Hello Sathish
EIGRP is a Cisco proprietary protocol, however, in 2013, Cisco permitted other vendors to freely implement a limited version of EIGRP with some of its associated features such as High Availability while withholding other EIGRP features. Information needed for implementation was published in RFC 7868.
This resulted in the free use of the protocol by other vendors, at least the features that Cisco allowed. So there are vendors other than that support EIGRP, and they can interconnect with Cisco equipment as well.
I hope this has been helpful!
Laz