20extension%20to%20ADD-IP%20draft%20to%20send%20cumulative%20ASCONF%20chunks%20draft-marushin-sctp-asconfext-01.txt

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An extension to ADD-IP draft to send
cumulativeASCONF chunksdraft-marushin-sctp-asco
nfext-01.txt

• Shin Maruyama (Kyoto Univ., JAPAN)
• Masahiro Kozuka (Kyoto Univ., JAPAN)

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Limitation on ASCONF transmission

• Sending new ASCONF chunk is prohibitedif
  outstanding ASCONF chunk exists.
• No modification on queued ASCONFs

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A typical scenario to break an association

• Node A supports IPv4 and IPv6 address
• Node B supports only IPv4
• Node A first loses IPv4 address and then get
  another IPv4 address.

Node A
Node B
IPv4 IPv6
IPv4
1.
Node A loses IPv4 address
Node A only has IPv6 address, ASCONF cannot be
sent out
ASCONF DEL-IP(IPv4)
2.
Once this happens, following ASCONFs are also
blocked
ASCONF ADD-IP(IPv4)
3.
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Another Typical Scenario

• Node has a single interface and an IP address,
  and the interface goes down.
• The node get another address, but the address is
  disconnected.

Node loses IP1
1.
IP1
ASCONF
Get unreachable address IP2, ASCONF-ACK never
returned
IP1IP2
2.
ASCONF-ACK
3.
Get another reachable address IP3, but ASCONF
cannot be sent out
ASCONF ADD-IP(IP3)
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Cumulative ASCONF chunks

• On sending ASCONF chunks, if there are any
  outstanding ASCONFs, bind them up!

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Some Remarks

• On bundling ASCONFs, all the outstanding ASCONFs
  must be bundled in order.
• ASCONF_ACK must be returned to the source address
  of bundled ASCONFs
• Receiver must return ASCONF_ACKs for all ASCONFS
  bundled even when some of themhave already
  processed.
• ASCONF_ACK should be cached until the sender is
  assumed to have received it.
• ASCONF_ACK should also be bundled.

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Questions?
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