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MPLS Fundamentals by Luc De Ghein - CCIE No. 1897

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CEF Switching Packets in Hardware

To achieve high rate packet forwarding, the router can use ASICs on the boards or line cards. These ASICs are specially built chips that can forward packets at the highest rate. To have the ASICs forward the packets per the routing table, the router distills the CEF table into the ASIC so that it is correctly programmed to forward the packets. Example 6-5 shows the Packet Switching ASIC (PSA) on an engine 2 line card of the GSR 12000 series, programmed to switch packets. You see the forwarding entry for the prefix 10.1.2.5/32.

Example 6-5. CEF Table (FIB) in ASIC
berlin#execute-on slot 7 show ip psa-cef 10.1.2.5 255.255.255.255 detail ========= Line Card (Slot 7) ======= Leaf FCR 7 0x7006F1E0 found 3 deepFast ...

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