Home » Cisco » 642-889 » Which option is used as a loop prevention mechanism to support MPLS VPN customers with multihomed sites?
Which option is used as a loop prevention mechanism to support MPLS VPN customers with multihomed sites?
A. BGP down bit
B. sham links
C. AS override
D. SOO extended BGP community
E. allow as-in
Correct Answer: D
Explanation/Reference:
Explanation:
http://www.cisco.com/en/US/docs/ios/12_4t/12_4t11/htbgpsoo.html
Site of Origin BGP Community Attribute
The site-of-origin (SoO) extended community is a BGP extended community attribute that is used to identify routes that have originated from a site so that the readvertisement of that prefix back to the source site can be prevented. The SoO extended community uniquely identifies the site from which a router has learned a route. BGP can use the SoO value associated with a route to prevent routing loops.
