Week Six Agenda

1. Week Six Agenda • Attendance • Announcements • Review Week Five • Current Week Information • Upcoming Assignments

2. Review Week Five

3. Routing in the Enterprise Architecture

4. Routing in the Enterprise Architecture Notice that RIP is not a part of an enterprise design • It is considered to be too slow to converge • It is not recommended for large networks • However, it may be adequate for small networks and may exist in legacy networks.

5. EIGRP The Enhanced Interior Gateway Routing Protocol (EIGRP) represents an evolution from its predecessor IGRP. Key capabilities that distinguish EIGRP from other routing protocols include fast convergence, support for variable-length subnet mask, support for partial updates, and support for multiple network layer protocols.

6. EIGRP A router running EIGRP stores all its neighbors' routing tables so that it can quickly adapt to alternate routes. If no appropriate route exists, EIGRP queries its neighbors to discover an alternate route. These queries propagate until an alternate route is found.

7. OSPF OSPF protocol was developed due to a need in the Internet community to introduce a high functionality non-proprietary Internal Gateway Protocol (IGP) for the TCP/IP protocol family. The OSPF protocol is based on link-state technology, which is a departure from the Bellman-Ford vector based algorithms used in traditional Internet routing protocols such as RIP. OSPF has introduced new concepts such as authentication of routing updates, Variable Length Subnet Masks (VLSM), route summarization, and so forth.

8. BGP The Border Gateway Protocol (BGP) is the routing protocol used to exchange routing information across the Internet. It makes it possible for ISPs to connect to each other and for end-users to connect to more than one ISP. BGP is the only protocol that is designed to deal with a network of the Internet's size, and the only protocol that can deal well with having multiple connections to unrelated routing domains.

10. IP sec Internet Protocol security (IPsec) is a framework of open standards for protecting communications over Internet Protocol (IP) networks through the use of cryptographic security services. IPsec supports network-level peer authentication, data origin authentication, data integrity, data confidentiality (encryption), and replay protection.

11. Routers One of the primary jobs of a router is to determine the best path to a given destination. A router learns paths, or routes, from the static configuration entered by an administrator and/or dynamically from other routers, through routing protocols

12. Static Routing Static routes in the routing table Includes: network address and subnet mask and IP address of next hop router or exit interface. Denoted with the code S in the routing table denotes static route. Routing tables must contain directly connected networks used to connect remote networks before static or dynamic routing can be used.

13. Static Routing

14. Dynamic Routing Dynamic Routing Protocols (DRP)are used to add remote networks to a routing table. DRP are used to discover networks DRP are used to update and maintain routing tables DRP automatically discover the network Network discovery is the ability of a routing protocol to share information about the networks that it knows about with other routers that are also using the same routing protocol.

15. Dynamic Routing Maintaining routing tables Dynamic routing protocols are used to share routing information with other router and to maintain and update their own routing table. Dynamic routing protocols not only make a best path determination to various networks, they will also determine a new best path if the initial path becomes unusable (or if the topology changes)

16. Routing Table Routers keep a routing table in RAM A routing table is a list of the best known available routes. Routers use this table to make decisions about how to forward a packet. On a Cisco router the show ip route command is used to view the TCP/IP routing table.

17. Routing Loops A network problem in which packets continue to be routed in an endless circle. Network routining loops are caused by a router(s) or link(s) failure, and the notification of the downed link has not yet reached all the other routers. Over time, normal network growth or merging of networks can result in routing loops. Routing protocols utilize various techniques to lessen the chance of a routing loop.

18. Introduction to WANs A wide area network (WAN) is a computer network that covers a broad area. Typically, it is any network whose communications links cross metropolitan, regional, or national boundaries. WAN transmission facilities are generally provided by service providers (SP), such as telephone companies that charge a usage fee called, a tariff.

19. WAN Connection Types Connecting LANs together over a data communications equipment (DCE) network Dedicated WANs utilize synchronous serial connections. Circuit-switched WANs use telephone company networks with asynchronous serial, and ISDN. Packet-switched WANs use a service provider with synchronous serial.

20. WAN Connection Types Leased lines are typically point-to-point connections or a dedicated connection. The WAN connection path from the CPE, through the DCE switch, to the CPE of the remote site, allowing DTE to communicate at any time with no setup procedures before transmitting data. It uses synchronous serial lines up to 45 Mbps. Excellent for constant transmission data flow. Circuit-switching sets up a line like a phone call. No data can transfer before the end-to-end connection is established. Circuit switching uses dial-up modems and ISDN. It is used for low-bandwidth data transfers.

21. WAN Connection Types Packet switching is a WAN switching method that allows you to share bandwidth with other companies to save money. Packet switching is excellent for bur sty data transfers, packet switching can save you money. Frame relay and X.25 are packet-switching technologies . Speeds can range from 56Kbps to 2.048Mbps.

22. WAN Connection Types Time Division Multiplexing (TDM) is a technique for assigning bandwidth on a single wire, based on pre-assigned time slots, to data from several channels. Bandwidth is allocated to each channel regardless of a station’s ability to send data.

23. WAN Connection Types

24. WAN Protocols Point-to-Point Protocol (PPP) is an industry standard protocol. PPP can be used to create point-to-point links between different vendors’ equipment. It allows authentication and multilink connections and can be run over asynchronous and synchronous links. Asynchronous Transfer Mode (ATM) was created for time sensitive traffic, providing simultaneous transmission of voice, video, and data. ATM uses cells rather than packets that are a fixed 53-bytes long.

25. WAN Protocols An ATM cell consists of a 5-byte header and a 48-byte payload. The payload size of 48 bytes was chosen as described above. ATM defines two different cell formats: NNI (Network-Network Interface) and UNI (User-Network Interface). Most ATM links use UNI cell format.

26. WAN Protocols High-Level Data Link Control (HDLC) HDLC is a Data Link protocol. Designates a method for data encapsulation on synchronous serial links Default encapsulation for Cisco routers Bit oriented layer protocol created by ISO. The HDLC header carries no identification of the type of protocol being carried inside the HDLC encapsulation. Because of this, each vendor that uses HDLC has their own way of identifying the Network layer protocol, which means that each vendor’s HDLC is proprietary for their equipment.

27. WAN Protocols HDLC frames can be transmitted over synchronous or asynchronous links. Those links have no mechanism to mark the beginning or end of a frame, so the beginning and end of each frame has to be identified. This is done by using a frame delimiter, or flag, which is a unique sequence of bits that is guaranteed not to be seen inside a frame. This sequence is '01111110', or, in hexadecimal notation, 0x7E. Each frame begins and ends with a frame delimiter. A frame delimiter at the end of a frame may also mark the start of the next frame. A sequence of 7 or more consecutive 1-bits within a frame will cause the frame to be aborted.

28. WAN Protocols Link Access Procedure, Balanced (LAPB) Connection-oriented protocol at the Data Link layer Possesses much overhead because of strict timeout and windowing techniques LAPB is used instead of the lower-overhead HDLC if your link is very error prone

29. WAN Protocols Integrated Services Digital Network (ISDN) is a service offered by telephone companies, It is a communication protocol that allows telephone networks to carry data, voice, and other digital traffic. ISDN network is a digital communication system that is capable of producing the maximum transmission speed of 1.4Mbps. 128Kbps speed is however more common in the digital technology. It's a international standard for sending data, voice, video over regular digital telephone lines. ISDN uses UTP (unshielded twisted pair cable) for transmission.

30. WAN Protocols Frame Relay is a packet switching protocol for connecting devices on a Wide Area Network (WAN). Frame Relay is a protocol standard for LAN internetworking which provides a fast and efficient method of transmitting information from a user device to LAN bridges and routers.

31. WAN Protocols Frame Relay networks in the U.S. support data transfer rates at T-1 (1.544Mbps ) and T-3 (45 Mbps) speeds. In fact, you can think of Frame Relay as a way of utilizing existing T-1 and T-3 lines owned by a service provider. Most telephone companies now provide Frame Relay service for customers who want connections at 56 Kbps to T-1 speeds. (In Europe, Frame Relay speeds vary from 64 Kbps to 2 Mbps.

32. WAN Protocols Multiprotocol Label Switching (MPLS) replaces the hop-by-hop, individually routed packet model with a connection-oriented model that establishes ‘paths’ to destinations.  Instead of routing each packet based upon its destination address, each packet is labeled such that it can be switched along a pre-defined path.  Thus, a single destination may have multiple paths leading to it, with one path used for voice, one for video, and one for data. MPLS integrates Layer 2 information about network links (bandwidth, latency, utilization) into Layer 3 (IP) within a particular autonomous system or ISP in order to simplify and improve IP packet exchange.

33. WAN Protocols Multiprotocol Label Switching (MPLS) MPLS is a highly scalable, protocol agnostic, data-carrying mechanism. In an MPLS network, data packets are assigned labels. Packet-forwarding decisions are made solely on the contents of this label, without the need to examine the packet itself. This allows one to create end-to-end circuits across any type of transport medium, using any protocol. The primary benefit is to eliminate dependence on a particular Data Link Technology, such as ATM,frame relay, SONET or Ethernet, and eliminate the need for multiple Layer 2 networks to satisfy different types of traffic.

34. WAN Protocols Multiprotocol Label Switching (MPLS) MPLS operates at an OSI Model layer that is generally considered to lie between traditional definitions of Layer 2 (Data Link Layer ) and Layer 3 (NetworkLayer ), and thus is often referred to as a "Layer 2.5" protocol. It was designed to provide a unified data-carrying service for both circuit-based clients and packet-switching clients which provide a datagram service model. It can be used to carry many different kinds of traffic, including IP packets, as well as native ATM, SONET, and Ethernet frames.

35. Transmission Modes Digital transmission, is binary codes of 0 and 1.for transmission. It is necessary to notify the receiving end of precise information such as where the data starts and how long the interval of data is. “Synchronous”and“asynchronous”are the two modes for communicating this information, and it is necessary to confirm which mode a each end supports. With Synchronous Transmission Mode, 64 kbps is the highest available transmission speed, while 57.6 kbps is the highest for Asynchronous Transmission Mode. Drawings

36. Transmission Modes Synchronous signals, signals that play the role of signs are added to the top of the data to be transmitted. With these signals, computers can precisely determine the first position of the characters. This mode can transmit data accurately, making it appropriate for corporate information networks. Synchronous Transmission Mode 0111111001101100110001 Synchronous Signal Data First Char Data Second Char 01111110 01101100 11000101

37. Transmission Modes Asynchronous signals, instead, use a portion of the data that has arrived as a clue, the first position of the character is identified. Two bits are added to each character, a start bit for the beginning and an end bit for the end, making the transmission speed slower. Asynchronous Transmission Mode 001101100101100010110 Start Stop StartStop 00110110010110001011 Data First Char Data Second Char

38. Packet-Switched Network Topologies Star topology is a LAN physical topology with endpoints on the network converging at a common central switch (known as a hub) using point-to-point links. A logical ring topology can be configurated as a physical star topology using a unidirectional closed-loop star rather than point-to-point links. That is, connections within the hub are arranged in an internal ring. Full mesh topology is where every node has either a physical or a virtual circuit linking it to every other network node. A full mesh supplies a great deal of redundancy but is typically reserved for network backbones because of its expense.

39. Packet-Switched Network Topologies Partially meshed topology is where some network nodes form a full mesh, but others are attached to only one or two nodes in the network. Observe the WAN Transport Technology table on pages 298 and 299 in your text book.

40. WAN Transport Technologies DS0 Rate is known as the base channel bandwidth of 64Kbps. A bandwidth of 64Kbps is the bandwidth required for an uncompressed digitized phone conversation. Standard speech less then 4KHz; analog speech is filtered at 4KHz before being sampled. Nyquist Theorem sample at a rate at least two times the input frequency to obtain a signal that represents the true signal. Each sample is encoded into 8 bit octets. This DS0 rate is 8KHz. Per second times 8 bits per sample, which is 64Kbps.

41. Technologies Metro Ethernet technology is based on Ethernet technology to offer the best cost-effective, high speed connectivity for MAN and WAN. DSL technology is a high-bandwidth technology over the traditional copper lines. It is designed to work with two modems at either end of the wire. DSL is a transmission technology that is used by SPs to deliver a wide range of services to subscribers. Asymmetric DSL (ADSL) used over short distances (less then 21meters). Most common type used. Frequency range 100KHz to 1.1Hz. ADSL allows PSTN telephone service concurrently on the same line.

42. Technologies Symmetric (SDSL) DSL allows traffic to be transmitted in both directions at the same speed over a single twisted pair. The distance served with SDSL is 10K feet or 3048.8 meters. SDSL is often referred to as single-pair DSL. SDSL is excellent for running applications like email and web servers. Ling Reach Ethernet (LRE) is a WAN access technology which allows for greater distance than the traditional Ethernet provides. Cable technology is another high-speed copper platform that supports both analog and digital video services over a coaxial cable.

43. Technologies Cabling technology makes use channels for upstream and downstream data flow. One application channel in the coaxial cable is used to upstream signals from the modem to the Cable Modem Termination System (CMTS). The output from the CMTS is handed to either the WAN or the PSTN. A different channel is used for the downstream signals from these Internet Service Providers to the CMTS to the modem. The CMTS converts signals from the modem to IP packets prior to handing them to the IP router for transmission across the Internet. Downstream signals are modulated for transmission across the cable to the modem.

45. Technologies Internet download bandwidth over a cable TV line is shared 27 Mbps. Internet upstream bandwidth over the same shared cable is 2.5 Mbps. Wireless technology electromagnetic waves carry RF signals. It is the option of some, that these waves could be harmful to humans. Synchronous Optical Network/Digital Hierarchy (SONET/SDH) is the ANSI standard for synchronous transmission on fiber optic media. It specifies a base signal rate (OC-1) of 51.84 Mbps and a set of multiples of that rate, known as Optical Carrier levels, up to 9.5 Gbps for OC-192.

46. Technologies SONET/SDH is a circuit based technology that provided uses high speed circuits using TDM framing. Dark fiber is a fiber optic cable(s) leased from an SP. Fiber is typically connected to a company’s own infrastructure. Dark fiber got its name after the dot-com burst. Many of the companies that had the rights to these fiber networks either went bankrupt, or, had to abandon their goals of utilizing this fiber. This resulted in hundreds of thousands of miles of “unlit” (dark) fiber. Dark fiber is optical fiber that is lying in the ground unutilized

47. WAN Bandwidth Optimization Compression is used to reduce the data size to conserve transmission time.

48. Private Addressing What has happened to IPv4 addresses? In 1981, IPv4 Protocol was published. In 1985, about 1/16 of the total IPv4 address space was in use. By mid-2001, about 2/3 of the total IPv4 address space was in use. Since 2001, Internet service providers have been trying to conserve IP addresses. They have assigned only a subset of addresses to customers. Currently, the number of public IP addresses available is insufficient for assigning addresses for an entire network. The answer to this problem is to assign private addresses within a network and to translate these private addresses to public addresses when Internet connectivity is required.

49. Public and Private Concerns Are there public, private, or both types of addressing required? How many end systems will need access to the public network? This includes email, file transfer, or web browsing. How many end systems require access to visible public network(s). This includes e-commerce, such as web servers, database servers, application servers, and public servers. These end systems require globally unambiguous IP addresses. Where will the boundaries be between private and public IP addresses and how will they be implemented?

50. Private Addresses • RFC 1918 sets aside three blocks of private IP addresses: • One (1) Class A address • Sixteen (16) Class B addresses • Two hundred and fifty six (256) Class C addresses • These addresses are for private, internal network use only • Packets containing these addresses are not routed over the Internet • A router should never route RFC 1918 addresses. Typically, ISPs configure the border routers to prevent privately addressed traffic from being forwarded