A logical packet switching device, comprising: a first physical device including a plurality of first ingress line cards, a plurality of first ports, a first switching fabric, and a plurality of first egress line cards (111, 116-119); and a second physical device including a plurality of second ingress line cards, a plurality of second ports, a second switching fabric, and a plurality of second egress line cards (131, 136-139); wherein the first and second physical devices (110, 130) are each configured to extend a switching fabric of the logical packet switching device between the first and second physical devices (110, 130) over one or more standard-protocol networks coupled to one or more of the plurality of first ports and to one or more of the plurality of second ports; wherein said extending of the switching fabric of the logical packet switching device includes: the first physical device sending packets including second fabric information for use by the second switching fabric in switching corresponding packets to one or more egress line cards of the plurality of second egress line cards, and the second physical device sending packets including first fabric information for use by the first switching fabric in switching corresponding packets to one or more egress line cards of the plurality of first egress line cards, wherein the first physical device is configured to perform a first ingress lookup operation for a particular packet on a particular first ingress line card of the plurality of first ingress line cards to determine a particular second egress line card of the plurality of second egress line cards (131, 136-139), to forward the particular packet with said second fabric information including an identification of the particular second egress line card through the first switching fabric to a particular first port of the plurality of first ports, and then to send the particular packet with the second fabric information from the particular first port; and wherein the second physical device is configured to receive the particular packet with the second fabric information on a particular second port of the plurality of second ports (131, 136-139) communicatively coupled via said one or more standard-protocol networks to the particular first port, to forward the particular packet through the second switching fabric to the particular second egress line card based on the identification of the particular second egress line card in said second fabric information, and process the particular packet on the particular second egress line card including performing an egress lookup operation and sending the particular packet from the logical packet switching device from the particular second egress line card. a first physical device including a plurality of first ingress line cards, a plurality of first ports, a first switching fabric, and a plurality of first egress line cards (111, 116-119); and a second physical device including a plurality of second ingress line cards, a plurality of second ports, a second switching fabric, and a plurality of second egress line cards (131, 136-139); wherein the first and second physical devices (110, 130) are each configured to extend a switching fabric of the logical packet switching device between the first and second physical devices (110, 130) over one or more standard-protocol networks coupled to one or more of the plurality of first ports and to one or more of the plurality of second ports; wherein said extending of the switching fabric of the logical packet switching device includes: the first physical device sending packets including second fabric information for use by the second switching fabric in switching corresponding packets to one or more egress line cards of the plurality of second egress line cards, and the second physical device sending packets including first fabric information for use by the first switching fabric in switching corresponding packets to one or more egress line cards of the plurality of first egress line cards, wherein the first physical device is configured to perform a first ingress lookup operation for a particular packet on a particular first ingress line card of the plurality of first ingress line cards to determine a particular second egress line card of the plurality of second egress line cards (131, 136-139), to forward the particular packet with said second fabric information including an identification of the particular second egress line card through the first switching fabric to a particular first port of the plurality of first ports, and then to send the particular packet with the second fabric information from the particular first port; and wherein the second physical device is configured to receive the particular packet with the second fabric information on a particular second port of the plurality of second ports (131, 136-139) communicatively coupled via said one or more standard-protocol networks to the particular first port, to forward the particular packet through the second switching fabric to the particular second egress line card based on the identification of the particular second egress line card in said second fabric information, and process the particular packet on the particular second egress line card including performing an egress lookup operation and sending the particular packet from the logical packet switching device from the particular second egress line card.