CS435 Lectures 7-12

•  Routing is a service of Network layer to find the best route.
•  Routing is performed by applying routing protocols and using the decision tables called routing tables in each router.
•  Forwarding is the action performed by a router on the basis of routing protocol and routing table according to the destination address of each packet received at any interface.
•  At network layer, each message from higher layer is broken down into packets.
•  A router performs packet switching.
•  Types of routing: o Unicast routing: A router forwards the packet to only one of the attached networks. o Multicast routing: A packet is forwarded to multiple attached networks.
•  Routing a packet from a source host to destination host can also be defined as routing a packet from a source router (the default router of the source host) to a destination router (the router connected to the destination network) through the intermediate routers using routing algorithms.
•  Types of routing: o Connectionless routing: All packets of the same message are treated independently and may or may not follow the same route. o Connection oriented routing: All the packets of same message are labeled and routed through a virtual circuit or a fixed route.
•  An internet can be considered as a graph with each network as an edge and each router as a node.
•  In a weighted graph, each edge has a weight or cost.
•  Least cost routing can be performed. Example algorithms: Distance-Vector routing, Link- State routing

Lesson No. 07 · ADVANCED TOPICS OF COMPUTER NETWORKS · Module No – 026: Broadband Networks & Internet:

•  All clouds are inherently dependent upon internetworking or Internet for ubiquitously remote provisioning of IT resources.
•  The cloud providers and consumers connect to Internet through ISPs.
•  The largest backbone networks of the Internet are strategically interconnected by core routers.
•  The core-routers connect the international networks.
•  The Internet has become a dynamic and complex aggregate of ISPs.
•  There is a hierarchical topology for worldwide interconnectivity composed of tiers.
•  There are three tiers of worldwide connectivity: o Tier 1 consists of large-scale international connectivity providers. o Tier 2 consists of large regional ISPs connected to tier 1. o Tier 3 consists of local ISP providers connected to tier 2.
•  The cloud providers and users connect directly to tier 3 providers.

Module No – 027: Internet Architecture & Cloud Deployment:

•  Internet supports the remote provisioning of IT resources.
•  Cloud relies heavily upon Internet.
•  The connectivity of end-users of cloud depends upon how the centralized resources of cloud are deployed.
•  The cloud resources deployment can be either on-premises or Internet based.
•  In cloud deployment using the on-premises, the provider sets up a fully controlled corporate network and a corporate Internet connection for the deployment of IT solutions and applications.
•  In the on-premises deployment, the internal users access the cloud through corporate network. The remote users connect through internet by using virtual private network (VPN).
•  A VPN creates a secure connection between a remote device and the corporate servers over the internet as if the device is inside the LAN.
•  For the internet based deployment, the cloud provider has an Internet connection and al the internal and external users access the cloud resources through cloud provider’s internet connection.
•  In this deployment, there is an extra charge for internet connectivity.

Module No – 028: Scalable Computing over Internet:

•  Scalable computing may refer to the dynamic resizing of the available computing resources (processing, memory, bandwidth, storage etc.) with demand.
•  The growth of users and user demands for scalable computing over internet has been accompanied with matching growth in network, computing and resource management technologies.
•  The computing platforms have evolved as follows o Mainframes (1950-70) o Minicomputers (1960-1980) o Personal computers (1970-1990) o Portable computers (1980-2000)
•  Since 1990, the High Performance Computing (HPC) and High Throughput Computing (HTC) have been relying upon clusters, grids and the Internet clouds.
•  The speed for HPC systems (supercomputers) has increased from Gflops in early 1990s to now Pflops in 2010.
•  The network bandwidth has been doubling each year in the recent past (Gilder’s law).
•  Processor speed has been doubling every 18 months (Moore’s law).
•  Means that there has been a steady growth in these technologies.
•  Fine grain (instruction level) parallelism and coarse grain (job level) parallelism are available.
•  Ubiquitous computing is what refers to computing at any place and time using pervasive devices and wired or wireless communications.
•  Utility computing works upon a business model in which the customers pay for computational resources from a provider.
•  Cloud computing provides ubiquitous utility computing.

Module No – 029: Technologies for Network based Systems:

•  The processor speed and network bandwidth have shown a remarkable growth in last few decades.
•  The processor clock rate has risen from 10 MHz in 1970s to over 4GHz in 2010s.
•  The network band has increased from 10 Mbps to over 100,000 Mbps
•  The excessive heat generation from single processor core with high frequency has limited the maximum speed unless the chip technology matured.
•  This has lead to the multi-core architecture of CPUs with dual, quad, six or more cores.
•  The graphical processing unit (GPU) development has adopted a many-core architecture with hundreds to thousands of cores.
•  Modern architecture of CPUs and GPUs have enhanced the instruction level parallelism (ILP) and the volume of millions of instructions per second (MIPS).
•  Sun’s Niagara CPU can provide 64 count for ILP.
•  Intel’s Core i7 990x can provide 159,000 MIPS execution rate
•  The CPUs and GPUs are multithreaded, which means that each core can execute multiple processes or threads concurrently.
•  A GPU unit has far more (but slower) cores than a multi-core CPU
•  The DRAM memory chip capacity has increased from 16 KB in 1976 to 64 GB in 2011.
•  The hard disk capacity has increased from 260 MB in 1981 to 3TB a few years ago.
•  The flash memory and solid-state drives are rapidly evolving.
•  Disk arrays are being utilized to enhance the storage.
•  Servers can be connected to network storage such as disk arrays through storage area network (SAN)
•  A disk array can be connected to client hosts through network attached storage (NAS)
•  The high bandwidth networks in WAN scope can connect the host computers to network storage.
•  A single host can be shared among multiple instances of operating systems through virtualization technology. More on this latter.

Module No – 030: Web 2.0

•  It is the second generation of world wide web.
•  Lets people collaborate and share comments, media and information online.
•  The web pages progressed from static to dynamic and interactive.