A method for managing a plurality of tenant networks spanning a plurality of physical sites, the method comprising: configuring a particular managed forwarding element, 'MFE', at a multi-tenant site to implement a first logical forwarding element, 'LFE', and a second logical forwarding element, LFE,, wherein the first LFE is for forwarding packets for a first tenant logical network and the second LFE is for forwarding packets for a second tenant logical network, the method characterised by: wherein the first LFE comprises a first logical port that is mapped to a first extender MFE at a first tenant site belonging to the first tenant network and a first set of additional logical ports that are mapped to a first set of machines (162, 164, 170) operating at the multi-tenant site, wherein the second LFE comprises a second logical port that is mapped to a second extender MFE at a second tenant site belonging to the second tenant network and a second set of additional logical ports that are mapped to a second set of machines (166, 168, 172, 174) operating at the multi-tenant site; and forwarding, by the particular MFE, a first packet sent from one of the machines of the first set of machines (162, 164, 170) to the first extender MFE at the first tenant site by mapping the first packet to the first logical port of the first LFE, and forwarding, by the particular MFE, a second packet sent from one of the machines of the second set of machines (166, 168, 172, 174) to the second extender MFE at the second tenant site by mapping the second packet to the second logical port of the second LFE. configuring a particular managed forwarding element, 'MFE', at a multi-tenant site to implement a first logical forwarding element, 'LFE', and a second logical forwarding element, LFE,, wherein the first LFE is for forwarding packets for a first tenant logical network and the second LFE is for forwarding packets for a second tenant logical network, the method characterised by: wherein the first LFE comprises a first logical port that is mapped to a first extender MFE at a first tenant site belonging to the first tenant network and a first set of additional logical ports that are mapped to a first set of machines (162, 164, 170) operating at the multi-tenant site, wherein the second LFE comprises a second logical port that is mapped to a second extender MFE at a second tenant site belonging to the second tenant network and a second set of additional logical ports that are mapped to a second set of machines (166, 168, 172, 174) operating at the multi-tenant site; and forwarding, by the particular MFE, a first packet sent from one of the machines of the first set of machines (162, 164, 170) to the first extender MFE at the first tenant site by mapping the first packet to the first logical port of the first LFE, and forwarding, by the particular MFE, a second packet sent from one of the machines of the second set of machines (166, 168, 172, 174) to the second extender MFE at the second tenant site by mapping the second packet to the second logical port of the second LFE. wherein the first LFE comprises a first logical port that is mapped to a first extender MFE at a first tenant site belonging to the first tenant network and a first set of additional logical ports that are mapped to a first set of machines (162, 164, 170) operating at the multi-tenant site, wherein the second LFE comprises a second logical port that is mapped to a second extender MFE at a second tenant site belonging to the second tenant network and a second set of additional logical ports that are mapped to a second set of machines (166, 168, 172, 174) operating at the multi-tenant site; and forwarding, by the particular MFE, a first packet sent from one of the machines of the first set of machines (162, 164, 170) to the first extender MFE at the first tenant site by mapping the first packet to the first logical port of the first LFE, and forwarding, by the particular MFE, a second packet sent from one of the machines of the second set of machines (166, 168, 172, 174) to the second extender MFE at the second tenant site by mapping the second packet to the second logical port of the second LFE.