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REDES - Coggle Diagram
REDES
IPv6 Packet Header
Version - This field contains a 4-bit binary value set to 0110 that identifies this as an IP version 6 packet.
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Flow Label - This 20-bit field suggests that all packets with the same flow label receive the same type of handling by routers.
Payload Length - This 16-bit field indicates the length of the data portion or payload of the IPv6 packet.
Next Header - This 8-bit field is equivalent to the IPv4 Protocol field. It indicates the data payload type that the packet is carrying, enabling the network layer to pass the data to the appropriate upper-layer protocol.
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The Network Layer
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De-encapsulation
When the packet arrives at the network layer of the destination host, the host checks the IP header of the packet.
If the destination IP address within the header matches its own IP address, the IP header is removed from the packet.
Router Memory
RAM - This is volatile memory used in Cisco routers to store applications, processes, and data needed to be executed by the CPU.
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NVRAM – This is non-volatile memory is used as the permanent storage for the startup configuration file (startup-config).
Flash - This non-volatile computer memory used as permanent storage for the IOS and other system related files such as log files, voice configuration files, HTML files, backup configurations, and more.
Limitations of IPv4
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Internet routing table expansion - A routing table is used by routers to make best path determinations. As the number of servers connected to the Internet increases, so too does the number of network routes.
Lack of end-to-end connectivity - Network Address Translation (NAT) is a technology commonly implemented within IPv4 networks. NAT provides a way for multiple devices to share a single public IPv4 address.
Introducing IPv6
Increased address space - IPv6 addresses are based on 128-bit hierarchical addressing as opposed to IPv4 with 32 bits.
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Eliminates the need for NAT - With such a large number of public IPv6 addresses, NAT between a private IPv4 address and a public IPv4 is not needed.
Host Forwarding Decision
Itself - A host can ping itself by sending a packet to a special IPv4 address of 127.0.0.1, which is referred to as the loopback interface. Pinging the loopback interface tests the TCP/IP protocol stack on the host.
Local host - This is a host on the same local network as the sending host. The hosts share the same network address.
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Host Routing Tables
Interface List - Lists the Media Access Control (MAC) address and assigned interface number of every network-capable interface on the host, including Ethernet, Wi-Fi, and Bluetooth adapters.
IPv4 Route Table - Lists all known IPv4 routes, including direct connections, local network, and local default routes.
IPv6 Route Table - Lists all known IPv6 routes, including direct connections, local network, and local default routes.
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A Router is a Computer
Branch - Teleworkers, small businesses, and medium-size branch sites. Includes Cisco Integrated Services Routers (ISR) G2 (2nd generation).
WAN - Large businesses, organizations, and enterprises. Includes the Cisco Catalyst Series Switches and the Cisco Aggregation Services Routers (ASR).
Service Provider - Large service providers. Includes Cisco ASR, Cisco CRS-3 Carrier Routing System, and 7600 Series routers.
Encapsulating IP
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The process of encapsulating data layer by layer enables the services at the different layers to develop and scale without affecting the other layers.
Routers can implement these different network layer protocols to operate concurrently over a network.
The routing performed by these intermediate devices only considers the contents of the network layer packet header.
Characteristics of IP
IP was designed as a protocol with low overhead. It provides only the functions that are necessary to deliver a packet from a source to a destination over an interconnected system of networks.
The protocol was not designed to track and manage the flow of packets. These functions, if required, are performed by other protocols at other layers, primarily TCP at Layer 4.
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Network Layer Protocols
- Internet Protocol version 4 (IPv4)
- Internet Protocol version 6 (IPv6)
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IP - Connectionless
IP is connectionless, meaning that no dedicated end-to-end connection is created before data is sent.
IP requires no initial exchange of control information to establish an end-to-end connection before packets are forwarded.
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IP - Media Independent
It is the responsibility of the OSI data link layer to take an IP packet and prepare it for transmission over the communications medium.
the maximum size of the PDU that each medium can transport. This characteristic is referred to as the maximum transmission unit (MTU).
The data link layer passes the MTU value up to the network layer. The network layer then determines how large packets can be.
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Default Gateway
The default gateway is the network device that can route traffic to other networks. It is the router that can route traffic out of the local network.
The host receives the IPv4 address of the default gateway either dynamically from Dynamic Host Configuration Protocol (DHCP) or configured manually.
A default route is the route or pathway your computer will take when it tries to contact a remote network.
