Hello Ahmed
When the filtering mechanism is enabled on each router, it is applied for all networks whether those networks exist on the local router or are received and transmitted by intervening routers. What this means is that R2 will see 1.1.1.1 and 3.3.3.3 labelled while 11.11.11.11 and 33.33.33.33 will not have labels, as expected.
Similarly, R1 will see that 2.2.2.2 is labelled while 22.22.22.22 will not have labels, again as expected. However, because R3 sends its information to R1 via R2, the mpls ldp advertise-labels for 1 command applied to R2 will also filter out those routes delivered from R3. So since both 3.3.3.3 and 33.33.33.33 are filtered out using R2’s filtering mechanism, these arrive at R1 untagged.
A similar situation occurs for routes that are advertised from R1 to R3 which affects how they appear in R3.
I hope this has been helpful!
Laz