Networking Basics
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Networking: Network Layer
CS 4410 Operating Systems Networking: Network Layer Summer 2013 Cornell University 1 Today ● How packages are exchanged in a WAN? ● Network Layer ● IP ● Naming ● Subnetwork ● Forwarding ● Routing Algorithms 2 Protocol Stack Computer A Computer B Message M Application Application Segment Ht M Transport Transport Datagram Hn Ht M Network Network Frame Hl Hn Ht M Link Link Physical Physical 3 WAN ● Usually, thousands of computers need to be interconnected. ● The capabilities that LANs offer cannot support larger networks. ● We need more services than the Link Layer offers. ● Why? ● Clever Naming ● Efficient forwarding/routing of messages. 4 Network Layer ● Mission: Transfer messages from the source-computer to the destination- computer. ● Attention: this is different from the mission of the Link Layer. ● Services: ● Forwarding / Routing ● Guaranteed delivery, bandwidth, etc ● Security ● Not all the protocols support these services. ● The Network Layer protocol depends on the kind of network we want to built: ● Virtual-circuit networks ● Datagram networks ● Necessary network device: ● Router: It knows where to forward the message. 5 Network Layer ● Virtual-circuit networks ● 3 phases ● Establish a virtual circuit. – The Network Layer finds the path from the source to the destination. – Reserve resources for the virtual circuit. ● Transfer data – Packets pass through the virtual circuit. ● Destroy virtual circuit. – Release resources. ● Disadvantages? ● Datagram networks ● Every packet has the destination address and it is routed independently in the network. ● The router uses the destination address to forward the packet towards 6 the destination-computer. IP ● Network Layer Protocol for the Internet: ● Internet Protocol ● For Datagram networks. ● IPv4, IPv6 ● Datagram structure: Version Header Type of Length Length service Identification Flags Fragment Offset Time to live Protocol Header Checksum Source IP Address (32-bit) Destination IP Address Options Data 7 Naming ● All the computers in the Internet have one or more IP addresses. -
Rudiments of Routing
Rudiments of Routing Moving bits from the source to the destination is a major function of computer networking. On the current Internet, the Network layer is responsible for achieving this. AS 2 AS 1 Inter-domain routing OSPF and RIP Inter-domain routing OSPF and RIP Intra-domain routing BGP In general, most routing within Autonomous Systems use Routing Information Protocol (RIP), or its enhanced version Open Shortest Path First (OSPF). The current de facto Intra-domain routing standard is Border Gateway Protocol(BGP), Version 4. You need to concern yourself with these protocols if you are dealing with routers inside or between Autonomous Systems. At the host level, however, most likely you need only a static routing table. This is a table of routes that the OS kernel keeps. It is possible to add to and delete from routes in the kernel routing table relatively easily. We discuss routing tables based on RIP (RFC2453). When looking at routing tables, remember that most Unix-like operating systems use mnemonic names for their interfaces. For example, in Linux, the Ethernet interfaces on a machine are called eth0, eth1, eth2, etc. On the newer SUN/Solaris machines the interfaces are named eri0, eri1, etc. PPP interfaces are usually names ppp0, ppp1 etc. You can see all the configured interfaces on a host using the ifconfig command which is usually found in /sbin/ directory (but not always). You can see the routing table with ªnetstat -rº command. Here©s a screen shot of these commands run on matrix.newpaltz.edu which is a SUN/Solaris machine: The output from /sbin/ifconfig command shows that there are two configured interfaces, one an Ethernet and the other the loopback interface. -
Internet Routing Over Large Public Data Networks Using Shortcuts
Internet Routing over Large Public Data Networks using Shortcuts Paul F, Tsuchiya, Bellcore, [email protected] When a system (a router or host) needs to send an internet packet, it must determine the destination subnetwork Abstract address to send the packet to. (IP systems traditionally do this as a two-step process. First the 1P address of the With the emergence of large switched public data networks receiving system is determined. Then the subnetwork that are well-suited to connectionless internets, for instance address associated with the 1P address is derived.) On SMDS, it is possible that larger and larger numbers of broadcast LANs this has proven to be relatively simple. internet users will get their connectivity from large public This is because 1) broadcast LANs have a small number of data networks whose native protocols are not the same as attached systems (hundreds), and 2) broadcast LANs have the user’s internet protocol. This results in a routing an inexpensive multicast, thus making “searching” for problem that has not yet been addressed. That is, large systems on a LAN inexpensive and easy. numbers of routers (potentially tens of thousands) must be able to find direct routes to each other in a robust and On very large general topology subnetworks (called here efficient way. This paper describes a solution to the public data networks, or PDNs2), however, determining problem, called shortcut routing, that incorporates 1) a “next hop” subnetwork (or PDN) addresses is not sparse graph of logical connectivity between routers, 2) necessarily simple. There may be (eventually) tens of hierarchical addressing among the public data network thousands of systems attached to a PDN, making it subscribers, and 3) the use of “entry router” information in inefficient to distribute up-to-date information about all packets to allow routers to find one hop “shortcuts” across systems to all systems. -
2-Atn-Bgp-Pdf
A Simple BGP-Based Routing Service for the Aeronautical Telecommunications Network (with AERO and OMNI) IETF 111 rtgwg session (July 28, 2021) Fred L. Templin (The Boeing Company) [email protected] [email protected] 1 Document Status • “A Simple BGP-based Mobile Routing System for the Aeronautical Telecommunications Network” • BGP-based “spanning tree” configured over one or more Internetworking “segments” based on Non-Broadcast, Multiple Access (NBMA) interface model and IPv6 Unique Local Address (ULA) prefixes • ASBRs of each segment in a “hub-and-spokes” arrangement, with peering between adjacent segment hubs • IETF rtgwg working group item since August 30, 2018 - coordinated with International Civil Aviation Organization (ICAO) Aeronautical Telecommunications Network (ATN) • https://datatracker.ietf.org/doc/draft-ietf-rtgwg-atn-bgp/ • Work ready for IETF rtgwg WGLC • “Automatic Extended Route Optimization (AERO)” • Route optimization extensions that establish “shortcuts” to avoid strict spanning tree paths • Mobility/multilink/multinet/multihop support based on agile “hub-and-spokes” ClientProxy/Server model • https://datatracker.ietf.org/doc/draft-templin-6man-aero/ • Work ready for IETF adoption • “Transmission of IP Packets over Overlay Multilink Network (OMNI) Interfaces” • Single NBMA network interface exposed to the IP layer with fixed 9KB MTU, but configured as an overlay over multiple underlying (physical or virtual) interfaces with heterogeneous MTUs • OMNI Adaptation Layer (OAL) – minimal mid-layer encapsulation that -
Ipv6 Addresses
56982_CH04II 12/12/97 3:34 PM Page 57 CHAPTER 44 IPv6 Addresses As we already saw in Chapter 1 (Section 1.2.1), the main innovation of IPv6 addresses lies in their size: 128 bits! With 128 bits, 2128 addresses are available, which is ap- proximately 1038 addresses or, more exactly, 340.282.366.920.938.463.463.374.607.431.768.211.456 addresses1. If we estimate that the earth’s surface is 511.263.971.197.990 square meters, the result is that 655.570.793.348.866.943.898.599 IPv6 addresses will be available for each square meter of earth’s surface—a number that would be sufficient considering future colo- nization of other celestial bodies! On this subject, we suggest that people seeking good hu- mor read RFC 1607, “A View From The 21st Century,” 2 which presents a “retrospective” analysis written between 2020 and 2023 on choices made by the IPv6 protocol de- signers. 56982_CH04II 12/12/97 3:34 PM Page 58 58 Chapter Four 4.1 The Addressing Space IPv6 designers decided to subdivide the IPv6 addressing space on the ba- sis of the value assumed by leading bits in the address; the variable-length field comprising these leading bits is called the Format Prefix (FP)3. The allocation scheme adopted is shown in Table 4-1. Table 4-1 Allocation Prefix (binary) Fraction of Address Space Allocation of the Reserved 0000 0000 1/256 IPv6 addressing space Unassigned 0000 0001 1/256 Reserved for NSAP 0000 001 1/128 addresses Reserved for IPX 0000 010 1/128 addresses Unassigned 0000 011 1/128 Unassigned 0000 1 1/32 Unassigned 0001 1/16 Aggregatable global 001 -
Command-Line IP Utilities This Document Lists Windows Command-Line Utilities That You Can Use to Obtain TCP/IP Configuration Information and Test IP Connectivity
Guide to TCP/IP: IPv6 and IPv4, 5th Edition, ISBN 978-13059-4695-8 Command-Line IP Utilities This document lists Windows command-line utilities that you can use to obtain TCP/IP configuration information and test IP connectivity. Command parameters and uses are listed for the following utilities in Tables 1 through 9: ■ Arp ■ Ipconfig ■ Netsh ■ Netstat ■ Pathping ■ Ping ■ Route ■ Tracert ARP The Arp utility reads and manipulates local ARP tables (data link address-to-IP address tables). Syntax arp -s inet_addr eth_addr [if_addr] arp -d inet_addr [if_addr] arp -a [inet_address] [-N if_addr] [-v] Table 1 ARP command parameters and uses Parameter Description -a or -g Displays current entries in the ARP cache. If inet_addr is specified, the IP and data link address of the specified computer appear. If more than one network interface uses ARP, entries for each ARP table appear. inet_addr Specifies an Internet address. -N if_addr Displays the ARP entries for the network interface specified by if_addr. -v Displays the ARP entries in verbose mode. -d Deletes the host specified by inet_addr. -s Adds the host and associates the Internet address inet_addr with the data link address eth_addr. The physical address is given as six hexadecimal bytes separated by hyphens. The entry is permanent. eth_addr Specifies physical address. if_addr If present, this specifies the Internet address of the interface whose address translation table should be modified. If not present, the first applicable interface will be used. Pyles, Carrell, and Tittel 1 Guide to TCP/IP: IPv6 and IPv4, 5th Edition, ISBN 978-13059-4695-8 IPCONFIG The Ipconfig utility displays and modifies IP address configuration information. -
Lab 5.5.2: Examining a Route
Lab 5.5.2: Examining a Route Topology Diagram Addressing Table Device Interface IP Address Subnet Mask Default Gateway S0/0/0 10.10.10.6 255.255.255.252 N/A R1-ISP Fa0/0 192.168.254.253 255.255.255.0 N/A S0/0/0 10.10.10.5 255.255.255.252 10.10.10.6 R2-Central Fa0/0 172.16.255.254 255.255.0.0 N/A N/A 192.168.254.254 255.255.255.0 192.168.254.253 Eagle Server N/A 172.31.24.254 255.255.255.0 N/A host Pod# A N/A 172.16. Pod#.1 255.255.0.0 172.16.255.254 host Pod# B N/A 172.16. Pod#. 2 255.255.0.0 172.16.255.254 S1-Central N/A 172.16.254.1 255.255.0.0 172.16.255.254 All contents are Copyright © 1992–2007 Cisco Systems, Inc. All rights reserved. This document is Cisco Public Information. Page 1 of 7 CCNA Exploration Network Fundamentals: OSI Network Layer Lab 5.5.1: Examining a Route Learning Objectives Upon completion of this lab, you will be able to: • Use the route command to modify a Windows computer routing table. • Use a Windows Telnet client command telnet to connect to a Cisco router. • Examine router routes using basic Cisco IOS commands. Background For packets to travel across a network, a device must know the route to the destination network. This lab will compare how routes are used in Windows computers and the Cisco router. -
DVR Network Setup Connect the DVR to a Router Using a Networking
DVR Network Setup Connect the DVR to a router using a networking cable. The cable should snap in on both ends. Connect a monitor and mouse to the DVR. Power on the DVR. On a computer connected to the same router as the DVR: Go to the Start Menu and Search or Run "cmd". If using Windows 8 or 10, press Windows + X and select "Command Prompt" Type in "ipconfig" and press enter. Write down the IP address, subnet mask, and default gateway. If using Mac OS X, go to System Preferences->Network->Advanced and note the IPv4 address, subnet mask, and router (gateway) address. You can skip the wizard on the DVR if it comes up. On the DVR , go to Menu->Configuration->Network->General. The default login is user “admin” and password “aaaa1111” (or “12345” on revision 1 units). Uncheck “Enable DHCP” Set the IPv4 address to the same as the PC's except the last 3 digits . The last 3 digits must be unique on the network (not used by any other device including the default gateway). If you don't know which addresses are already in use, check your router's list of connected devices. The last 3 digits should be less than 254 and greater than 1. Some routers may have additional restrictions on the range of allowed addresses. Here we have selected "112" for the last 3 digits. Write down the new IP address. Set the IPv4 Subnet and Default Gateway numbers to be same as the PC's. The Prefered DNS Server can be either your Gateway number (192.168.1.1 in this example) or the DNS address provided by your ISP. -
Chapter5(Ipv4 Address)
Chapter 5 IPv4 Address Kyung Hee University 1 5.1 Introduction Identifier of each device connected to the Internet : IP Address IPv4 Address : 32 bits The address space of IPv4 is 232 or 4,294,967,296 The IPv4 addresses are unique and universal Two devices on the Internet can never have the same address at same time Number in base 2, 16, and 256 Refer to Appendix B Kyung Hee University 2 Binary Notation and Dotted-Decimal Notation Binary notation 01110101 10010101 00011101 11101010 32 bit address, or a 4 octet address or a 4-byte address Decimal point notation Kyung Hee University 3 Notation (cont’d) Hexadecimal Notation 0111 0101 1001 0101 0001 1101 1110 1010 75 95 1D EA 0x75951DEA - 8 hexadecimal digits - Used in network programming Kyung Hee University 4 Example 5.1 Change the following IPv4 addresses from binary notation to dotted-decimal notation a. 10000001 00001011 00001011 11101111 b. 11000001 10000011 00011011 11111111 c. 11100111 11011011 10001011 01101111 d. 11111001 10011011 11111011 00001111 Solution We replace each group of 8 bits with its equivalent decimal number (see Appendix B) and add dots for separation. a. 129.11.11.239 b. 193.131.27.255 c. 231.219.139.111 d. 249.155.251.15 Kyung Hee University 5 Example 5.4 Change the following IPv4 address in hexadecimal notation. a. 10000001 00001011 00001011 11101111 b. 11000001 10000011 00011011 11111111 Solution We replace each group of 4 bits with its hexadecimal equivalent. Note that hexadecimal notation normally has no added spaces or dots; however, 0x is added at the beginning of the subscript 16 at the end a. -
Introduction to IP Multicast Routing
Introduction to IP Multicast Routing by Chuck Semeria and Tom Maufer Abstract The first part of this paper describes the benefits of multicasting, the Multicast Backbone (MBONE), Class D addressing, and the operation of the Internet Group Management Protocol (IGMP). The second section explores a number of different algorithms that may potentially be employed by multicast routing protocols: - Flooding - Spanning Trees - Reverse Path Broadcasting (RPB) - Truncated Reverse Path Broadcasting (TRPB) - Reverse Path Multicasting (RPM) - Core-Based Trees The third part contains the main body of the paper. It describes how the previous algorithms are implemented in multicast routing protocols available today. - Distance Vector Multicast Routing Protocol (DVMRP) - Multicast OSPF (MOSPF) - Protocol-Independent Multicast (PIM) Introduction There are three fundamental types of IPv4 addresses: unicast, broadcast, and multicast. A unicast address is designed to transmit a packet to a single destination. A broadcast address is used to send a datagram to an entire subnetwork. A multicast address is designed to enable the delivery of datagrams to a set of hosts that have been configured as members of a multicast group in various scattered subnetworks. Multicasting is not connection oriented. A multicast datagram is delivered to destination group members with the same “best-effort” reliability as a standard unicast IP datagram. This means that a multicast datagram is not guaranteed to reach all members of the group, or arrive in the same order relative to the transmission of other packets. The only difference between a multicast IP packet and a unicast IP packet is the presence of a “group address” in the Destination Address field of the IP header. -
Hikvision IP Camera Setup
Hikvision IP camera setup Introduction: In this guide we will go through the necessary steps to enable a Hikvision IP camera to be accessible on a network and viewable through a web browser. Step 1: First plug your camera into your network switch or router and make sure it has power either through POE or using a power supply. Next, locate the CD that came with your Hikvision IP camera and insert it into a PC. There should be a folder named SADP. Inside you will see a file labeled SADP Setup, double click this file to begin the installation. Once the installation is done the program should automatically open and list any Hikvision devices connected to your network. (The Default IP address is 192.0.0.64) Step 2: Next you will need to find the Default Gateway for your network. To do this click on the start menu, in the search bar at the bottom type in "cmd" then press enter. This will bring up the command prompt window. In the command prompt window type "ipconfig" then press enter. This will bring up information such as your IP address, Subnet Mask, and Default Gateway. Now, find where it says Default Gateway and you should have a set of numbers listed to the right. Write this down or take note of it because we will use it here soon. (You can see in the example below our Default Gateway is: 192.168.1.1, keep in mind that yours may be different, that is okay.) Step 3: Now that we have the Default Gateway go back to the SADP program and select your IP camera by clicking on it. -
Changing the IP Address Scope of the Media Gateway to Allow Use of Customer-Owned Routers
Changing the IP Address scope of the media gateway to allow use of customer-owned routers This method does not require making any changes to the customer-owned router and can be completed by accessing the Media Gateway’s router and the powercycling of devices. The HomeConnect functionality may not be available on some devices when using this method. HomeConnect functionality may not work correctly using this method and devices connected to the Gateway’s Ethernet ports or wireless may not be able to communicate with devices connected to the customer’s router. Description The wireless can be enabled on both the Ultra TV Media Gateway and the customer- owned router at the same time. The DHCP is enabled on the customer-owned router and the Media Gateway, and both have a separate IP address scope to assign to connected devices. The customer- owned router is connected to the “1” Ethernet port of the Gateway using the Internet/WAN port on the router. Example This image shows how devices are connected to the Media Gateway and the customer-owned router. Configuring the Gateway 1. Access the Media Gateway: a. Enter “192.168.0.1” into the address bar of any web browser. b. Press the “Enter” key. c. Enter “technician” in the User Name field. d. Enter “WOWpass” in the Password field. If the user name and password combination do not work, the customer must call WOW! to have the password reset. e. Click the “Apply” button. 2. Click the “LAN Setup” tab. 3. Enter “192.168.2.1” in the IP Address field.