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Does CEF use TCAM?
CEF-Based MLS Operation and Use of TCAM CEF uses the IP routing table on the Layer 3 forwarding engine to build the FIB. When the adjacency table in TCAM is full, an entry in the FIB table points to the Layer 3 forwarding engine to redirect the adjacency lookup.
What is hardware CEF?
Although CEF is a Cisco proprietary protocol other vendors of multi-layer switches or high-capacity routers offer a similar functionality where layer-3 switching or routing is done in hardware (in an ASIC) instead of by software and the (central) CPU. …
What is the difference between CEF and process switching?
Process switching is the oldest, slowest and most processor intensive. In fast switching, the first packet to a destination is process switched but subsequent packets are forwarded using the information stored in the fast cache. Finally, CEF pre-builds the cache before any packets need to be forwarded.
What is CEF switching?
Cisco Express Forwarding (CEF) switching is a proprietary form of scalable switching intended to tackle the problems associated with demand caching. With CEF switching, the information which is conventionally stored in a route cache is split up over several data structures.
What is difference between CAM and TCAM?
The problem with CAM is that it can only do exact matches on ones and zeros (binary CAMs), and here comes TCAM. TCAM stands for Ternary Content Addressable Memory which can match a third state, which is any value. TCAM is a specialized CAM designed for rapid table lookups.
What are the switching protocols?
Examples of link layer protocols include Ethernet frame switching (connectionless), ATM cell switching (connection), and multiprotocol label switching (MPLS; connection).
On which three values is TCAM matching based?
TCAM matching is based on three values: 0, 1, or x (where x is either number), hence the term “ternary.”
Is the fast-switching cache like the CEF cache?
Regarding the Fast Switching method, does the fast-switching cache could be like the CEF switching, stored either in RAM or in TCAM if the switch has TCAM capability ? Finally, regarding a practical point of view, do a Cisco Catalyst 3850, and Catalyst 4500 have ASIC and TCAM memory ?
What kind of data structure does CEF use?
CEF switching uses a software data structure called FIB in order to determine the output interface to which a packet must be sent. L2 bridging in software has no specific named technique. It’s just called “L2 bridging in software”. Coming now to hardware forwarding.
How does Ethernet frame lookup work in CAM table?
Table lookups are fast! Whenever the switch receives an Ethernet frame it will use a hashing algorithm to create a “key” for the destination MAC address + VLAN and it will compare this hash to the already hashed information in the CAM table. This way it is able to quickly lookup information in the CAM table.
How is information split up in CEF switching?
With CEF switching, the information which is conventionally stored in a route cache is split up over several data structures. The CEF code is able to maintain these data structures in the Gigabit Route Processor (GRP), and also in slave processors such as the line cards in the 12000 routers.