$6.[$Self$-$Learning Switch, $18$ pt$]$ Consider the LAN below consisting of $10$ computers connected by two self$-$learning Ethernet switches. The switch on the left is switch $1$ and the switch on the right is switch $2.$ At $\backslash ($ t$=0\backslash ),$ the switch table entries for both switches are empty.

At $\backslash ($ t$=1,2\backslash ),$ and $3,$ a source node sends to a destination node as described below, and the destination replies immediately $($well before the next time unit$)$:

$-\backslash ($ t$=1$: L $\backslash$rightarrow $1\backslash )$

$-\backslash ($ t$=2$: E $\backslash$rightarrow F $\backslash )$

$-\backslash ($ t$=3$: F $\backslash$rightarrow D $\backslash )$

Describe the two updated switch tables after each time unit $($assuming both the sending frame and the reply frame have gone through the switch.$)$ Assume TTL is $60$ minutes for each table entry.

$*$Note a switch table may be updated by the flooding from the other switch due to selflearning.