F5 Troubleshooting
This article will talk about Network Troubleshooting in the F5 box but you can read it to see how network Troubleshooting should be
As we know Network Troubleshooting May take hours even days to solve so i decided to share with you a problem that i faced in The F5 box about how to think and solve it in the end
Before we start i wanna to thank my prof Eng Ashraf ELsayed ELshaabany cuz without him i can't do any of this network stuff
Let’s start
The problem ?
As usual i start to make the Nodes , pools and the virtual servers up and make sure they can ping on each other
It’s clear that i wanna to run a Round Robin http virtual server
So the virtual server should work now on 192.168.111.10
The connection has timed out ! , But How the server is runnig well and the nodes is up as you can see
So i tried so solutions that may solve this problem
Analyzing
I opened Wireshark to check the packet translation between the machines and i found that
Tcp Retransmation : TCP Retransmission — Occurs when the sender retransmits a packet after the expiration of the acknowledgement. TCP Fast Retransmission — Occurs when the sender retransmits a packet before the expiration of the acknowledgement timer.
This screens means that we can send our SYN packet but we don't get and ACK packets in return
In the second Pic we see it make the packet for broadcasting to reach the 192.168.111.10 from my other Networks
Maybe the F5 box can't reach the Nodes or what ? , Let's try to ping on them from the F5 box
Make sure you are connected with the F5 box in the same network first
ssh root@10.1.0.200
That's weird cuz it pingable , So i google about this problem and i try some solutions
I try to make a Monitor rule with the ping command and apply it on the Nodes , I see people see that may be the problem
what is monitoring : Monitors determine the availability and performance of devices, links, and services on a network
It's green , This mean that we are good the node is up so i apply the monitor mode to all the nodes also
But we are also can't reach the server
second solution
Maybe The F5 can't forward the packet as we wanna so i tried to manually configure the packet forwarding in the box
tmsh
show /net route 
Seems everything is well configured , Maybe the problem on our machine ?
Third solution
Maybe our machine dosen't forward the tarffic in a right way , This solution i will show you with the pic's all action's that i have been made
It seems that we can't reach the Node from the first , That's my mistake i didn't ping from my machine first on the nodes i just test the ping from the F5 box to the Nodes That's why i told you in the beging of the article you should test the ping on the hole network
So i look at the route table and it seems normal and there is any problem on it , I try a tricky play i will show it to you in the next pic's
I try to make a direct connection between my machine and the F5 cuz it not a real Network it's a virtual one
So i found the Virtual box treat his adapters as a realworld one's so this tricky method is fail also , why i try to configure the F5 forwarding and don't look at my proxy from the first ??
Final solution
So i turned of my machine and make some configurations on my Virtualbox Network adapters , and change the firefox proxy to detect the proxy setting on the network
If you have different browseres like brave you may see this
And , .....
Viva , It works ... , The servers is green as well
So this article is a proof of concept about what is troubleshooting , you should be very patient in this stage cuz it take hours to solve take it easy and always remmeber
A good network engineer is not the one who build the network, but the one who handles the network errors
see you My N1NJ10
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