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Task #1676

closed

Allow strategies to send the same Interest via the same outgoing face before the previous out-record expires

Added by Alex Afanasyev almost 10 years ago. Updated almost 8 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Category:
Forwarding
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% Done:

0%

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Description

It is desirable for some strategies to do retransmission of Interests before the existing out-record expires.

One example of this is a strategy with "retransmission detection" (or may be it should be a separate module), which considers the seconds Interest with a different nonce received from the same face as re-expressed by the client (e.g., client detected a loss using equivalent of triple duplicate ACK in TCP), and retransmits this Interest even if there are existing out-record(s).

Actions #1

Updated by Junxiao Shi almost 10 years ago

  • Assignee set to Junxiao Shi

I can confirm that this restriction is not enforced in outgoing Interest pipeline.

However, pit::Entry::canForwardTo returns false if an unexpired out-record exists, informing the strategy that the upstream is not eligible.
We should change this method, but the change shall be careful not to break existing strategies.

Actions #2

Updated by Junxiao Shi over 9 years ago

  • Description updated (diff)

Question: if strategy decides to forward a similar Interest to an outFace with unexpired out-record, is the Nonce required to be different from the previous one recorded in the out-record?

My opinion is YES, because using a duplicate Nonce causes the Interest to be dropped at the nexthop (unless it's lost at this particular link).
If the consumer retransmits, we already have a new Nonce to use.

Actions #3

Updated by Alex Afanasyev over 9 years ago

Nonce should be different. This particular issue is more about consumer retransmission detection (nonce here is by definition different), rather strategy-decided retransmission. But in any case, there is no point of sending the Interest that can be considered duplicate.

Actions #4

Updated by Junxiao Shi over 9 years ago

It's inaccurate to say "Nonce of consumer retransmission is by definition different", because there isn't a definition for consumer retransmission yet.

In CCNx 0.7.2, when same Nonce arrives from the same face, it's treated as consumer retransmission and not a duplicate.

Actions #5

Updated by Davide Pesavento over 8 years ago

  • Target version changed from v0.3 to v0.5
Actions #6

Updated by Junxiao Shi almost 8 years ago

  • Status changed from New to Closed

As indicated in note-1, outgoing Interest pipeline allows a strategy to send Interest before out-record expires.

pit::Entry::canForwardTo has been renamed as fw::canForwardToLegacy in #3545 and it's not recommended for new strategies.

The restriction indicated in this issue description no longer exists, and this issue can be closed.

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