A non-solicitation agreement restricts an individual (usually a former employee) from soliciting either (a) employees or (b) customers of a business after leaving the business. Non-solicitation language can come in the form of an entire document or a clause within another document, like an employment agreement or independent contractor agreement.

Many companies require managers and professionals to sign non-solicitation agreements to prevent them from soliciting (a) current employees, or (b) current customers.

The most common issue in non-solicitation agreements is that if they are not "reasonable" (as defined on a case-by-case basis), they can be considered to be restraint of trade. That is, the agreement unreasonably restricts someone from doing business.

A lawsuit is filed and a court decides, or in some cases a state has laws limiting restrictive covenants like non-solicitation agreements.

In your case since the client n more work with your current employer, this agreement may not hamper the proposed employment with the ex client of your current company.

Well, you can challenge the legal problems if any arises on this ground also.

1) any agreement in restraint of trade is void under section 27 of indian contract act

2) after you resign and leave the organisation you are at liberty to take a job in competitor organisation

since you resigned in june 2016 you are at liberty to join the client

2) company cannot demand money from you for lost business

3) your current employer can request the client not to hire your services

If your company lost heier business with that client, how can you be held responsible for that.

Your company only has to introspect the reasons.

Your employer cannot dictate terms to that client for any reason, that client may sue your company if it is going beyond the agreement or conditions that have been broken after termination of their contract.

In any case you cannot be held for violation of solicitation treaty that you have been made to sign.

A clause which prevents you from soliciting work from any of the clients of your employer is absolutely enforceable through a lawsuit for injunction. Your employer may file a suit for injunction to restrain you from working with this client and it may also seek damages for the breach of contract.

Both you and client can be made the parties in the suit for injunction by your employer.