Per Virtual Circuit Compression Payload Compression

The Frame Relay Forum (FRF) Technical Committee approved an implementation agreement for data compression over Frame Relay called FRF.9. This agreement specifies a standard for compression to ensure multivendor interoperability see Frame Relay Standards in Chapter 14. FRF.9 is a per-virtual circuit compression mechanism for both switched virtual circuits (SVCs) and permanent virtual circuits (PVCs), which is negotiated at the time that the DLCI is started. Cisco currently supports FRF.9 mode 1...

References and Additional Reading

ADSL, VDSL, andMulticarrier Modulation. John Wiley and Sons Inc., 2000. Birkner, Matthew H. Cisco Internetwork Design. Cisco Press, 2000. Black, Ulysses D. Frame Relay Networks Specifications and Implementations. McGraw Hill, ---. ISDN and SS7 Architecture for Digital Signaling Networks. Prentice Hall, 1997. Boyles, Tim and David Hucaby. CCNP Switching Exam Certification Guide. Cisco Press, 2000. Buckwalter, Jeff T. Frame Relay Technology and Practice. Addison-Wesley Longman...

LAPF Control Protocol

For frame switching services, the LAPF control protocol is used along side the LAPF core protocol. This protocol is the full Q.922, and it is implemented both in the user's system and in the network (called the frame handler). Figure 14-4 shows one of the common formats, where the information field carries a higher-layer PDU and represents Frame Relay with other end-to-end protocols above LAPF, thus providing error and flow control. Here again, the Flag and Address fields and FCS are the same...

Text Dial Out Configuration

For a text dial-out service, you must first make a decision on whether to use local authentication on the router or to use an authentication server. These users do not call into the modems, so security is probably not as much of a concern as a dial-in pool. In the case of dial-out, the user connects through text on a VTY port, which means that the type of authentication is login. A small fictitious insurance company is used as the example. The company has eight WAN sites, all on dedicated...

Virtual Profiles

A virtual profile is another instance of virtuality, which is intended to overcome the limitations of network scalabilty. It is based on the same functionality-specific technique, where the user-specific configuration information can be applied to any remote user. The configuration information for virtual profiles can come from either a virtual interface template, or per-user configuration information that is stored on an access control server (ACS), or both, depending on how the router and ACS...

NAT and PAT

NAT and PAT are design solutions that create private address space, in the sense that these addresses only exist inside the private network and not in the public address space. These techniques allow designers of future network implementations to achieve some important goals, including the following Provide a firewall technique Reduce time and cost by simplifying IP address management In its simplest configuration, NAT operates on a router that connects two networks together. One of these...

Acknowledgments

This book wouldn't be possible if I didn't have the continuous and unconditional support of my managers Felicia Brych, who devoted her time for months to make this book happen, and Chuck Trent and Henry White, who encouraged me and created an unmatchable atmosphere of trust and encouragement to ensure the success of this project. Special appreciation goes to my Sprint E-Solutions manager, Debra Wieland, and to Chris Starsiak for believing in me and for the support. Many thanks to Brett Bartow...

Setting the ISDN Switch Type

The switch types supported in the latest versions of IOS (12.1.x. and later) are outlined in Example 10-1. The most commonly used types in the U.S. and Canada are basic-5ess, basic-dms100, and basic-ni1. Example 10-1 Determining the ISDN Switch Type Example 10-1 Determining the ISDN Switch Type Northern Telecom DMS-100 switch type for the US NET3 switch type for the UK, Europe, Asia and Australia National ISDN switch type for the US TS013 switch type for Australia (obsolete) Besides the listed...

PPP Dial Out Configuration

The following PPP dial-out configuration section refers to the second type of PPP dial-out mentioned earlier in this chapter, where the router dials into a service provider to gain access to the LAN behind the router. First, a fixed password is required for this type of configuration, and you must gather a few pieces of information about your service provider. Dialup the provider with a PC and gather the DNS server addresses, the WINS server addresses (if any), and the domain name assigned to...

About the Author

Plamen Nedeltchev was born in February 1954 in Silistra, Bulgaria. He graduated from high school as valedictorian in 1972. In 1980, he received an M.S. (Summa Cum Laude) from Saint Petersburg State Electro-Technical University. In 1989, he received his Ph.D. from the Bulgarian Academy of Science, Sofia, Bulgaria. Plamen worked as the chief information officer of VMT (a division of the Ministry of Transport of Bulgaria) in his country of origin. He joined Sprint E-Solutions in 1999 as a senior...

AS5x00 Specific Commands and Debugs

High-density Cisco dial routers include the AS5100, AS5200, AS5300, AS5400, and AS5800 series routers. These devices were all developed for an ISP to provide dial-in services for a wide variety of customers. All these devices are modular so that if a modem or a group of modems is faulty, a feature card can be replaced instead of the entire router. The AS5100 series router is no longer in production, but was solely a router with a lot of external modems on line cards connected to it, all in one...

Isdnshow negotiationFor 77x routers

Troubleshooting PPP Callback for ISDN As described in Chapter 11, this PPP feature provides a method for an implementation to request a dial-up peer to call back. When callback is successfully negotiated at the LCP phase and the authentication phase of PPP is complete, instead of going to the NCP phase, PPP disconnects the link. A sample of checking the functionality of the callback feature is shown in Example 12-32. Example 12-32 ISDN Callback Output From the debug isdn 931 Command ISDN BR0 TX...

Large Scale DialIn Configuration

A large-scale dial-in configuration does not significantly differ from a regular dial-in configuration. In most cases, it just requires that you use an access server, which provides extended capacity versus any router with a few async ports. To configure an access server such as an AS5300 or AS5400, use the same PPP or text and PPP dial-in configuration as covered in the previous section. The group range of the group-async interface must increase to include all modems in the router. The IP pool...

Layer 1 BRI

ISDN standards require the availability of three types of services for end-to-end connections by the local exchange carrier (LEC) Circuit-switched services on B channels Circuit-switched or packet-switched services on D channels Packet-switched services on B channels 238 Chapter 9 ISDN Technology Background To use them, the ITU-T defined BRI and PRI access interfaces, and the operation speed and the number and type of channels. The BRI is also referred to as 2B+D, and typically operates over...

Disconnect

328 Chapter 12 ISDN BRI Troubleshooting The router informs the switch that it wants to make a call. The switch transforms the Q.931 messages to SS7 and places a call to the remote switch. The remote switch translates the call to Q.931 signals and calls the remote router. Q.931 is not an end-to-end protocol, but in terms of troubleshooting, it's more convenient to consider Q.931 as an end-to-end protocol, especially when the ISDN network belongs to a single provider. Layer 2 INFO frames transmit...

PPP DialIn Configuration

All PPP dial-in configurations must have a set of the same elements, whether only one or one hundred modems are attached. The first key element is authentication. This can be done locally with a fixed username and password configured on the router or with an authentication, authorization, and accounting (AAA) server. AAA servers can run TACACS+ or RADIUS services for authentication. To apply any aaa configuration, you must first issue the command aaa new-model. This instructs the router to user...

Frame Relay and Upper Layer Protocols

Flow control and error recovery functions can be performed by the full LAPF protocol. Typically, the full LAPF is not used in PVC circuits. Therefore, these functions must be performed by the higher-layer protocols, which are encapsulated in the PDU as a component of the information field of the frame format. This approach is the most commonly implemented today. To ensure the interoperability of Frame Relay and higher-layer protocols, two major issues must be addressed multiprotocol support and...

LCP Problems and the Magic 22 Seconds

One of the most complicated issues is when everything works correctly and the router makes calls out, but after the router disconnects, the call results in one of the following If the disconnect is immediately after call out (less than one second), there's either a wrong phone number or it is not provisioned for data. The error messages in Chapter 12 provide more explanations about the possible cause. If the call disconnects in two seconds, the other party is not configured to be called from...

Frequently Asked Questions and Answers

The questions and answers in this section apply to the majority of users. These solutions will generally fix the problems you or your clients are experiencing. If you still have a problem after taking into account everything listed here, search Cisco's web site for more recent troubleshooting information and, if required, open a TAC case for further investigation. Question How can I achieve faster connection speeds Answer To start, some situations simply cannot be helped or improved. First,...

Step One Verify that the Modem Is Ready to Accept Calls

The first event to occur is that the modem must pick up the call. If it is an external modem, increase the volume so that you can hear it. Place a call from a telephone to the modem to make sure it answers. If it does not, check the cabling between the modem and the router. The type of cable can differ between modems, so the easiest way to check is through the show line line-number command. The line you must check is the following If the modem is ready to take an incoming call, but there is no...

Step 4 Select a Solution and Test It

At this step, you must test your solution. The objective is to prove that you are able to make the extra traffic uninteresting and prevent the router from dialing out. The recommended debug settings are Dial on demand events debugging is on The expected result from the debugging the process is displayed in Example 13-19. Aug 1 06 30 25.886 ISDN-6-LAYER2UP Layer 2 for Interface BR0, TEI 88 changed to up *Aug 1 06 30 25.910 ISDN-6-LAYER2UP Layer 2 for Interface BR0, TEI 97 changed to up The...

Line and Clocking Problems

Clocking problems in serial connections can lead to either chronic loss of the connection or to degraded performance. The most common indicators for physical layer problems are shown in Example 17-3. 494 Chapter 17 Frame Relay Troubleshooting Example 17-3 If This Service Is Provisioned for 56-kbps, Check the Status of Serial 0 Serial0 unassigned YES NVRAM down down < output omitted> Under 1602-frame show interface serial 0, the last line reports the status of the physical layer DCD down DSR...

Controller and Line Status

Start with the physical condition and integrity of the T1 line. Always check the status of the T1 controllers and verify that you do not receive any errors. The command that displays the status is show controllers t1, as shown in Example 7-1. Example 7-1 Output of the Command show controllers t1 The circuit is up according to the next line Cable length is shown next. If the circuit is not long, it needs to be configured differently Cablelength is long gain36 0db Description T1 with Pacific...

LCP Phase of PPP

The following explanations are based on the output you see if you type the debug ppp negotiation command to troubleshoot LCP issues. The first part of the output identifies how PPP treats the connection. For every dial case, it is treated as a dedicated line. The first step in LCP takes place when the dial server sends an outgoing configuration request (O CONFREQ), as shown in Example 7-9. Example 7-9 Debug Output of PPP Outgoing Configuration Request MagicNumber 0XE82CFF9C (0X0506E82CFF9C) The...

Troubleshooting PPP Network Control Protocols

NCPs are a set of protocols that negotiate the upper-layer protocols. Every negotiation is a series of requests and acknowledgments Vil IPCP I CONFREQ and Vi1 IPCP I CONFACK REQsent . During the negotiation process, you can see IPCP, IPXCP (these are not included in Example 12-29), CDPCP, and CCP negotiating IP, IPX, CDP, and COMPRESSION, respectively. The negotiation depends on the configuration and the process starts by establishing the virtual connection, which is a bundle of channels called...

Frame Relay Standards

A specific feature of Frame Relay technology is the ability to use packet sizes that are greater than 1500 bytes, which are common in LAN environments. Some estimates show that the packet size can be up to 16 kilobytes, remembering that the embedded frame check sequence (FCS) can handle up to 4-kilobyte packets. (See Part IV for more information.) Frame Relay combines the statistical multiplexing and port sharing of X.25 with the highspeed and low-delay characteristics of time-division...

Troubleshooting Ppp Lcp

PPP LCP provides a method of establishing, configuring, maintaining, and terminating the point-to-point connections. LCP goes through four distinct phases Link establishment and configuration negotiation 336 Chapter 12 ISDN BRI Troubleshooting Network-layer protocol configuration negotiation First, link establishment and configuration negotiation occurs before any network layer datagrams (IP, AT, and IPX) are exchanged. LCP first opens the connection and negotiates configuration parameters. At...

Serial Interface 0 and Line Protocol Is Down

When the interface serial 0 is not administratively down, the clocking problems have to be your primary focus, especially when the router reports the output in Example 17-12. Example 17-12 The Line Problems Are Evident from This Output Serial0 is Down, Line Protocol is Down Hardware is QUICC Serial (with onboard CSU DSU) < output omitted> In general, this problem occurs because clocking is not available. The following cases describe situations when the serial interface is not...

Frame Relay Fragmentation

The upper-layer protocols use different formats and usually the information field contains more than one T1.618 frame. T1.617A Annex F and RFC 1490 address the fragmentation process. When a packet must be fragmented, the fragmentation protocol adds an encapsulation header to it and divides the packet into many smaller fragments, according to network requirements. Each fragment receives a fragmentation header (see Figure 15-7). In the example, the size of the IP packet is greater than the size...

Troubleshooting the Physical Layer

The physical layer involves various components, but your main focus is the local loop wiring and clocking. If you have a physical loop, there is clocking, which refers to both timing and synchronization. It is important to understand what's required by the local exchange carrier (LEC) to provide a local loop to the user. Two wires from the line card in the ISDN switch go to a bundle of pairs in the central office (CO) and might split many times into different media, conduits, directions, and...

ISDN Switch Types

There are many standards for switches because most standards were released during or after the deployment of most ISDN switches. Therefore, a variety of ISDN switch manufacturers pose different requirements for configuring CPE. In Table 9-7, the Cisco supported switches from the latest IOS release are listed. Lucent 5ESS switch type for the U.S. Northern Telecom DMS-100 switch type for the U.S. NET3 switch type for UK, Europe, Asia, and Australia National ISDN switch type for the U.S. TS013...

Ping and Privileged Extended Ping Commands

These commands are available for Cisco, Microsoft, and UNIX platforms. The ping utility can determine basic connectivity. It is based on the specifications for RFC 1256 and RFC 791. Ping is assigned a low priority. It is not an indicator of performance, and it is not used for other more sophisticated tests. During a ping test, the host sends an ICMP echo packet and receives a reply ICMP message if basic connectivity exists. NOTE An ICMPv6 is available for the IPv6 protocol (see RFC 1885). The...

Preconfiguring the Routers on Both Ends

The first thing you must consider is the router that's immediately available to you. It's a good idea to use any Cisco ISDN router, such as Cisco 776, Cisco 804, Cisco 1604, and so on, to perform initial testing of the remote user's router. If you are a network administrator who is responsible for a relatively big ISDN environment, it's a good idea to have an ISDN line at your desk. For example, the Cisco 77x router at your desk with a simple configuration can help you perform initial...

Information Data Field of the LAPF Control Protocol Frame

In the LAPF control protocol, the information field carries both non-data (signaling) and user data information. A Frame Relay network uses four categories of signaling messages In general, the information field uses two formats as shown in Figure 14-10. In the figure, IE indicates the information elements. Figure 14-10 Information Field Formats The IE fields carry higher-layer protocol information such as user data and higher-layer overhead and routing updates. It is transparent to the Frame...

EIGRP and HSRPBased Solutions

A more sophisticated backup mechanism is available in Cisco IOS using the EIGRP routing protocol and a combination of floating and static routing. Both one- and two-router based configurations are available. For a full description of the solutions, see the Cisco Press book Advanced IP Network Design (CCIE Professional Development) by Alvaro Retana, Don Slice, and Russ White. An important element of the configuration is to prevent an IP route-cache 474 Chapter 16 Basic and Advanced Frame Relay...

Line Code Errors

On both a PRI and a T1, time slots exist for each of the 64-kbps channels. (See Chapter 2, Telecommunication Basics, for more information.) As the data is received, a time slot generator places the bits into these time slots. There can never be more than seven 0s in a row, even across time slots, and this is where line coding must be considered. If eight 0s are in a row, the time slot generator converts the eight 0s to a combination of 0s and 1s, depending on the line code. (See Figure 2-10 for...

Seven Layer OSI Model

In the 1980s, the European-dominated International Standards Organization (ISO) began to develop its OSI networking suite. OSI has two major components an abstract model of networking (the basic reference model, or seven-layer model), and a set of concrete protocols. This model eventually grew into the Internet, to which the core Internet protocols adhere. This section discusses the layers of the OSI model. The physical layer is concerned with transmitting raw bits over a communication channel....

Performance Issues Related to the Physical Layer

You can experience line problems even if the router reports that the line is not down, as shown in the output in Example 17-14. Example 17-14 The Line Shows Up and the Protocol Is Up, But the Performance Issues Exist Serial1 is up, line protocol is up < output omitted> However, the connection experiences slow performance, intermittent connectivity, and high latency. Some of the most common reasons for poor performance follow Cables longer than 50 feet 15.24 meters or cables are unshielded...

Troubleshooting Dial Out Service

When an outbound call is placed, the output in Example 7-21 is generated from dial-on-demand events and PPP protocol negotiation debugging. The commands that enable this debugging include debug dialer and debug ppp negotiation. Example 7-21 Debug Output of Dialer and PPP Negotiation for an Outgoing Call Example 7-21 Debug Output of Dialer and PPP Negotiation for an Outgoing Call As65 DDR Dialing cause ip (s 192.168.0.2, d 216.115.102.82) As65 DDR Attempting to dial 6222230 no matching chat...