I have submitted a paper in IETE Journal of Research (http://www.tandfonline.com/loi/tijr20#.VrL0xvl97IW) on 22/09/15. Still the status is under review. Is it usual for this journal or I should make a polite query to the editor.
Although I have never submitted to this journal, in my experience, this is not an unusually long period of time, especially given all the delays that can stack up during peer review.
This has also been studied recently, with typical turnaround times of 14 weeks. When you consider the holiday break that many academics likely took in Dec/Jan, this is right in line with your delay.
That being said, after 4 months, I don't think many editors would mind a quick email to ask for an update. The last time I did this, the editor explained that they had had an unusually difficult time in finding reviewers. However, do be polite and respectful of their time when you write the editor.