Contents
What is Cam and TCAM memory used for?
CAM and TCAM memory. When using TCAM – Ternary Content Addressable Memory inside routers it’s used for faster address lookup that enables fast routing. In switches CAM – Content Addressable Memory is used for building and lookup of mac address table that enables L2 forwarding decisions.
How does CAM work in random access memory?
Random Access Memory (RAM) performs lookups using a memory address and which then returns the data from the address. CAM lookups do the opposite. A function calls the CAM by passing a key that consists of data word structure and the CAM lookup returns memory addresses.
How is the CAM table stored in the switch?
The switch stores the CAM table in the RAM. The RAM is a temporary memory. All contents stored in the RAM are wiped out automatically when we turn off the switch. To preserve the changes which we make in the running-configuration, the switch allows us to copy the running-configuration into the NVRAM. The NVRAM is a permanent memory.
How is Cam memory used in Layer 2?
In Layer 2 world of switches, CAM memory is most used as it enables the switch to build and lookup MAC address tables. MAC address is always unique and so CAM architecture and ability to search for only exact matches is perfect for MAC address lookup.
What’s the difference between Cam and ordinary RAM?
In the case of ordinary RAM the IOS uses a memory address to get the data stored at this memory location, while with CAM the IOS does the inverse. It uses the data and the CAM returns the address where the data is stored.
Why is TCAM memory is so power hungry?
This also explains why TCAM memory is so power hungry. It needs to power on all circuits to be able to make a search not only the matched ones. Limited memory space and power consumption associated with a large amount of parallel active circuitry are the main issues with TCAM.
What are the results of the TCAM table?
TCAM provides three results: 0, 1, and “don’t care.”. TCAM is most useful for building tables for searching on longest matches such as IP routing tables organized by IP prefixes. The TCAM table stores ACL, QoS and other information generally associated with upper-layer processing.