Drop IPv6 Subnet-router Anycast Address Traffic

By default, traffic destined for IPv6 subnet-router anycast addresses is allowed. However, you can deny the traffic for reasons such as preventing a DDoS attack. For more information, see Prevention of DDoS attack on IPv6 Subnet-router Anycast Addresses.

Access global configuration mode.
```
device# configure terminal
```
Enable hardware to drop traffic destined for IPv6 subnet-router anycast addresses.
```
device(config)# ipv6 subnet-zero drop
```