Opened 10 years ago

Closed 10 years ago

#244 closed other technical (fixed)

max-age vs. network latency and retransmissions

Reported by: cabo@… Owned by: draft-ietf-core-coap@…
Priority: minor Milestone: post-WGLC-1
Component: coap Version: coap-09
Severity: In WG Last Call Keywords:


Cullen Jennings notes (msg03072ai):

Section 5.7

Last paragraph of section 5.7. I'm worried about slowly extending the life time of the cache by each step not taking into account the network latency. So if there is 2 condos of latency on the mesh network and device A passed something with a Max-Life to 10 seances to Cache B that later caches to cache B, it could end up living for multiple seconds longer than it should have.

Also, Klaus Hartke notes (nits9c):

Retransmission of a response can significantly extend the
time the response takes to arrive at the client. Should the
Max-Age of the response be reduced with each retransmission?
(See also [msg03072ai])

The somewhat lame text that has been added to the working version of coap-12 is:

Considering potential network delays on the way from the
origin server,
a proxy SHOULD be conservative in the max-age values offered.

However, we could also add text that recommends (or requires?) proxies to update max-age in their retransmissions. We could also extend this recommendation/requirement to origin servers.

Carsten's view:
In many cases, this is a quality of implementation issue.
But it does not hurt to point out the issue.
So I added text in the definition of the option Max-Age that indicates that the value of Max-Age is current at the time of transmission.

Change History (1)

comment:1 Changed 10 years ago by zach@…

  • Resolution set to fixed
  • Status changed from new to closed
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