SQL & PL/SQL :: Data Migration From Table To Table?

I Have two DB s with same tables, I need to insert the data from db1 tables to db2 tables. Primary ID starts from 1 on both the tables.

EXample:

Table1:
ID Name c3 c4 c5
1 Oracle1 x y b
2 Oracle2 x n b
3 Oracle3 x f b
4 Oracle4 x f b
5 Oracle5 x f b

Table2:

ID Name c3 c4 c5
1 ONT1 t y t
2 ONT2 t m h
3 ONT2 t b n

All the table1 data should be moved to table2..... Desired out put should be like following

ID Name c3 c4 c5
1 ONT1 t y t
2 ONT2 t m h
3 ONT2 t b n
4 Oracle1 x y b
5 Oracle2 x n b
6 Oracle3 x f b
7 Oracle4 x f b
8 Oracle5 x f b

Data volume is huge... There are 1500 tables and on an average there 10 Million records per table. Currently I am using DB links