ITD (Intelligent Traffic Director) is a hardware based multi-Tbps Layer 4 load-balancing, traffic steering and clustering solution on Nexus 5K/6K/7K series of switches. It supports IP-stickiness, resiliency, NAT, (EFT), VIP, health monitoring, sophisticated failure handling policies, N+M redundancy, IPv4, IPv6, VRF, weighted load-balancing, bi-directional flow-coherency, and IPSLA probes including DNS.
ITD is much superior than legacy solutions like PBR, WCCP, ECMP, port-channel, layer-4 load-balancer appliances.
For example, ITD comparison with WCCP:
Appliance is unaware of the protocol
Number of TCAM entries
(say, 100 SVI, 8 nodes, 20 ACEs)
User can specify which bits to use for load-balancing
Number of nodes
Support for IPSLA probes
Support for Virtual IP
Support for L4-port load-balancing
Capability to choose src or dest IP for load-balancing
Customer support needs to look at switch only, or both the switch and appliance