A method for use in processing route data in a network comprising a plurality of autonomous systems, the method comprising: at a network device, receiving, from at least one border network device in the network, route data defining at least one route for network traffic which is configured on the at least one border network device, wherein the at least one border network device is located at a border of an autonomous system in the plurality of autonomous systems; at the network device: processing the received route data according to a set of policies to generate modified route data, wherein the generating of the modified route data comprises inserting metadata which defines one or more modifications to the at least one route into the received route data, and wherein either (i) the modified route data includes a data field that indicates where the route data was received from and the data field is left blank or is filled in with dummy data that does not identify the at least one border network device or (ii) the modified route data does not include a data field that indicates where the route data was received from; and transmitting, to the at least one border network device, at least a part of the modified route data, wherein the at least part of the modified route data does not comprise data indicating that the route data was previously received from the at least one border network device, wherein the at least part of the modified route data comprises the metadata and wherein the metadata is operable to instruct the at least one border network device to modify the behavior of the at least one route, wherein the behaviour modification comprises one or more of installing, withdrawing, promoting and demoting the at least one route. at a network device, receiving, from at least one border network device in the network, route data defining at least one route for network traffic which is configured on the at least one border network device, wherein the at least one border network device is located at a border of an autonomous system in the plurality of autonomous systems; at the network device: processing the received route data according to a set of policies to generate modified route data, wherein the generating of the modified route data comprises inserting metadata which defines one or more modifications to the at least one route into the received route data, and wherein either (i) the modified route data includes a data field that indicates where the route data was received from and the data field is left blank or is filled in with dummy data that does not identify the at least one border network device or (ii) the modified route data does not include a data field that indicates where the route data was received from; and transmitting, to the at least one border network device, at least a part of the modified route data, wherein the at least part of the modified route data does not comprise data indicating that the route data was previously received from the at least one border network device, wherein the at least part of the modified route data comprises the metadata and wherein the metadata is operable to instruct the at least one border network device to modify the behavior of the at least one route, wherein the behaviour modification comprises one or more of installing, withdrawing, promoting and demoting the at least one route. processing the received route data according to a set of policies to generate modified route data, wherein the generating of the modified route data comprises inserting metadata which defines one or more modifications to the at least one route into the received route data, and wherein either (i) the modified route data includes a data field that indicates where the route data was received from and the data field is left blank or is filled in with dummy data that does not identify the at least one border network device or (ii) the modified route data does not include a data field that indicates where the route data was received from; and transmitting, to the at least one border network device, at least a part of the modified route data, wherein the at least part of the modified route data does not comprise data indicating that the route data was previously received from the at least one border network device, wherein the at least part of the modified route data comprises the metadata and wherein the metadata is operable to instruct the at least one border network device to modify the behavior of the at least one route, wherein the behaviour modification comprises one or more of installing, withdrawing, promoting and demoting the at least one route.