[ovs-dev] Clarification regarding Eviction mechanism on basis of Importance.

[Shashwat Srivastava]

Hi Team,

I was going through openflow specs 1.4 and as mentioned in section 
7.3.4.1. page no. 73 "If the flag OFPTMPEF_IMPORTANCE is the only flag 
set, eviction will
be performed strictly in order of importance, that is flow entry with 
lower importance will always be evicted before flow entry with higher 
importance.", I have some queries regarding eviction behaviour.

Considering the case when Eviction is enabled on the basis of IMPORTANCE 
(i.e. flows of lower importance will be evicted) and the table limit is 
set to 5. Now suppose there are 5 flows of importance 100,101,102,103,104.
Now when the new flow is entered and has IMPORTANCE=10 and as the eviction 
is enabled, the switch will evict flow having IMPORTANCE=100.
Now is'nt this illogical to evict flow of higher importance (in this case 
importance=100) for the new flow of lower importance (in this case 
importance=10).

Considering the users above importance=50 as PLATINUM user and user with 
importance < 50 as normal user. So for a normal user a platinum user's 
service will be disrupted and will suffer loss of packet (although for 
short period of time).

Kindly explain this behaviour of openvswitch ?

Regards
Shashwat Srivastava
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