ccna 640-802 pdf 7th edition

ccna 640-802 pdf 7th edition.6.2.1.2 Cache OverflowLayer 2 LAN switches perform switching and filtering based only on the MAC address of the OSI Data Link Layer (Layer 2). The switch is completely transparent to the network protocol and user applications. The Layer 2 switch constructs a MAC address table and uses it to make outgoing forwarding decisions. The switch analyzes part or all of a packet against the MAC address table before forwarding the packet to the destination host.The Ethernet switch may use caching techniques to store data frames before forwarding them. Caching techniques may also be used when the destination port is busy due to congestion. In this example, the switch stores the data frame before it can send it. Therefore, a fundamental security consideration for switches is cache overflow. A cache overflow vulnerability can overwrite an application's memory by writing data to an area outside of the allocated cache. In the case of switches, cache overflows typically manifest themselves in the form of MAC address table overflows due to MAC address table overflow attacks. Cache overflows often originate from DoS attacks. Cache overflows can be used to execute arbitrary code in an application and perform unauthorized elevation of privileges.In today's Internet, cache overflows are probably one of the most common methods used to compromise applications. They are mainly used to gain access to root privileges or to cause DoS attacks. There are several different tools available to prevent cache overflows.6.2.2 MAC Address Spoofing Attacks6.2.2.1 Switch MAC Address TablesA switch manages the flow of data between end IIs by creating an instantnetwork, and this network contains only two end devices that communicate with each other at the same .Two end devices that communicate with each other at the same time. The switch forwards data to the specified port based on the MAC address to achieve the above II's. The switchmaintains a MAC address table, also known as a content addressable memory (CAM) collocation table, to keep track of the source MAC address associated with each switch portsource MAC address associated with each switch port. These interrogation tables are populated through the address learning process on the switch.