Forum Discussion
Militza
Nimbostratus
NimbostratusUnable to download 15 MB excel file through LTM.
We have configured HTTP application with port 80 on F5 LTM. We trying to download excel file using that application downloading gets failed after few minutes.
No logs found in var/ltm realated to download failed.
Hi Militza ,
Do you see in Packet captures >>> ( TCP Window Full & TCP zero window ) while downloading this file ?
>Btw , Try to remove the HTTP Profile and use ( Performance layer 4 ) and Test.
>Are there any firewalls between F5 Bigip and Servers or between F5 Bigip and Client ).> Maybe adjusting window scalling solve your issue , but first tell us if you see ( TCP Window Full & TCP zero window ) flags or not in your captures ?
Hello,
Can you please provide any additional information? for example: virtual server configuration (virtual server type and profiles assigned) also, is the service working fine and only downloading files is failing?
what is the software version you are running? you can check for any BUG that you might be facing, for example:
https://cdn.f5.com/product/bugtracker/ID966785.html
Also, you can start generating a tcpdump and check the output, it will be clear as the service port is 80, you can use the below command to check out what is actually happennig on both client and server side.
#tcpdump -nnnveti 0.0:nnnp host 51.39.227.242 and port 80 -s0 -S -w /var/log/filename.pcap
replace the above IP with the client's IP, then open it in wireshark.
Thanks,
- whisperer
MVP
You will have to provide more information than that for any assistance here 🙂 Have you performed a tcpdump on client and server side? Have you tried to download the file via curl from thr F5? Can you share your virtual server config from bigip.conf?
MilitzaYes performed TCPDUMP and found mutliple tcp retransmited in between F5 and server.
Application is working fine only issue with download file and able to downlad file if access application without F5.
ltm virtual file_download_80 {
creation-time 2022-12-23:12:05:06
destination 10.100.10.11:http
ip-protocol tcp
last-modified-time 2022-12-23:13:33:21
mask 255.255.255.255
persist {
file_download.app/file_cookie-persistence {
default yes
}
}
pool file_download_pool_80
profiles {
file_download.app/file_download_http { }
tcp { }
}
serverssl-use-sni disabled
source 0.0.0.0/0
source-address-translation {
type automap
}
translate-address enabled
translate-port enabled
vs-index 63
}- whisperer
Can you also provide the config for the file_download.app/file_download_http object? Usually issues like these result from the HTTP profile.... can you try to remove this profile and re-attempt download to test?
- Militza
ltm profile http file_download.app/file_download_http {
app-service /Common/file_download.app/file_download_http
defaults-from http
insert-xforwarded-for enabled
redirect-rewrite none
}
- whisperer
Nothing obvious here that could be causing your issues. Although, the multiple re-transmits is a bit telling. Not sure if this is a new setup, or an older F5 BIG-IP installation. Did you also check the speed/duplex negotiation on the swithports and if you see any drops or issues there?
Hi Militza ,
Do you see in Packet captures >>> ( TCP Window Full & TCP zero window ) while downloading this file ?
>Btw , Try to remove the HTTP Profile and use ( Performance layer 4 ) and Test.
>Are there any firewalls between F5 Bigip and Servers or between F5 Bigip and Client ).> Maybe adjusting window scalling solve your issue , but first tell us if you see ( TCP Window Full & TCP zero window ) flags or not in your captures ?
- Militza
I changed the virtual server type form standard to performance layer 4 and its started working.
Thanks for all input.
