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Mia_254836's avatar
Mia_254836
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May 03, 2016

About reusing the IP and ports deleted in the connection table

Hi Experts,

 

The BIG-IP will delete the connection by connection idle timeout or RST from the client or the server. Thus, after BIG-IP delete the relevant connection in the connection table. I wan wondering whether the BIG-IP use immediately the IP and port deleted in the connection table.

 

For example,

 

  1. BIG-IP establish a connection with 1.1.1.1:10000 -> 2.2.2.2:80
  2. After idle timeout, BIG-IP delete the above connection.
  3. If the new SYN with the source(1.1.1.1:10000) and the destination(2.2.2.2:80) is arrived immediately to the BIG-IP, I was wondering whether the BIG-IP create a connection(1.1.1.1:10000 -> 2.2.2.2:80) and establish or not.

Thank you. Mia

 

2 Replies

  • F5 developers can answer precisely but I can tell you from personal experience that 3 in your example does not happen. The IP:port on source can't be reused until twice the maximum segment lifetime -- even then it appears F5 cycles through least recently used ephemerals per source IP first.
  • If the connection is not in our connection table, then yes we will initiate a new connection when receiving a SYN.