1. Cisco networking CNET-448
Chapter Introduction
Cisco networking CNET-448
Chapter 7
Wide Area Networks
(WAN)
Prepared by: Sikandar Shah

2. Objectives Chapter Introduction
Topics Covered in this chapter include:
IP Routing Technologies
Configure and verify operation status of a Serial interface.
WAN Technologies
Identify different WAN Technologies
DSL
Frame relay
VPN
Troubleshooting
Troubleshoot and Resolve WAN implementation issues
Serial interfaces
PPP

3. WAN Network Major characteristics of WANs:
WANs generally connect devices that are separated by a broader geographic area than a LAN can serve.
WANs use the services of carriers such as telcos, cable companies, satellite systems, and network providers.
WANs use serial connections of various types to provide access to bandwidth over large geographic areas.

4. WAN Network Topologies
WAN Basic
WAN Network Topologies
Star or hub-and-spoke topology Fully meshed topology

5. WAN Network Topologies
WAN Basic
WAN Network Topologies
Partially meshed topology

6. WAN Network components
WAN Basic
WAN Network components

7. WAN
WAN Terms
Customer premises equipment (CPE): It is typically owned by the subscriber and located on the subscriber’s premises.
CSU/DSU: It is used to connect data terminal equipment (DTE) to a digital circuit, such as a T1/T3 line. The CSU/DSU provides clocking of the line to the router.
Demarcation Point(Demarc): It is the precise spot where the service provider’s responsibility ends and the CPE begins. The CSU/DSU (CPE) is connected to the Demarc.
Local loop: The local loop connects the demarc to the closest switching office.
Central office (CO): This point connects the customer’s network to the provider’s switching network. It is also called POP.
Toll network : The toll network is a trunk line inside a WAN provider’s network. This network is a collection of switches and facilities owned by the Internet service provider (ISP).

8. WAN Connection speeds WAN Name Speed Channels DS0 64Kbps 1 DS0 DS1/T1
1.544Mbps
24 DS0s
DS2
6.312Mbps
96 DS0s
DS3/T3
44.736Mbps
28 DS1s =(28x24) DS0s E1
2.048Mbps
30 DS0s
OC3
155.52Mbps
3(DS3/T3) = 2,016 DS0s
OC-12
622.08Mbps
4-OC3s
OC-48
Mbps
4-OC12s

9. WAN Connection Types WAN
Dedicated (leased lines): These are usually referred to as a point-to-point or dedicated connections. A leased line is a pre-established WAN communications path that goes from the CPE through the DCE switch, then over to the CPE of the remote site.
Circuit switching: No data can transfer before an end-to-end connection is established.
Packet switching: This is a WAN switching method that allows you to share bandwidth with Other companies to save money.

10. WAN
WAN Protocols
Frame Relay: Frame Relay is a high-performance Data Link and Physical layer specification. It provides features for dynamic bandwidth allocation and congestion control.
ISDN: Integrated Services Digital Network (ISDN) is a set of digital services that transmit voice and data over existing phone lines. ISDN offers a cost-effective solution for remote users and is also used as a backup link with Frame Relay or T1.
HDLC: High-Level Data-Link Control (HDLC) was derived from Synchronous Data Link Control (SDLC).
PPP: PPP can be used to create point-to-point links between different vendors’ equipment. It uses a Network Control Protocol (NCP) field in the Data Link header to identify the Network layer protocol being carried, provide authentication, dynamic addressing and multilink connections to be run over asynchronous and synchronous links.

11. WAN Protocols WAN PROTOCOLS
PPPoE: PPP over Ethernet encapsulates PPP frames in the Ethernet frames. It has lower maximum transmission unit(MTU) than Ethernet.
DSL: Digital subscriber line is a technology used by telephone companies to deliver data and video over twisted-pair copper telephone wires.
Symmetrical DSL: The speed for both downstream and upstream connections is equal, or symmetrical. SDSL has a service distance of 12,000 feet at high speeds.
Asymmetrical DSL: Different transmission speeds occur between two ends of a network—downstream speed is always faster.
MPLS: Multiprotocol Label Switching (MPLS) is a data-carrying mechanism that emulates some properties of a circuit-switched network over a packet-switched network. MPLS is a switching mechanism that imposes labels (numbers) to packets and then uses them to forward packets. The labels usually correspond to a path to layer 3 destination addresses.

12. Cisco Intelligent WAN (IWAN)
WAN PROTOCOLS
Cisco Intelligent WAN (IWAN)
The Cisco IWAN enables application service-level agreements (SLAs), endpoint type, and network conditions so that Cisco IWAN traffic is dynamically routed to deliver the best- quality experience.

13. WAN
DTE and DCE
Router interfaces are typically data terminal equipment (DTE), and they connect into data communication equipment (DCE) like a channel Service unit/data Service Unit (CSU/DSU) using a V.35 connector. CSU/DSU then Plugs into a demarcation location (demarc) and is the service provider’s last responsibility.
Corp#sh controllers s0/0/0

14. PPP Session Establishment and PPP stack

15. PPP Authentication Methods
WAN
PPP Authentication Methods
Password Authentication Protocol (PAP): Passwords are sent in clear text and PAP is performed only upon the initial link establishment.
Challenge Handshake Authentication Protocol (CHAP): It is used at the initial start-up of a link and at periodic check-ups on the link to ensure that the router is still communicating with the same host using MD5 hash function.

16. WAN
PPP Client (PPPoE)
PPPoE (Point-to-Point Protocol over Ethernet) encapsulates PPP frames in Ethernet frames and uses common PPP features like authentication, encryption, and compression.
Basically, PPPoE is a tunneling protocol that layers IP and other protocols running over PPP with the attributes of a PPP link.

17. Virtual Private Networks
WAN
Virtual Private Networks
A virtual private network (VPN) allows the creation of private networks across the Internet, enabling privacy and tunneling of non-TCP/IP protocols. A VPN actually makes your local host part of the remote network by using the WAN link that connects you to the remote LAN. The VPN will make your host appear as though it’s actually local on the remote network. A VPN allows us to connect to these resources by locally attaching to the VLAN through a VPN across the WAN.

18. Enterprise-managed VPNs
WAN
Enterprise-managed VPNs

19. Enterprise-managed VPNs categories
Remote Access
Enterprise-managed VPNs categories
Remote access: VPNs allow remote users such as telecommuters to securely access the corporate network wherever and whenever they need to.
Site-to-site VPNs, or intranet VPNs, allow a company to connect its remote sites to the corporate backbone securely over a public medium like the Internet instead of requiring more expensive WAN connections like Frame Relay.
Extranet VPNs allow an organization’s suppliers, partners, and customers to be connected to the corporate network in a limited way for business-to business (B2B) communications.

20. Provider-managed VPNs
WAN
Provider-managed VPNs
Layer 2 MPLS VPN: It use MPLS labels to transport data. The communication occurs between routers known as provider edge routers (PEs).
Layer 3 MPLS VPN: A different IP subnet connects each site. Neighbor adjacency is established between your router, called CE, and the provider router that’s called PE.

21. WAN
Tunneling Protocols
Layer 2 Forwarding (L2F): It is a Cisco-proprietary tunneling protocol. A VPDN allows a device to use a dial-up connection to create a secure connection to a corporate network. L2F was later replaced by L2TP.
Point-to-Point Tunneling Protocol (PPTP): It was created by Microsoft to allow the secure transfer of data from remote networks to the corporate network.
Layer 2 Tunneling Protocol (L2TP): Jointly created by Cisco and Microsoft to replace L2F and PPTP. L2TP merged the capabilities of both L2F and PPTP into one tunneling protocol.
Generic Routing Encapsulation (GRE): It is another Cisco- proprietary tunneling protocol. It forms virtual point-to-point links, allowing for a variety of protocols to be encapsulated in IP tunnels

22. IPSec Security Protocols
WAN Security
IPSec Security Protocols
Authentication Header (AH): The AH protocol provides authentication for the data and the IP header of a packet using a one- way hash for packet authentication. First the sender and then receiver generates a one-way hash. If the packet has changed in any way, it won’t be authenticated and will be dropped. IPsec relies upon AH to guarantee authenticity.
Encapsulating Security Payload (ESP): It provides confidentiality, data origin authentication, connectionless integrity, anti-replay service, and limited traffic-flow confidentiality by defeating traffic flow analysis.

23. WAN
GRE Tunnels
Generic Routing Encapsulation (GRE) is a tunneling protocol that can encapsulate many protocols inside IP tunnels. A GRE tunnel interface supports a header for each of the following:
A passenger protocol or encapsulated protocols like IP or IPv6, which is the protocol being encapsulated by GRE.
GRE encapsulation protocol
A Transport delivery protocol, typically IP

24. WAN Security
EBGP
BGP is a distance-vector protocol, which means that it advertises all or a portion of its route table to its neighbors.
BGP supports classless networks, the use of variable length subnet masks (VLSMs), and summarization.
BGP uses metrics called attributes to influence the selection of the best path to remote networks.
BGP supports a nonhierarchical network structure .
BGP uses the concept of autonomous systems to define the boundaries of networks and treats communications among neighbors differently depending on whether the neighbors belong to the same autonomous system or not.
BGP relies upon TCP for connection-oriented, acknowledged communications using port 179.
BGP neighbors either live in the same AS, referred to as internal BGP (iBGP) neighbors, or live in different ASs, in which case they are referred to as external BGP (eBGP) neighbors.

25. STUDY RESOUCES
Further Study Links
Read through the Exam Essentials section together in class
Open your books and go through all the written labs and the review questions.
Review the answers in class.