11/20/24, 10:23 AM
`
`What is routing? | IP routing | Cloudflare
`
`Log in
`
`What is routing? | IP routing
`
`On the Internet, routing is the way IP packets of data travel from their origin to their destination.
`
`Networking basics
`
`Copy article link
`
`What is routing?
`
`Network routing is the process of selecting a path across one or more networks. The principles of
`routing can apply to any type of network, from telephone networks to public transportation. In
`packet-switching networks, such as the Internet, routing selects the paths for Internet Protocol (IP)
`packets to travel from their origin to their destination. These Internet routing decisions are made
`by specialized pieces of network hardware called routers.
`
`Consider the image below. For a data packet to get from Computer A to Computer B, should it
`pass through networks 1, 3, and 5 or networks 2 and 4? The packet will take a shorter path
`through networks 2 and 4, but networks 1, 3, and 5 might be faster at forwarding packets than 2
`and 4. These are the kinds of choices network routers constantly make.
`
`https://www.cloudflare.com/learning/network-layer/what-is-routing/
`
`1/6
`
`PETITIONERS - AMERICAN/SOUTHWEST, Exhibit 1031
`Page 1 of 6
`
`

`

`11/20/24, 10:23 AM
`
`What is routing? | IP routing | Cloudflare
`
`Network 1
`
`Network 3
`
`Network 5
`
`Computer A
`
`Router
`
`Computer B
`
`Network 2
`
`Network 4
`
`How does routing work?
`
`Routers refer to internal routing tables to make decisions about how to route packets along
`network paths. A routing table records the paths that packets should take to reach every
`destination that the router is responsible for. Think of train timetables, which train passengers
`consult to decide which train to catch. Routing tables are like that, but for network paths rather
`than trains.
`
`Routers work in the following way: when a router receives a packet, it reads the headers* of the
`packet to see its intended destination, like the way a train conductor may check a passenger's
`tickets to determine which train they should go on. It then determines where to route the packet
`based on information in its routing tables.
`
`Routers do this millions of times a second with millions of packets. As a packet travels to its
`destination, it may be routed several times by different routers.
`
`Routing tables can either be static or dynamic. Static routing tables do not change. A network
`administrator manually sets up static routing tables. This essentially sets in stone the routes data
`packets take across the network, unless the administrator manually updates the tables.
`
`Dynamic routing tables update automatically. Dynamic routers use various routing protocols (see
`below) to determine the shortest and fastest paths. They also make this determination based on
`
`https://www.cloudflare.com/learning/network-layer/what-is-routing/
`
`2/6
`
`PETITIONERS - AMERICAN/SOUTHWEST, Exhibit 1031
`Page 2 of 6
`
`

`

`What is routing? | IP routing | Cloudflare
`11/20/24, 10:23 AM
`how long it takes packets to reach their destination — similar to the way Google Maps, Waze, and
`other GPS services determine the best driving routes based on past driving performance and
`current driving conditions.
`
`Dynamic routing requires more computing power, which is why smaller networks may rely on
`static routing. But for medium-sized and large networks, dynamic routing is much more efficient.
`
`★Packet headers are small bundles of data attached to packets that provide useful Information,
`including where the packet is coming from and where it is headed, like the packing slip stamped on
`the outside of a mail parcel.
`
`What are the main routing protocols?
`
`In networking, a protocol is a standardized way of formatting data so that any connected
`computer can understand the data. A routing protocol is a protocol used for identifying or
`announcing network paths.
`
`The following protocols help data packets find their way across the Internet:
`
`IP: The Internet Protocol (IP) specifies the origin and destination for each data packet. Routers
`inspect each packet's IP header to identify where to send them.
`
`BGP: The Border Gateway Protocol (BGP) routing protocol is used to announce which networks
`control which IP addresses, and which networks connect to each other. (The large networks that
`make these BGP announcements are called autonomous systems.) BGP is a dynamic routing
`protocol.
`
`The below protocols route packets within an AS:
`
`OSPF: The Open Shortest Path First (OSPF) protocol is commonly used by network routers to
`dynamically identify the fastest and shortest available routes for sending packets to their
`destination.
`
`RIP: The Routing Information Protocol (RIP) uses "hop count" to find the shortest path from one
`network to another, where "hop count" means number of routers a packet must pass through on
`the way. (When a packet goes from one network to another, this is known as a "hop.")
`
`Other interior routing protocols include EIGRP (the Enhanced Interior Gateway Routing Protocol,
`mainly for use with Cisco routers) and IS-IS (Intermediate System to Intermediate System).
`
`https://www.cloudflare.com/learning/network-layer/what-is-routing/
`
`3/6
`
`PETITIONERS - AMERICAN/SOUTHWEST, Exhibit 1031
`Page 3 of 6
`
`

`

`11/20/24, 10:23 AM
`
`What is routing? | IP routing | Cloudflare
`
`What is a router?
`
`A router is a piece of network hardware responsible for forwarding packets to their destinations.
`Routers connect to two or more IP networks or subnetworks and pass data packets between them
`as needed. Routers are used in homes and offices for setting up local network connections. More
`powerful routers operate all over the Internet, helping data packets reach their destinations.
`
`How does Cloudflare help make routing more
`efficient and secure?
`
`Cloudflare Argo uses smart routing to identify the fastest routes across the Internet, sending
`packets around highly congested networks rather than through them. The result is similar to when
`car traffic is routed around traffic jams: data packets arrive faster, accelerating the online
`experience for users.
`
`Cloudflare Magic Transit uses BGP to announce IP subnets on Cloudflare customers' behalf.
`Network traffic to those IP addresses is routed through the Cloudflare global network rather than
`going directly to those customers' networks. Cloudflare filters out any attack traffic before
`forwarding the legitimate traffic.
`
`RELATED CONTENT
`
`Network layer
`
`Local area network (LAN)
`
`What is a network switch?
`
`Internet Protocol (IP)
`
`What is MSS?
`
`Want to keep learning?
`
`Subscribe to theNET, Cloudflare's monthly recap of the Internet's most popular insights!
`
`https://www.cloudflare.com/learning/network-layer/what-is-routing/
`
`4/6
`
`PETITIONERS - AMERICAN/SOUTHWEST, Exhibit 1031
`Page 4 of 6
`
`

`

`11/20/24, 10:23 AM
`C
`
`Email: *
`
`v
`
`What is routing? | IP routing | Cloudflare
`
`\
`
`J
`
`Subscribe to theNET
`
`Refer to Cloudflare's Privacy Policy to learn how we collect and process your personal data.
`
`Getting Started
`
`Free plans
`
`For enterprises
`
`Compare plans
`
`Get a recommendation
`
`Request a demo
`
`Contact sales
`
`About the Network Layer
`
`Network Types
`
`Networking Basics
`
`Glossary
`
`Learning Center Navigation
`
`in O ©
`
`https://www.cloudflare.com/learning/network-layer/what-is-routing/
`
`5/6
`
`PETITIONERS - AMERICAN/SOUTHWEST, Exhibit 1031
`Page 5 of 6
`
`

`

`11/20/24, 10:23 AM
`What is routing? | IP routing | Cloudflare
`© 2024 Cloudflare, Inc. Privacy Policy Terms of Use Report Security Issues
`( Z D Your Privacy Choices
`| Trademark
`
`https://www.cloudflare.com/learning/network-layer/what-is-routing/
`
`6/6
`
`PETITIONERS - AMERICAN/SOUTHWEST, Exhibit 1031
`Page 6 of 6
`
`