# Switch Fabric Bandwidth Configuration

By default, the switch fabric for the ERX1440, ERX310, E120, and E320 Broadband Services Routers uses a bandwidth weighting ratio of 15:2 for multicast-to-unicast weighted round robin (WRR). In the absence of strict-priority traffic, and when both unicast and multicast traffic compete for switch fabric bandwidth, the switch fabric allocates 15/17ths of the available bandwidth to multicast traffic and 2/17ths of the available bandwidth to unicast traffic.

You can use the fabric weights command to change the ratio for multicast to unicast traffic on the router switch fabric. For more information about the fabric weights command, see Managing the System in the JunosE System Basics Configuration Guide.

#### Related Documentation

- IPv6 Multicast Overview
- fabric weights