I did look at Wikipedia sites but I'm still unsure about the definitions of the three. This is what happens at IP routers shortest prefix routing. An exact match tells the switch at which port to output the packet without further computation or decisions to be made. If no match is found, a default action is performed or a seperate controller is asked as in SDN.
This cna be done faster than routing because of less computation and specialized hardware, correct? Switching seems to be fairly similar to forwarding but with an emphasis on what happens on hardware in the switching fabric after the lookup in a table. This on OSI level 2 data link while routing and forwarding are actions on level 3 network?
Did I miss something of importance? What about the MAC layer? In general, forwarding refers to a device sending a datagram to the next device in the path to the destination, switching refers to moving a datagram from one interface to another within a device, and routing refers to the process a layer-3 device uses to decide on what to do with a layer-3 packet.
A host sending data to another host through an ethernet interface will place a frame on the wire. If the next device is a bridge a switch is a bridge , the bridge will inspect the frame for the source and destination MAC addresses. The bridge will use the source MAC address in its MAC address table so that it knows the host with that MAC address is connected to the interface where the frame entered the bridge.
It will also try to look up the destination MAC address in its MAC address table to see to which interface it should switch the frame. If it finds the MAC address in its MAC address table, it will switch the frame to the interface indicated in its MAC address table, otherwise it will flood the frame to all other interfaces, forwarding the frame to the device s on the other end s of the interface s link s.
A router receiving a frame on an interface will strip the frame from the packet. The router will then try to look up the destination IP address in its routing table. If it doesn't find a match, even a default route, it will drop the packet. If it finds one or more matches, it will switch the packet to the interface of the longest match in the routing table.
The router will then prepare a new frame for the packet on the new interface the link on new interface may or may not use MAC addresses , and the router will forward the new frame containing the original packet over the next hop interface toward its destination. The whole process a router uses is called routing , but within the router, it switches packets before forwarding them to the next hop device.
The way I see it, forwarding applies to forwarding at any layer. Routing describes this function when the forwarding decision is made at layer 3, using the IP destination address. Switching and bridging refer to the forwarding decision being made at layer 2, using the destination MAC address. I know there is some confusion around this as I have seen layer 3 forwarding referred to as switching when it is carried out on an L3 switch.
The term forwarding is used to describe moving any protocol across the network, and it decides which exit interface to use to send the packet to its next hop. Routing is the process of forwarding packets at L3 of the OSI model. Administering Network Interfaces Tasks. Configuring an IPv6 Network Tasks. Troubleshooting Network Problems Tasks. IP Security Architecture Overview. IP Security Architecture Reference.
Administering Mobile IP Tasks. This section contains procedures and examples that show how to configure forwarding and routing for routers and hosts on IPv4 networks.
Packet forwarding is the basic method for sharing information across systems on a network. Packets are transferred between a source interface and a destination interface, usually on two different systems. When you issue a command or send a message to a nonlocal interface, your system forwards those packets onto the local network. The interface with the destination IP address that is specified in the packet headers then retrieves the packets from the local network. If the destination address is not on the local network, the packets are then forwarded to the next adjacent network, or hop.
By default, packet forwarding is automatically configured when you install Oracle Solaris. Routing is the process by which systems decide where to send a packet. When the source system and the destination system are on the same local network, the path that packets travel between them is called a direct route.
If a packet must travel at least one hop beyond its source system, the path between the source system and destination system is called an indirect route. The routing protocols learn the path to a destination interface and retain data about known routes in the system's routing table.
Routers are specially configured systems with multiple physical interfaces that connect the router to more than one local network. Therefore, the router can forward packets beyond the home LAN, regardless of whether the router runs a routing protocol. For more information about how routers forward packets, refer to Planning for Routers on Your Network. Routing protocols handle routing activity on a system and, by exchanging routing information with other hosts, maintain known routes to remote networks.
Both routers and hosts can run routing protocols. The routing protocols on the host communicate with routing daemons on other routers and hosts. These protocols assist the host in determining where to forward packets. When network interfaces are enabled, the system automatically communicates with the routing daemons. These daemons monitor routers on the network and advertise the routers' addresses to the hosts on the local network. Some routing protocols, though not all, also maintain statistics that you can use to measure routing performance.
Unlike packet forwarding, you must explicitly configure routing on an Oracle Solaris system. This section contains tasks for administering packet forwarding and routing on IPv4 routers and hosts. Routing protocols are classified as interior gateway protocols IGPs , exterior gateway protocols EGPs , or a combination of both.
Interior gateway protocols exchange routing information between routers on networks under common administrative control. In the network topology shown in Figure , the routers run an IGP for exchanging routing information. Exterior gateway protocols enable the router that connects the local internetwork to an external network to exchange information with another router on the external network.
The following table provides information about the Oracle Solaris routing protocols and the location of each protocol's associated documentation. Oracle Solaris also supports the Open Source Quagga routing protocol suite.
These protocols are available from the SFW consolidation disk, though they are not part of the mainOracle Solaris distribution. The following table lists the Quagga protocols:. The figure shows a corporate network autonomous system that is subdivided into two routing domains, A and B.
A routing domain is an internetwork with a cohesive routing policy, either for administrative purposes or because the domain uses a single routing protocol. Both domains in the figure run routing protocols from the Quagga protocol suite. All systems within this domain run OSPF as their interior gateway protocol. In addition to internal hosts and routers, Domain A includes two border routers. To facilitate communications between the Corporate Network and the outside world, R1 runs BGP over its externally facing network interface.
For more information on the Quagga protocols, refer to the Open Solaris Quagga. For configuration procedures for these protocols, go to the documentation for quagga. Sites with multiple routers and networks typically administer their network topology as a single routing domain, or autonomous system AS. The following figure shows a typical network topology that would be considered a small AS. This topology is referenced in the examples throughout this section.
The figure shows an AS that is divided into three local networks, Four routers share packet-forwarding and routing responsibilities. The AS includes the following types of systems:. Border routers connect an AS to an external network, such as the Internet.
In Figure , the border router's interfaces connect to internal network Default routers maintain routing information about all the systems on the local network. In Figure , Router 1s interfaces are connected to internal network Router 1 also serves as the default router for Router 1 maintains routing information for all systems on Router 2s interfaces connect to internal network Packet-forwarding routers forward packets but do not run routing protocols.
This type of router receives packets from one of its interfaces that is connected to a single network. These packets are then forwarded through another interface on the router to another local network. In Figure , Router 3 is a packet-forwarding router with connections to networks Multihomed hosts have two or more interfaces that are connected to the same network segment.
A multihomed host can forward packets, which is the default for all systems that run Oracle Solaris. Figure shows a multihomed host with both interfaces connected to network For an example of configuring a multihomed host, refer to Example Single interface hosts rely on the local routers, not only for packet forwarding but also for receiving valuable configuration information.
Figure includes Host A on the This section contains a procedure and example for configuring an IPv4 router. Because a router provides the interface between two or more networks, you must assign a unique name and IP address to each of the router's physical network interfaces. Thus, each router has a host name and an IP address that are associated with its primary network interface, in addition to a minimum of one more unique name and IP address for each additional network interface.
You can also use the following procedure to configure a system with only one physical interface by default, a host to be a router.
Note - You can configure all interfaces of a router during Oracle Solaris system installation. The following instructions assume that you are configuring interfaces for the router after installation. Previous Python - Tuple to Dictionary Summation conversion. Recommended Articles. Article Contributed By :. Easy Normal Medium Hard Expert.
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