Wide Area Networking

Overview

• Defining WAN Terms

• WAN Connection Types

• High-Level Data-Link Control

• Point-to-Point Protocol

• Frame Relay

• ISDN

Defining WAN Terms

• Customer premises equipment (CPE) is equipment that’s owned by the subscriber and located on the subscriber’s premises.

• Demarcation point is the spot where the service provider’s responsibility ends and the CPE begins.

• Local loop connects the demarc to the closest switching office, called a central office.

• Central office (CO) This point connects the customers to the provider’s switching network.

WAN Connection Types

DCE and DTE

High-Level Data-Link Control

• HDLC is a point-to-point protocol used on leased lines.• HDLC is the default encapsulation used by Cisco routers over

synchronous serial links.• Cisco’s HDLC is proprietary everyone’s HDLC implementation is

proprietary.

Point-to-Point Protocol

• Point-to-Point Protocol (PPP) is a Data Link layer protocol that can be used over either asynchronous serial (dial-up) or synchronous serial (ISDN) media.

• It is non-proprietary, which means that if you don’t have all Cisco routers, PPP would be needed on your serial interfaces

• It uses the LCP (Link Control Protocol) to build and maintain data-link connections.

• Network Control Protocol (NCP) is used to allow multiple Network layer protocols (routed protocols) to be used on a point-to-point connection.

• Link-establishment phase LCP packets are sent by each PPP device to configure and test the link.

• Authentication phase If required, either CHAP or PAP can be used to authenticate a link. Authentication takes place before Network layer protocol information is read.

• Network layer protocol phase PPP uses the Network Control Protocol (NCP) to allow multiple Network layer protocols to be encapsulated and sent over a PPP data link.

PPP Session Establishment

Configuring PPP on Cisco Routers

• Turn on PPP on connected interface

Router(config)#int s0

Router(config-if)#encapsulation ppp

• Configuring PPP Authentication

Router(config)#hostname RouterA

RouterA(config)#username RouterB password cisco

RouterA(config)#int s0

RouterA(config-if)#ppp authentication chap pap

Troubleshooting PPP

• What is an error in this configuration?

Troubleshooting PPP

• What is an error in this configuration?

Troubleshooting PPP

• What is an error in this configuration?

Frame Relay

• Frame Relay has become one of the most popular WAN services deployed.

• Frame Relay is a packet-switched technology.• Frame Relay, by default, is classified as a non-broadcast multi-

access (NBMA) network, which means that it does not send any broadcasts, such as RIP updates, across the network by default.

Frame Relay Encapsulation Types

• When configuring Frame Relay on Cisco routers, you need to specify it as an encapsulation on serial interfaces.

• You can’t use HDLC or PPP with Frame Relay.

• With Frame Relay there are two encapsulation types: Cisco and IETF (Internet Engineering Task Force).

RouterA(config)#int s0

RouterA(config-if)#encapsulation frame-relay ietf

• The default encapsulation is Cisco unless you manually type in ietf. But you need ietf encapsulation, if you want to connect Cisco device to a non-Cisco device with Frame Relay.

Data Link Connection Identifiers

• Frame Relay PVCs are identified to DTE end devices using Data Link Connection Identifiers (DLCIs).

• DLCI values used on Frame Relay interfaces to distinguish between different virtual circuits.

• Inverse ARP (IARP) is used with DLCIs in a Frame Relay network. that it maps a DLCI to an IP address

• You can see the IP-to-DLCI mappings with the show frame-relay map command.

Local Management Interface

• Local Management Interface (LMI) is a signaling standard used between your router and the first Frame Relay switch it’s connected to.

• It allows for passing information about the operation and status of the virtual circuit between the provider’s network and the DTE (your router).

• There are three different types of LMI message formats: Cisco, ANSI, and Q.933A. The different kinds depend on the type and configuration of the telco’s switching gear.

• It’s imperative to configure your router for the correct one, which should be provided by the telco.

• On Cisco equipment, the default type is Cisco, but you may need to

change to ANSI or Q.933A, depending on what your service provider tells you.

• ANSI ----- > American National Standards Institute:

• ITU-T ------> International Telecommunication Union-Telecommunication

Frame Relay Implementation

RouterA(config)#int s0/0

RouterA(config-if)#no shut

RouterA(config-if)#encapsulation frame-relay ietf

RouterA(config-if)#ip address 172.16.20.1 255.255.255.0

RouterA(config-if)#frame-relay lmi-type ansi

RouterA(config-if)#frame-relay interface-dlci 101

Monitoring Frame Relay

CommandUse

show frame lmi•Give you the LMI traffic statistics exchanged between the local router and the Frame Relay switch.

show frame pvc• list all configured PVCs and DLCI numbers.•It provides the status of each PVC connection and traffic statistics.

show interface• Check for LMI traffic.• Displays line, protocol, DLCI, and LMI information.

show frame map• Displays the Network layer–to–DLCI mappings.

Troubleshooting Frame Relay

• What is the problem in this configuration?

Troubleshooting Frame Relay

• what type of WAN network do you have? ISDN, DSL, Wireless, or Frame Relay?

Integrated Services Digital Network

• Integrated Services Digital Network (ISDN) is a digital service designed to run over existing telephone networks.

• ISDN can support both data and voice.

• ISDN is actually a set of communication protocols proposed by telephone companies that allow them to carry a group of digital services

• PPP is typically used with ISDN to provide data transfer, link integrity, and authentication.

• These are the benefits of ISDN: It can carry voice, video, and data simultaneously. Call setup is faster than with an analog modem. Data rates are faster than on an analog modem connection. Small office and home office sites can be economically

supported with ISDN BRI services

ISDN Connections

• Integrated Services Digital Network (ISDN) Basic Rate Interface (BRI) is two B (Bearer) channels of 64k each.

• ISDN BRI routers come with either a U interface or something known as an S/T interface.

• The difference between the two is that the U interface is already a two-wire ISDN convention that can plug right into the ISDN local loop.

• the S/T interface is a four-wire interface• that basically needs an adapter (network termination type 1 (NT1)) to

convert from a four-wire to the two-wire ISDN specification.

ISDN Terminals

• TE1 A terminal equipment type 1 (TE1) device refers to those terminals that understand ISDN standards and can plug right into an ISDN network.

• TE2 A terminal equipment type 2 (TE2) device refers to those that before ISDN standards

• NT1 The network termination 1 (NT1) device implements the ISDN Physical layer specifications and connects the user devices to the ISDN network by converting the network from a four-wire to the two-wire network used by ISDN.

• TA A terminal adapter (TA) converts TE2 non-ISDN signaling to signaling that’s used by the ISDN switch. It connects into an NT1 device for conversion into a two-wire ISDN network.

ISDN Components

ISDN Bandwidth• Basic Rate Interface (BRI)

ISDN Basic Rate Interface (BRI) service, also known as 2B+D, provides two B channels and one D channel.

The BRI B-channel service operates at 64Kbps and carries data, while the BRI D-channel service operates at 16Kbps and usually carries control and signaling information.

When configuring ISDN BRI, you’ll need to obtain service profile identifiers (SPIDs), and you should have one SPID for each B channel. The SPID is a unique number.

• Primary Rate Interface (PRI) In North America and Japan, the ISDN Primary Rate Interface

(PRI) service also known as 23B+D delivers 23 64Kbps B channels and one 64Kbps D channel, for a total bit rate of 1.544Mbps.

ISDN Configuration

• When configuring ISDN, you’ll need to know the type of switch that your service provider is using.

• To see which switches your router will support, use the isdn switch-type ? command in global configuration mode

• That is the list of switch type supported by Cisco router.

ISDN Configuration

• For each ISDN BRI interface, you need to specify the SPIDs that are configured for the circuit by the service provider using the isdn spid1 and isdn spid2 interface subcommands.

• These are provided by the ISDN provider and identify you on the switch, sort of like a telephone number.

RouterA(config)#isdn switch-type basic-ni

RouterA(config)#int bri0

RouterA(config-if)#encap ppp (optional)

RouterA(config-if)#isdn spid1 086506610100 8650661

RouterA(config-if)#isdn spid2 086506620100 8650662