Forum Discussion

Nimbostratus

Jun 06, 2017

F5 LTM sending reset packets to Pool member

F5 LTM has a pool member listening on port 8003 and its mainframe server. Pool member is UP but Mainframe console shows consistently F5 is rejecting the connection ( No issues in accessing the VIP )....

Nimbostratus

Jun 07, 2017

I have enabled reset cause in the logs and I see following error.

What does this mean also no issues reported in accessing the VIP. its purely communication between LTM to Node.

Jun 7 07:04:08 local/tmm2 err tmm2[6122]: 01230140:3: RST sent from server91.test.com:8003 to 172.31.x.x:53005, [0x11ca629:5165] RST from BIG-IP internal Linux host Jun 7 07:05:08 local/tmm2 err tmm2[6122]: 01230140:3: RST sent from server91.test.com:8003 to 172.31.x.x:53005, [0x11ca629:5165] RST from BIG-IP internal Linux host

dragonflymr
Cirrostratus
Jun 07, 2017
Hi,

If I can recall RST from BIG-IP internal Linux host is most often related to monitor. Are you using monitor for your Pool or nodes? If so is it marking members/nodes up - guess yes so maybe this counter is unrelated to your issue.

Best option is to trace connection on both sides of BIG-IP:

client -> VIP

BIG-IP -> mainframe

Original trace looks just fine, there is 3WHS, some packets from mainframe to BIG-IP, ACK for those frames and then RST

To be honest it looks like monitor connection from BIG-IP, is src IP 172.31.x.x for packets == to self IP on VLAN facing mainframe?

If so this is most probably monitor traffic - what monitor are you using for your pool/nodes? Is pool monitor http?

HTTP monitor is issuing RST if it received expected Receive String and more packets are coming from monitored host.

Piotr