You can vertically cluster AS instances either by multihoming your machine and passing different values to -b when starting JBoss, or by ensuring each AS uses distinct ports for all services that open ports. AS 4.x supports the latter via the ServiceBindingManager service, which does not work with pojo services (i.e. those that are not deployed via the ServiceController). A number of clustering services that open ports have been converted in AS 5 into pojo services, so the old ServiceBindingManager approach no longer works. Need to find a solution for this.