The third element in the M40 is the Control Plane. Modern high-capacity routers still use highly optimized ASIC forwarding planes, but capacity for a single router can easily run to several Terabits/sec (i.e., several thousand Gb/s). With a maximum capacity of over 40 Gbit/s, the M40 forwarding plane is capable of forwarding 40 million packets each second. The M40 router’s forwarding plane actually does a number of additional functions to manage network overload, or to implement security policies, but the key idea is that the forwarding plane does all the work to get packets from any input to any output, and is carefully optimized to do it quickly. The forwarding plane’s job is to receive each packet one at a time from the interface modules, look up the packet’s destination address in a route table, and then send it to the proper outbound interface. Inside the router, there’s a Forwarding Plane, which is where the high-speed custom silicon devices that move each packet are found. The M40 router is modular, which means that small interface modules called PICs can be plugged in, providing connections to many different kinds of copper or optical fiber transmission media, such as Ethernet, FDDI, or a telco favorite, SONET/SDH. The most obvious router component would be its External Interfaces. The Juniper M40 router, and most high-performance Internet routers since, are built from several key functions. These are modest numbers by today’s standards, but it was a game-changer in 1998, enabling the growth of the Internet that continues today. The result was a huge increase in router capacity, from a few Gbit/s to tens of Gbit/s for a single router.
#Internet backbone software#
This formed the basis of the Juniper M40 router, the first commercially-successful product to use specialized ASIC technology to forward packets from the router’s incoming to outgoing interfaces without being slowed by software intervention.
Recognizing that even routers made of many general-purpose computers weren’t going to be fast enough, the founders of Juniper Networks took advantage of the growing capability of customized silicon chips called Application Specific Integrated Circuits (ASICs) to make special-purpose hardware that could perform the key elements of the router’s function much faster than ordinary microprocessors. All functions – looking up packet addresses, shuffling packets from incoming to outgoing interfaces, as well as computing routing tables – were done by carefully-written software running in the router.īut the amount of traffic passing through routers grew rapidly in the early 1990s, to the extent that ordinary computers just couldn’t keep up. Routers have been fundamental building blocks since the invention of the Internet, but early routers were simply computers with network interfaces running specialized software. Looking up an IP address in a table isn’t so hard to do, but the list of possible destinations (called ‘routes’) in the Internet is large (currently over half a million), and it has to be done very quickly – a single Gigabit Ethernet interface can deliver 1.4 million small packets every second, each potentially with a different destination. Multiply that by millions of people using the Internet, and there are a lot of packets to be sent!Īs a traffic exchange point, the key function of the router is to look at the IP address in each packet and forward the packet to another router that might be closer to the ultimate destination (e.g., your laptop!), a process called forwarding.
#Internet backbone movie#
Needless to say, when only a few hundred words will fit in each packet, it takes many packets to transmit even a simple web page, let alone a movie or phone call.
#Internet backbone series#
Internet traffic, such as a web-page download, is sent as a series of packets, each of which contains an Internet Protocol (IP) address to show where it’s going, and some data (usually no more than 1500 bytes). The resulting web of connections can get traffic from any place to any other place by hopping from one router to the next. At each point in the network where several fiber optic links come together, the network designers place a router, which acts as a traffic exchange.
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