Forum Discussion
Sean_Nguyen_121
Nimbostratus
NimbostratusCofigure tcp profile for Delay Ack value similar to rto_min settings
Hi,
I am using tcp-cell-optimized profile for my virtual server. My devices are 2G & 3G devices on a very slow network. The device ran on Linux system and have rto_min set to 6.5 sec. When these device connect to my virtual server, I can see the average tcp retransmistion time is around 1.2 sec. Is there a way to increase the retransmission time on my virtual server to be around like 3 sec average? I have delay-ack enable but I can't find any configuration to set the initial delay-ack time for configuration.
Thanks,
Sean Nguyen
4 Replies
marco_octavian_From what I know, you can't modify the delayed-ack parameters. Wouldn't you even know how to intelligently modify this if you could???
Modifying the rto_min is done at the route level on linux and you can do the same on the LTM (linux/tmos) but I would experiment to see what the results really are. Example:
[root@ltm1:Active:Disconnected] config ip route change default dev internal rto_min 60ms
[root@ltm1:Active:Disconnected] config ip route show table main
127.1.1.0/24 dev tmm0 proto kernel scope link src 127.1.1.1
127.3.0.0/24 dev mgmt_bp scope link
192.168.5.0/24 dev eth0 proto kernel scope link src 192.168.5.115
172.16.21.0/24 dev internal proto kernel scope link src 172.16.21.8
172.16.31.0/24 dev external proto kernel scope link src 172.16.31.8
1.1.1.0/24 dev HA proto kernel scope link src 1.1.1.1
default dev internal scope link rto_min lock 60ms
default via 192.168.5.5 dev eth0 metric 9
[root@ltm1:Active:Disconnected] config
You could also put in a "functional" iRule just to issue a pause/wait with the "after" commmand for each VS.
Having said all this, I would not change anything. Is it causing any issues right now ?It seems odd to inject delay, cell network or otherwise. Why do you want this long delay? How does this streamline your app performance?
Sean_Nguyen_121When I look at the package capture, it seems to me that if the ACK is delayed like in 3 sec, we would cut the retransmission rate dramatically. Because we pay for the data, it is critical to us to optimize retransmission as much as we can.
Sorry that I am not very familiar with F5 setup, but you suggest to apply the rto_min on the virtual server box?- marco_octavian_That actually makes sense.
I'm not suggesting to make any changes. I'm just giving you the basic commands/concepts to do so if you prefer. I'm not real comfortable changing any of this but it looks like you have possible justification in this scenario. - nitass
Employee
what version are you running? if it is 11.0.0+, have you tried syn-rto-base (initial retransmission timeout base multiplier for syn retransmission) in tcp profile? does it help?
sol7559: Overview of the TCP profile
http://support.f5.com/kb/en-us/solutions/public/7000/500/sol7559.html
