<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType>

    <periodOfReport>2004-04-16</periodOfReport>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001043604</issuerCik>
        <issuerName>JUNIPER NETWORKS INC</issuerName>
        <issuerTradingSymbol>JNPR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001270521</rptOwnerCik>
            <rptOwnerName>KOLLURI KRISHNA KITTU</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1194 NORTH MATHILDA AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SUNNYVALE</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94089</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>GM, Security Products Group</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>288014</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>42471</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>by Trust</value>
                    <footnoteId id="F3"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Incentive Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F6"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>203223</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Non-Qualified Stock Option (right to buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F8"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F7"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>280800</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Received in exchange for 205,138 shares of Netscreen Technologies, Inc. common stock in connection with the merger of Netscreen Technologies into Juniper Networks, Inc. (the &quot;Merger&quot;).  On the effective date of the Merger, the closing price of Netscreen Tehnology Inc.'s common stock was  $35.11 and the closing price of Juniper Networks, Inc.'s common stock was $25.17.</footnote>
        <footnote id="F2">Received in exchange for 30,250 shares of Netscreen Technologies, Inc. common stock in connection with the merger of Netscreen Technologies into Juniper Networks, Inc. (the &quot;Merger&quot;).  On the effective date of the Merger, the closing price of Netscreen Tehnology Inc.'s common stock was  $35.11 and the closing price of Juniper Networks, Inc.'s common stock was $25.17.</footnote>
        <footnote id="F3">Held by the Kolluri LivingTrust over which the Reporting Person exercises investment and voting control.</footnote>
        <footnote id="F4">Vests as to 25% of the shares subject to the option on the first anniversary of the date of grant and monthly thereafter as to 1/48th of the shares subject to the option.</footnote>
        <footnote id="F5">The option was originally granted under the Neoteris, Inc. 2001 Stock Option Plan and expires on 2/27/2013.</footnote>
        <footnote id="F6">Received in the Merger in exchange for stock option to acquire 144,746 shares of Netscreen Technology, Inc. at $1.21 per share.</footnote>
        <footnote id="F7">The option was originally granted under the Netscreen Technologies, Inc. 2001 Equity Incentive Plan and expires on 11/27/2013.</footnote>
        <footnote id="F8">Received in the Merger in exchange for stock option to acquire 200,000 shares of Netscreen Technology, Inc. at $25.31 per share.</footnote>
    </footnotes>

    <remarks>Exhibit List</remarks>

    <ownerSignature>
        <signatureName>By: Mitchell L. Gaynor, attorney-in-fact  For: Krishna Kolluri</signatureName>
        <signatureDate>2004-04-19</signatureDate>
    </ownerSignature>
</ownershipDocument>

