# Edge Data Center Organization and Optimization by Using Cage Graphs
## 7 Experimental Analysis
### Alternative Method of Packet Forwarding  
Network traffic is processed at either layer 2 or 3 of the OSI model, where the former is traditionally made by switches. The latter is typically achieved by routers. For the former, a switch composes its own MAC address table on the fly by inspecting the source MAC addresses of the frames coming in through any of their ports and by either adding a new register if such an address is not found in its own table or otherwise resetting the timer of that register within its own table if it does exist. For the latter, a router fills in its own routing table by reflecting either its directly connected routes or the routes statically configured by a network administrator; otherwise, the table is filled by receiving routing updates from other layer-3 devices being part of the same routing domain upon the same routing protocol.  
When a switch receives a frame, it reads its destination MAC address and searches it through the registers within its own forwarding table. As MAC addresses contain 48 bits, all of them need to match. Comparing a bit requires a bitwise AND logical operation; hence, 48 AND gates are necessary to obtain a match. There are diverse methods to perform this, such that a matching operation halts when any of the bits do not match, thus avoiding the repeated comparison of all bits, although the number of such operations within a matching lookup depends on the number of entries within the MAC address table and how quick a matching entry is found.  
When a router receives a packet, it reads its destination IP address and tries to accommodate it within any of the network addresses registered within the routing table. IPv4 addresses contain 32 bits, although the length of a network address depends on its subnet mask, with a most common value of 24 bits. As shown above, a bitwise AND logical operation is needed to compare a bit, meaning an AND gate for each of those comparisons, whose number depends on the amount of entries installed in the routing table and how fast a matching entry is found.  
An alternative method of working with routing and forwarding tables is the use of arithmetic operations in order to define the next hop toward a destination. Focusing on the proposed algorithms for small cage graphs, integer divisions and modular arithmetic are used, as well as assessing determined small values for node identifiers and distance.  
The aforementioned operations are usually implemented by a specific integrated circuit, which contains a number of logical gates. Additionally, the values to be operated are small; thus, the amount of bits is very low, thus reducing the overall number of necessary logical gates.  
Regarding performance, the hardware implementation makes a difference, as traditional routing and forwarding tables implement the matching operation through AND logical gates, which is supposed to be faster. However, the alternative proposed method based on the designed algorithms may be faster when it comes to small node identifiers, such as the ones used in the proposed topologies. For instance, Ref. [40] exhibits a layout with low power consumption when a small number of bits is involved. Conversely, Ref. [41]depicts a scheme to attain efficient lookup tables. Therefore, the hardware implementation and the design are key to establishing the most convenient method of packet forwarding.