A method comprising: determining, by a centralized controller of a network, that one or more first network devices (18A, 16A) of a plurality of network devices for the network are In-Service Software Upgrade, ISSU,-capable and that a second network device (18B, 16B) of the plurality of network devices is not ISSU-capable, wherein the one or more first network devices that are ISSU-capable are configured to at least one of process or forward network traffic while performing a software upgrade, and wherein the second network device that is not ISSU-capable is unable to process or forward network traffic while performing the software upgrade; transmitting, by the centralized controller, one or more messages instructing the one or more first network devices to perform an ISSU operation; and transmitting, by the centralized controller, one or more messages instructing the second network device to transmit a message to one or more neighbor network devices (16A, 18A, 18M, 16N) of the plurality of network devices that neighbor the second network device, wherein the message: indicates that the second network device is not ISSU-capable; and directs the one or more neighbor network devices of the plurality of network devices to redirect traffic to avoid forwarding the traffic to the second network device by: removing, from a Routing Information Base of the one or more neighbor network devices, an entry describing the second network device; and/or calculating a new route to reach a destination of the traffic, wherein the new route includes a third network device as a next hop, and storing the new route in a Forwarding Information Base of the one or more neighbor network devices. determining, by a centralized controller of a network, that one or more first network devices (18A, 16A) of a plurality of network devices for the network are In-Service Software Upgrade, ISSU,-capable and that a second network device (18B, 16B) of the plurality of network devices is not ISSU-capable, wherein the one or more first network devices that are ISSU-capable are configured to at least one of process or forward network traffic while performing a software upgrade, and wherein the second network device that is not ISSU-capable is unable to process or forward network traffic while performing the software upgrade; transmitting, by the centralized controller, one or more messages instructing the one or more first network devices to perform an ISSU operation; and transmitting, by the centralized controller, one or more messages instructing the second network device to transmit a message to one or more neighbor network devices (16A, 18A, 18M, 16N) of the plurality of network devices that neighbor the second network device, wherein the message: indicates that the second network device is not ISSU-capable; and directs the one or more neighbor network devices of the plurality of network devices to redirect traffic to avoid forwarding the traffic to the second network device by: removing, from a Routing Information Base of the one or more neighbor network devices, an entry describing the second network device; and/or calculating a new route to reach a destination of the traffic, wherein the new route includes a third network device as a next hop, and storing the new route in a Forwarding Information Base of the one or more neighbor network devices. indicates that the second network device is not ISSU-capable; and directs the one or more neighbor network devices of the plurality of network devices to redirect traffic to avoid forwarding the traffic to the second network device by: removing, from a Routing Information Base of the one or more neighbor network devices, an entry describing the second network device; and/or calculating a new route to reach a destination of the traffic, wherein the new route includes a third network device as a next hop, and storing the new route in a Forwarding Information Base of the one or more neighbor network devices. removing, from a Routing Information Base of the one or more neighbor network devices, an entry describing the second network device; and/or calculating a new route to reach a destination of the traffic, wherein the new route includes a third network device as a next hop, and storing the new route in a Forwarding Information Base of the one or more neighbor network devices.