Bug #3889
open
Retransmission suppression is too aggressive
0%
Description
The retransmission suppression logic defined in #2377 is supposed to prevent Interest flooding by consumers, caused by either malicious intent or misconfiguration.
However, there is only one bug report mentioning too little suppression of Interests (#3230) and at least four reports reporting too much suppression (#1871, #1913, #1966, #2062)!
This suggests to me that the current retx suppression mechanism is generally too aggressive and should be re-designed.
One specific suggestion I have: Only suppress Interests received from a new incoming face (one that doesn't already exist in the PIT). This allows to aggregate Interests from different consumers without propagating all of them (thus fixes bug #3230), but also propagates Interests coming from the same face, which are most often re-transmissions from the same consumer.
This allows a single consumer to retransmit an Interest as fast as it wants, a potential DoS attack. However, the same consumer can easily start a similar attack by just sending out Interest with a new name, either on the same or on a different prefix. Thus, the retransmission suppression provides no significant protection against intentional DoS attacks.
There may be cases when Interests from the same consumer come in on two different faces (e.g. a consumer sending sequentially on LTE and WiFi). We can discuss a design how to detect and handle these cases below.
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