Identification of paths in a network of mixed routing/switching devices

A computer implemented method of identifying a next hop for a flow of traffic through a focus device in a path of interconnected devices including switching devices and routing devices, wherein the switching devices operate according to a switching address protocol and the routing devices operate according to a routing address protocol, the method implemented at a management computer having a query path to the interconnected devices and comprising:

• for the focus device which is one of the routing devices and which is configured to receive traffic addressed to a terminal destination, dispatching a query message containing a query key based on a destination identifier for the terminal destination from the management computer to the focus device, the query message causing the focus device to identify and supply a next routing address for a hypothetical message addressed to the terminal destination;
• receiving, from the focus device, a result message containing a new routing address which is the next routing address;
• ascertaining from the new routing address a corresponding switching address which is a switching address for switching traffic at one of the switching devices in a direction to the terminal destination;
• using the switching address in a subsequent query key for a subsequent query message directed to said one of the switching devices;
• directing the subsequent query message to a forwarding database at said one of the switching devices, the subsequent query message causing said one of the switching devices to identify and supply an egress port for the switching address at said one of the switching devices,
• wherein the query message and subsequent query message are transmitted from the management computer over the network, while the network is active and there is a flow of traffic between the interconnected devices, wherein the query message and subsequent query message do not constitute the flow of traffic for which the next hop is to be determined.

A computer implemented method of identifying a next hop from a focus device in a path of interconnected devices including switching devices and routing devices, wherein a switching device operates according to a switching address protocol and a routing device operates according to a routing address protocol, the method implemented at a management computer having a query path to the interconnected devices and comprising:

• for the focus device which is one of the routing devices and which is configured to receive traffic addressed to a terminal destination, the traffic comprising packets which each carry a VLAN identifier which identifies which VLAN is used to route the packet, the step of dispatching a query message containing a query key based on a destination identifier for the terminal destination from the management computer to the focus device, the query message causing the focus device to identify and supply a next routing address for a hypothetical packet addressed to the terminal destination;
• receiving, from the focus device, a result message containing a new routing address which is the next routing address;
• ascertaining from the new routing address a corresponding switching address which is a switching address for switching traffic at one of the switching devices in a direction to the terminal destination, wherein the switching address is ascertained from a mapping table which maps routing addresses to switching addresses;
• using the switching address in a subsequent query key of a subsequent query message directed to said one of the switching devices, wherein the subsequent query message is directed to a forwarding database at said one of the switching devices, the forwarding database identified by the VLAN identifier;
• and
• if the forwarding database at said one of the switching devices does not contain an entry for an egress port for traffic addressed to the terminal destination, querying the mapping table that was used to map the routing address to the switching address, thereby identifying an interface from which the mapping between the routing and switching address was learned.