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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2013-11-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001219210</issuerCik>
        <issuerName>IKANOS COMMUNICATIONS</issuerName>
        <issuerTradingSymbol>IKAN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001592611</rptOwnerCik>
            <rptOwnerName>Tallwood Partners, LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TALLWOOD VENTURE CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>3000 SAND HILL ROAD, BLDG 3, STE 240</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001427347</rptOwnerCik>
            <rptOwnerName>TALLWOOD III ANNEX LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TALLWOOD VENTURE CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>3000 SAND HILL ROAD, BLDG 3, STE 240</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025-7113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001347680</rptOwnerCik>
            <rptOwnerName>TALLWOOD III L P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TALLWOOD VENTURE CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>3000 SAND HILL ROAD, BLDG 3, STE 240</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025-7113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001347747</rptOwnerCik>
            <rptOwnerName>TALLWOOD III PARTNERS L P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TALLWOOD VENTURE CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>3000 SAND HILL ROAD, BLDG 3, STE 240</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025-7113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001357894</rptOwnerCik>
            <rptOwnerName>Tallwood III Associates LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TALLWOOD VENTURE CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>3000 SAND HILL ROAD, BLDG 3, STE 240</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>64025-7113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001470833</rptOwnerCik>
            <rptOwnerName>Tallwood III Management LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TALLWOOD VENTURE CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>3000 SAND HILL ROAD, BLDG 3, STE 240</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001470838</rptOwnerCik>
            <rptOwnerName>Tallwood III Annex Management LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TALLWOOD VENTURE CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>3000 SAND HILL ROAD, BLDG 3, STE 240</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025-7113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001134607</rptOwnerCik>
            <rptOwnerName>BANATAO DIOSDADO P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O TALLWOOD VENTURE CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>3000 SAND HILL ROAD, BLDG 3, STE 240</rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025-7113</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-11-07</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2000000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2000000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>16000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Diosdado P. Banatao</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>29616475</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Tallwood Partners, LLC (&quot;Partners&quot;) is the direct owner of the shares reported as acquired herein.  The Banatao Living Trust DTD 7/21/99 (&quot;Trust&quot;) is the managing member of Partners.</footnote>
        <footnote id="F2">Diosdado P. Banatao, as a trustee of the Banatao Living Trust DTD 7/21/99, directly or indirectly, holds 100% of the membership interests in Tallwood Partners, LLC, and holds shared voting and dispositive power over the securities held by this entity, but disclaims such beneficial ownership except to the extent of his pecuniary interest therein. The filing of this statement shall not be deemed an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, the Reporting Person is the beneficial owner of these shares.</footnote>
        <footnote id="F3">Tallwood III Annex, L.P. (&quot;Tallwood III Annex&quot;) Tallwood III, L.P. (&quot;Tallwood III&quot;), Tallwood III Partners, L.P. (&quot;Tallwood III Partners&quot;), Tallwood III Associates, L.P. (&quot;Tallwood III Associates&quot; and, together with Tallwood III Annex, Tallwood III and Tallwood III Partners, the &quot;Tallwood Funds&quot;) directly own 18,187,904, 10,074,743, 1,275,771 and 78,057 shares of Common Stock of the Company, respectively. (Continued in Footnote 4).</footnote>
        <footnote id="F4">Tallwood III Management, LLC (&quot;Tallwood Management&quot;) is the general partner of Tallwood III, Tallwood III Partners and Tallwood III Associates. Tallwood III Annex Management, LLC (&quot;Tallwood Annex Management&quot;) is the general partner of Tallwood III Annex. Tallwood Management may be deemed to share voting and dispositive power with respect to the shares owned by Tallwood III, Tallwood III Partners and Tallwood III Associates, but disclaim such beneficial ownership except to the extent of its pecuniary interest therein. Tallwood Annex Management may be deemed to share voting and dispositive power with respect to the shares owned by Tallwood III Annex, but disclaim such beneficial ownership except to the extent of its pecuniary interest therein. (Continued in Footnote 5).</footnote>
        <footnote id="F5">Diosdado P. Banatao is a managing member of Tallwood Management and Tallwood Annex Management and may be deemed to share voting and dispositive power with respect to the shares owned by the Tallwood Funds, but disclaims such beneficial ownership except to the extent of his pecuniary interest therein. The filing of this statement shall not be deemed an admission that, for purposes of Section 16 of the Securities Exchange Act of 1934 or otherwise, Mr. Banatao is the beneficial owner of these shares.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Natasha Skok, as Atty-in-Fact for Tallwood III Management, LLC as General Partner for Tallwood III, L.P.</signatureName>
        <signatureDate>2013-11-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Natasha Skok, as Atty-in-Fact for Tallwood III Management, LLC as General Partner for Tallwood III Partners, L.P.</signatureName>
        <signatureDate>2013-11-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Natasha Skok, as Atty-in-Fact for Tallwood III Management, LLC as General Partner for Tallwood III Associates, L.P.</signatureName>
        <signatureDate>2013-11-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Natasha Skok, as Atty-in-Fact for Tallwood III Management, LLC</signatureName>
        <signatureDate>2013-11-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Diosdado P. Banatao</signatureName>
        <signatureDate>2013-11-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Diosdado P. Banatao, trustee of the Banatao Living Trust DTD 7/21/99, Managing Member of Tallwood Partners, LLC</signatureName>
        <signatureDate>2013-11-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Natasha Skok, as Atty-in-Fact for Tallwood III Annex Management, LLC as General Partner for Tallwood III Annex, L.P.</signatureName>
        <signatureDate>2013-11-21</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Natasha Skok, as Atty-in-Fact for Tallwood III Annex Management, LLC</signatureName>
        <signatureDate>2013-11-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
