POWER OF ATTORNEY

      The undersigned, as a Section 16 reporting person of Arista Networks, Inc.
(the "Company"), hereby constitutes and appoints Isabelle Bertin-Bailly, Ita
Brennan and Marc Taxay, the undersigned's true and lawful attorneys-in-fact to:

      1.	complete and execute Forms 3, 4 and 5 and other forms and all
amendments thereto as such attorneys-in-fact shall in their discretion determine
to be required or advisable pursuant to Section 16 of the Securities Exchange
Act of 1934 (as amended) and the rules and regulations promulgated thereunder,
or any successor laws and regulations, as a consequence of the undersigned's
ownership, acquisition or disposition of securities of the Company; and

      2.	do all acts necessary in order to file such forms with the Securities
and Exchange Commission, any securities exchange or national association, the
Company and such other person or agency as the attorneys-in-fact shall deem
appropriate.

     The undersigned hereby ratifies and confirms all that said
attorneys-in-fact and agent shall do or cause to be done by virtue hereof.  The
undersigned acknowledges that the foregoing attorneys-in-fact, in serving in
such capacity at the request of the undersigned, is not assuming, nor is the
Company assuming, any of the undersigned's responsibilities to comply with
Section 16 of the Securities Exchange Act of 1934 (as amended).

      This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
Company and the foregoing attorneys-in-fact.

       IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to
be executed as of this 18th day of June, 2021.
Signature:  /s/Lewis Chew_
Print Name:  Lewis Chew