Limit softwire flows per IPv6 prefix for DS-Lite

Junos OS provides a configurable option to limit the number of softwire flows from a subscriber's Basic Bridging Broadband (B4) device at a given point in time, thus limiting excessive use of addresses within the subnet available to a subscriber. This limitation reduces the risk of denial-of-service (DOS) attacks. To specify the size of the subnet subject to limitation, include the dslite-ipv6-prefix-length prefix-length statement at the [edit services service-set service-set-name softwire-options] hierarchy level. Specify a prefix length of 56, 64, 98, or 128. The show services nat mappings address-pooling-paired operational command output shows the mapping for the prefix. The mapping shows the address of the active B4.