CompTIA Chapter 5 Topic A... Explain Characteristics of Routing

Interior Gateway Routing Protocol (IGRP)

Provides a routing protocol for routing within a domain or autonomous system.

Routing algorithm metrics - MTU (Maximum transmission unit)

How large a packet can be sent without the need for fragmentation

Derive the network ID

Masking the full IP address against a network prefix or subnet mask

The maximum hop count is (To prevent looping)

15

Routing algorithm metrics - Load

A metric that bases routing decisions on how busy a route is

Black hole

A packet is discarded without notificiation back to the source

Metric

A preference balue assigned to the route, with low values being preferred over high ones. The value of the metric may be determined by different parameters.

Learned route

A route that was communicated to the router by another router by using dynamic routing protocol

route aggregation

A supernet configuration implemented for the purpose of reducing the number of routing table entries by combining several entries, one for each network, into one entry that represents multiple networks.

Distance vector

Algorithms require that routers periodically propagate their entire routing table to their immediate neighbors.

Classless Inter-Domain Routing (CIDR)

Allows network administrators to expand the number of network nodes assigned to an IP address.

Open shortest path first (OSPF)

An interior gateway routing protocol developed for IP networks based on the shortest path first or link-state algorithm.

BGP port

BGP works over TCP on port 179

Backbone (Area 0)

Created by the collection of border routers.

Routing table entries category

Default routes, which are used when a better network or host route is not found.

Switches

Devices communicate with different network segments through these. They are limited to hosts within the same broadcast domain (link-local)

Routing table entries category

Direct network routes, for subnets to which the router is directly attached

Modern routers use

Dynamic Routing Protocol

Enhanced Interior Gateway Routing Protocol (EIGRP)

Enhanced version or IGRP which allows classless addressing, replaced IGRP making IGRP obsolete

Routing algorithm

Formula that is stored in the router's memory. Makes decisions for the router concerning the best path for data.

Routing table entries category

Host routes, for routes to a specific IP address

End systems (ESs)

Hosts with no capcity to forward packets to other IP networks are refferred to as

Routing Table

Information about the location of other IP networks and hosts is stored in this.

Routing algorithm metrics - Latency

It takes time for a packet to traverse an internetwork. Delay-based metrics measure transit time. This metric is most important if the route is used to carry time-sensitive data, such as voice or video

Dynamic Routing Protocol

Learn about remote networks and the most efficient route to these networks.

Static routing

Means that you manually add routes to a routing table, and they change only if you edit them. Configuring static routing entries can be useful in some circumstances, but it can be problematic if the routing topology changes often, as each route on each affected router needs to updated manually.

IP datagram (89)

Messages sent using OSPf's own datagram format

Routing algorithm metrics - Bandwidth

Metrics based on bandwidth look at the maximum achievable bandwidth on a link and do not consider the available bandwidth. This is a less efficient metric than delay-based metrics

Steady state

Network where all the routers share the same topology

Routing algorithm metrics - Reliability

Over time, it might become obvious that some links between routers are more reliable than others. You can assign a value for this reliability that routers can assess when determining an effective path

OSPF also supports

Plain text or cryptographic authentication

Ases

RFC 1930

Routing table entries category

Remote network routes, for subnets and IP networks that are not directly attached

Area borer routers

Routers that can connect to multiple areas

Intermediate systems (ISs)

Routers that interconnect IP networks and can perform this packet forwarding process are known as

Destination IP address and netmask

Routes can be defined to specific hosts but are more generally directed to network IDs

Flood broadcast traffic

Switches

Routing

Takes place when a host needs to communicate with a host on a different IP network or a different subnet

Rip considers only one route to a given destination network

That with the lowest HOP count

Gateway/next hop

The IP address of the next router along the path

Routing algorithm metrics - Path length

The end-to-end cost of using a route(hop count). You might assign a value to a path between router A and B and between B and C. The end-to-end path length is the sum of A-to-B and B-to-C

Interface

The local port to use to forward a packet along the chosen route

Prefixes are allocated in a hierarchical manner

The smaller prefix blocks, which contain more networks, going to internet registries, who then allocate mid-size blocks to ISPs who then allocate the blocks with the largest network prefixes to end users.

0.0.0.0/0

This is the all 0s default route. if a packet's destination address does not match any of the other entries, this is the route that will be used. The gateway for the route is Router A

192.168.1.255/32

This is the broadcast address for the 192.168.1.0/24 IP network

192.168.1.22/32

This is the host's own address, so any traffic for it, is directed ot the loopback itnerface

127.0.0.1/8

This is the loop back address for directing any communications back to the same host. This is used mostly for toubleshooting

192.168.1.0/24

This represents the host's local IP network, so it uses its 192.168.1.22 interfaces as the gateway to deliver packets to hosts on the same subnet, resolving IP addresses to MAC addresses by using ARP

BGP

Type of exterior gateway protocol

link-state advertisement (LSA)

Used to update a routing table. "Advertise" what routers they know of

RIP uses the what?

User Datagram Protocol (UDP port 520)

Riping(IPv6)

Uses UDP port 521

Early routers

Were manually configured with routing information.

Packet delivery

When a router receives a packet, it goes through the same process that the source host did to calculate if the packet needs to be routed to another router or it can be delivered locally to another interface(Directly connected route)

Routing algorithm metrics (Price/costs)

You can assign a monetary cost to various links, and the router using a cost metric will try to select the cheapest link available. This is useful for organizations routing on a budget.

High level network routing prefixes (CIDR blocks), /8

are allocated by the IANA to RIR, such as ARIN and RIPE. Few are held by private companies such as IBM, HP, AT&T

Routing Information Protocol (RIP)

is a long-established distance vector-based routing protocol. It uses a hop count metric to determine the distance to the destination network.

All IP hosts are capable of functioning as routers

but most workstation and server computers are configured with a single network adapter connected to only one network.

Loop

causes a packet to be forwarded around the network until its TTL(Time to live) expires

Border Gateway Protocol(BGP)

designed to be used between routing domains, or Autonomous Systems (ASes)

Routers (Interconnect)

desinged to connect inner networks and support connectivity to distant networks. 1. They use a routing table to determine the next hop interface to use to forward a packet 2. They can connect dissimilar layer 2 network segments. This strips the layer 2 header of an incoming packet and replaces it with the appropriate layer 2 header for the destination interface.

Classless IPv4 routing uses a mix of

flat and hierarchical structures to make more efficient use of the limited address space compared tot he old method of classful address allocation

EIGRP

is a native IP protocol, which means that it is encapsulated directly in IP datagrams, rather than using TCP or UDP.

Router Interface

is a seperate broadcast domain. Routers do not typically forward broadcast traffic, though this can be overridden vy config specific router setting (DHCP relay)

IPv6 interface

is always 64 bits

Interior gateway protocol (IGP)

is one that performs routing within a network under the administrative control of a single owner (Autonomous system (AS)

IPv6 network prefix

is only given in slash notation

Convergence

is the process whereby routers running dynamic routing algorithms agree on routes through the internetwork

Ethernet switches

make forwarding decisions based on layer 2 MAC addresses

Routers

make forwarding decisions based on layer 3 network addresses. These are typically IP addresses.

Exterior gateway protocol (EGP)

one that can perform routing between autonomous ystems.

Next hop

the destination router indicated by the outgoing interface entry in the routing table

In IPv4 the network prefix can be increased

to make more network numbers available(At the expense of the number of host IDs left available for each network.