A host identification service 270 can be coupled to the different racks 230, 232 and can perform health checks on the corresponding server computers. Through the health checks, discovery information 272 can be obtained including an identification (e.g., an IP address) of each host server computer in the POP 130. The discovery information 272 can be shared with the host server computers such that each host server computer knows the identification of all other active host server computers in the POP. Such identification information from the host identification service 270 can be used to generate pre-computed header templates. As described further below, an intra-domain redirected packet 280 is treated differently than an inter-domain redirected packet 282. More specifically, the header information used to encapsulate the intra-domain packet 280 is a multicast message, whereas the header information used to encapsulate the inter-domain message 282 is a point-to-point message using a MAC address of a gateway between the two switches 234, 236. In the inter-domain communication 282, a packet can be transmitted from the first host server computer 289, via the gateway associated with switches 234, 252, to a second host server computer 290. The intra-domain packet redirection 280 can be accomplished by a first host server computer 287 transmitting to the second host server computer 289 in the same domain. Such a communication can pass via the switch 234.