O2_Support_6853
May 12, 2010Nimbostratus
Rate-Shaping bursty traffic
Currently we have an issue in our network with the following architecture:
6 servers ----------> F5 ver 10.1.0 -------------------> Cisco ASA ---------------------->Net B.
All 6 servers need to send 200 messages to clients on the Net B at the exact same time through the F5. The message size is 100 bytes and all will schedule the messages within 1 millisecond. There is no traffic then for around 3 seconds and the same messages must be sent again and so on. Note: The F5 has Gig interfaces and the traffic is sent on already established TCP interfaces.
The calculations are as follows:
200 messages x 100 bytes x 6 servers = 120000bytes in 1 millisecond or 96 Megabits per second.
This is fine however the Cisco ASA device does not appear to have sufficient queue sizes and so tail drops the messages after 50 Megabits per second. We would like to implement Rate Shaping to resolve this issue. My query is if we use sfq on the F5 and set:
Base Rate = 50Mbps
Ceiling Rate= 50Mbps
Burst Size = 0
Will the F5 keep the extra burst in a queue and allow it out of the queue in the 2nd second or will it discard the traffic. The docs are lacking in info on this matter.
(Please Note: TCP rules should allow the dropped messages to be retransmitted but the applicaitions are failing after retransmit, we wish to resolve this without using retransmit).
Thanks in advance.