BGP Config Question, IP Address-family

[mdargin]

What is the purpose of having just the: address family ip4 command configured in BGP. What is the real world purpose of it? I know it is off by default but what do I gain from having it configured.

I am confused by Cisco's websites explanation of it that it enables routing session such as BGP to use standard IP version 4 address prefixes.

What are standard IP version 4 address prefixes. I thought BGP by default routes IP 4

I am confused by this.

The router that I inherited configuration looks like this.

Router Bgp 208

address-family ip4

Thank You for any responses

[cdusio]

This command is for MBGP extenstions and allows you to configure address family unicast and multicast addresses within the address family. Refer to

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_command_reference_chapter09186a00800ca69b.html#1024841

Chris