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There's also a nice series of articles by Saku Ytti on the ddos protection systems in the Juniper. Here's a window in to one of them:
http://blog.ip.fi/2014/03/quick-look-at-trio-ddos-protection-with.html
Cisco Example
The Cisco example uses IOS-XR for Local Packet Transport Services. Hardware policers on the line cards limit traffic sent up the stack. Packets per second are defined for three types of BGP traffic. bgp-cfg-peer are new sessions and sessions that are not yet 'Established.' bgp-know are established sessions and bgp-default is the 'default' entry for bgp traffic; things not falling in to other buckets, etc.
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