CCNA 2 Chapter 4 - Routers
Routers are Computers
- It has a CPU, OS (Routers use Cisco IOS), Memory & Storage
Important Table - Router Components (of Memory)
- IP Routing &
- Packet Buffer
- Basic Diagnostic
- Limited IOS
Routers use specialized ports and network interface cards to interconnect to other networks.
Routers connect multiple networks.
Routers have multiple interfaces, each on a different IP network.
Default Gateway . Table entries are not packet-triggered like fast switching but change-triggered.Subnet Mask .Process Switching . .Routers use routing tables to determine the best path to send packets. .From DHCP Server. Device LEDs - Lights on the back of the router provide information if needed.Can be used in small networks with little amount of hosts.Identifies the host’s network subnet.Identifies unique host on local network.An older packet forwarding mechanism still available for Cisco router. fastest. > Default Gateways .Fast Switching . .TLDR “How to get out of the network”. > Packet Forwarding Methods .Cisco Express Forwarding (CEF) . .Routers encapsulates the packet and forwards it to the interface indicated in the routing table. Dynamically Assigned IP Address .The most recent.Manually assigned IP.Automatically obtained IP address.Used to identify specific network resources such as servers/printers.A common packet forwarding mechanism which uses a fast-switching cache to store next-hop information.Routers use static routes and dynamic routing protocols to learn about remote networks and build their routing tables. . . . . . and preferred Cisco IOS packet-forwarding mechanism.To enable network access devices must be configured with the following IP address information: .> Routers Choose Best Paths .IP Address . . .Most hosts acquire their IP address information through DHCP. > Enable IP on a Host - - > Statically Assigned IP Address .
Configure a global IPv6 Address with an Interface ID in the low order 64 bits. . telnet access. Terminal Emulation Software: TeraTerm/ PuTTY/ HyperTerminal.Secure Management Access .Use IPv6 address (link local / eui-64).Infrastructure devices require IP addresses. .It is important in the OSPF routing process.A loopback interface is a logical interface that is internal to the router. .A computer with proper software (see third item: terminal emu). and encrypted passwords. > Configure Basic Router Settings .Configure a specified global unicast address (addr/length). > Verify Interface Settings . . it is considered a software interface. > Configure IPv6 Router Interface .Configure a link-local address. Must use ‘no shutdown’. .Secure privileged exec. > Configure a Loopback Address . .A loopback interface is used for testing. Serial Cable using ‘DCE’ must have a clock rate.To Configure: . .show ip int brief . . > Configure IPv4 Router Interface .Show commands are used to verify operation and configuration of interface: .Distinguish the router’s name from other routers.show ip route .IPv6 supports more than one address.Activate using ‘no sh’.To Configure: - Configured with an IP & Subnet Address.It is not assigned to a physical port.Management IP addresses is assigned on a virtual interface. - Console Cable (RJ-45 to DB9 Console Cable). > Enabling IP on a Switch . .> Console Access - Console Access requires… . Provide a description. user exec.Name the Device . .
When a router has two or more paths to a destination with equal cost metrics.Diagram: .Open Shortest Path First (OSPF) . > Administrative Distance . the path installed in the routing table is the one with the lowest Administrative Distance (AD).Dynamic routing protocols use their own rules and metrics to build and update tables: .Can use parameters to filter: . . reliability.A static route with an AD of 1 is more reliable than an EIGRP discovered route with an AD of 90. exclude.- show running-config show interface … show ip interfaces - You can filter show commands. use the “|” pipe character. .Best path to a network is the path with the lowest network.Cost-based on cumulative bandwidth from source to destination. .Routing Information Protocol (RIP) . . .To filter out specific output of commands.section.Equal cost load balancing can be configured to use both dynamic routing protocol and static routes.Enhanced Interior Gateway Routing Protocol (EIGRP) Bandwidth. .A metric is the value used to measure the distance to a given network. > Load Balancing . .Hop Count . load. delay.Use the ‘terminal length <number>’ command to specify the number of lines to be displayed. then the router forwards the packets using both paths equally: .If multiple paths to a destination are configured on a router. . include. . .Equal cost load balancing can improve network performance.Best path is selected by a routing protocol based on the value or metric it uses to determine the distance of a network.A directly connected route with an AD of 0 is more reliable than a static route with an AD of 1. and begin > Best Path . .
.dynamic routing protocol . .Added to the routing table when an interface is configured.local route interfaces .- > > Routing Table Sources .Added when a route is manually configured and the exit interface is active.directly connected interfaces .show ip route . . .Display the contents of the routing table.Added to the routing table when an int is configured and active.static routes . Static Routes .Added when EIGRP or OSPF are implemented networks are identified.
.- Static routes and default static routes can be implemented after directly connected interfaces are added to the routing table. > Dynamic Routing - Where the routers “do the work for us”.
. EIGRP - OSPF - IS-IS - etc.Dynamic routing is used by routers to share information about the reachability and status of remote networks. It performs network discovery and maintains routing tables....