N10-009-Section_2 Flashcards
Static Route
A static route is a fixed route that is manually configured and persistent. Can use less CPU/Memory resources cause there is no math being done to generate the routing table. Can also be more secure cause there are no routing protocols to analyze. Can be difficult to manage on larger networks.
Routers�
Filter and forward based on IP addresses. Interconnect network IDs. Routers don�t care where a packet came from, just where its going. Routers arent tied to Ethernet, they can have Dosis, Optical, all sorts of other connections
Routing Table
Table of info of connected network IDs and how to get to them
Default Route
If your router doesn�t know where to route data, it will send it up to its upstream router
Upstream Router
ISP’s router is called the upstream router
Metric (Routing)
Value that gives your router a route priority when there are equal options. Example: you have 2 uplinks from different ISPs, how does your router know which one will be the primary default route
Dynamic Routing
When routers automatically send routing tables to each other and converge on the best routs to different places
What is OSPF?
The main IGP - Open Shortest Path First - Uses Link State Protocols - Requires a single router to be the boss router (Elected Automatically, also elects a backup boss router). Uses Area IDs to designate the territory of each router (Area IDs are not IP address, although they look similar) OSPF can get to convergence faster than RIP. OSPF will choose the fastest link with the lowest cost. (For cost, see Link-State)
What is BGP?
Border Gateway Protocol - Hybrid protocol, has aspects of Distance Vector and Link State - Cornerstone of the Internet as it’s how ISPs talk with each other - BPG breaks the internet into ASes and routes data between them using the AS number.
EIGRP
EIGRP (Enhanced Interior Gateway Routing Protocol) is a dynamic routing protocol developed by Cisco, designed for use in IP networks to find the best path for data transmission. EIGRP is a hybrid routing protocol, combining aspects of both link-state and distance-vector protocols, and it is considered an advanced version of the older IGRP (Interior Gateway Routing Protocol).
What are the 2 kinds of routing methods Dynamic Routing Protocols use?
Distance Vector and Link State
What is Distance Vector?
One of the main types of Dynamic Routing Protocols Routing Methods, the grandfather. Where a router will send its entire routing table to all its neighbors for Convergence. Issues: Relies on hop count, sends routing table/info on an interval, so if something changes, it won’t update everyone else instantly. Example is RIP
What is Link State?
One of the main types of Dynamic Routing Protocols Routing Methods, the more modern one. Link state routers will check in with its neighboring routers every once in a while to see if anything has changed, it will also send updates as it detects changes (advertising). Example is OSPF. Each link has a “cost” that is based on the amount of throughput, reliability and round trip time and paths are chosen with this cost in mind.
What are the 2 kinds of routing scopes Dynamic Routing Protocols use?
IGP (Interior Gateway Protocols) and EGP (Exterior Gateway Protocols) - Protocols used to determine the most efficient path for data to travel between networks - This is a category of routing protocols, not a protocol itself
What is IGP?
IGP (Interior Gateway Protocol) - Used within a single AS - IGP Protocols can be Distance Vector or Link State - RIP, OSPF, EIGRP
What is EGP?
EGP (Exterior Gateway Protocol) - Used between different ASes - There is only 1 EGP and that is BGP (Border Gateway Protocol) Used by ISPs to talk with other ISPs
What is an AS?
Autonomous System - One organization that has control of their own routers - an ISP or a University
What is an ASN?
Autonomous System Number - Every AS is assigned a number (32-bit number) - this number is used in BGP to route information back and forth
What is RIP?
Routing Information Protocol - RIP is an IGP and a Distance Vector Protocol - RIP is where routers will exchange routing tables with each other to discover paths to other networks. RIP will use the hop count to determine the metric for each route. Max hops is 15. RIP can be slow cause there is a fixed interval for when it will exchange routing tables. RIP 2.0 can handle CIDR and has increased security
Convergence
Where all routing tables reflect all routes
Prefix Lenths in Routing
The most specific entry in the routing table “wins” as the best route. So the destination 192.168.1.6 is contained within the table entry of 192.168.0.0/16, but the entry 192.168.1.6/32 is more specific so that will be the entry chosen as the route. The higher the prefix (CIDR) the more specific the route.
Administrative Distances
What if you have two routing protocols and both know about a route to a subnet? Each routing protocol has a different metric calculation and you can’t compare metrics across routing protocols. Which one is do you trust the most? Each routing protocol within a router has an administrative distance and that determines which protocol has priority.
FHRP
FHRP stands for First Hop Redundancy Protocol. It’s a family of protocols used in networking to provide redundancy and high availability for the default gateway in a local network. FHRP ensures that if one gateway (usually a router) fails, another can take over immediately, minimizing downtime for connected devices. The backup router will detect that the main router is no longer online and will elect itself as the active router and take over the VIP.
Subinterfaces
Subinterfaces are virtual interfaces created on a physical network interface card (NIC) or port on network devices like routers or layer 3 switches. These subinterfaces allow a single physical interface to handle traffic for multiple VLANs (Virtual Local Area Networks) or different network segments, enabling inter-VLAN routing, IP address segmentation, and more efficient network management.
NAT Overload / PAT
PAT (Port Address Translation) is a form of Network Address Translation (NAT) that allows multiple devices on a private network to share a single public IP address when accessing external resources, such as the internet. PAT works by using different port numbers to distinguish between the different connections from devices on the internal network.
Trunking
A trunk port moves all VLAN traffic across switches. This is done by tagging the port
802.1Q
802.1Q is an IEEE standard that defines VLAN tagging for Ethernet frames, allowing multiple virtual LANs (VLANs) to coexist on a single physical network. It is commonly used in network switches to manage traffic across different segments of a network, isolating broadcast traffic and improving network security and efficiency.
Native vs Default VLAN
Default VLAN is the VLAN assigned to an interface by default, usually VLAN 1. a Native VLAN doesn�t add an 802.1Q header, can traverse a trunk.