Cisco Router 800 Series Software Configuration Guide
Have a look at the manual Cisco Router 800 Series Software Configuration Guide online for free. It’s possible to download the document as PDF or print. UserManuals.tech offer 53 Cisco manuals and user’s guides for free. Share the user manual or guide on Facebook, Twitter or Google+.
xxxix Cisco 800 Series Software Configuration Guide 78-5372-06 About This Guide Obtaining Additional Publications and Information http://www.cisco.com/en/US/about/ac123/ac147/about_cisco_the_internet_ protocol_journal.html Training—Cisco offers world-class networking training, with current offerings in network training listed at this URL: http://www.cisco.com/en/US/learning/le31/learning_recommended_training _list.html
About This Guide Obtaining Additional Publications and Information xl Cisco 800 Series Software Configuration Guide 78-5372-06
CHAPTER 1-1 Cisco 800 Series Software Configuration Guide 78-5372-06 1 Concepts This chapter contains conceptual information that may be useful to Internet service providers (ISPs) or network administrators when configuring Cisco 800 series and Cisco SOHO series routers. To review some typical network scenarios, see “Network Scenarios” in Chapter 2. For information on specific configurations, see Chapter 7, “Router Feature Configuration,” and Chapter 8, “Advanced Router Configuration.” This chapter includes the following topics: Overview of Cisco 800 Series and Cisco SOHO Series Routers, page 1-2 ADSL, page 1-4 DNS-Based X.25 Routing, page 1-5 Network Protocols, page 1-6 Routing Protocol Options, page 1-8 PPP Authentication Protocols, page 1-9 TACACS+, page 1-11 Network Interfaces, page 1-11 Dial Backup, page 1-14 NAT, page 1-15 Easy IP (Phase 1), page 1-16 Easy IP (Phase 2), page 1-17 Cisco Easy VPN Client, page 1-17 VoIP, page 1-18
Chapter 1 Concepts Overview of Cisco 800 Series and Cisco SOHO Series Routers 1-2 Cisco 800 Series Software Configuration Guide 78-5372-06 QoS, page 1-20 Access Lists, page 1-25 Overview of Cisco 800 Series and Cisco SOHO Series Routers The Cisco 801, 802, 803, and 804 routers are Cisco IOS-based members of the Cisco 800 router product line supporting Integrated Services Digital Network (ISDN) connections. The Cisco 805 router includes one 10BASE-T Ethernet port and one serial port, which can connect EIA/TIA-232, EIA/TIA-449, EIA/TIA-530, EIA/TIA-530A, X.21, and V.35 data terminal equipment (DTE) or data communications equipment (DCE). The Cisco 806 and Cisco SOHO 71 routers are fixed-configuration IP routers with security features that provide a secure Ethernet gateway for users in small offices, branch offices and home offices using broadband access to the Internet. These routers are designed to work with digital subscriber line (DSL), cable, or long-reach Ethernet (LRE) modems, or with an Ethernet switch serving a multitenant unit. These routers have four 10BASE-T Ethernet ports that function as a hub; the routers also have one 10BASE-T Ethernet WAN port. The Cisco 811 and 813 routers connect small professional offices or telecommuters over ISDN Basic Rate Interface (BRI) lines to corporate LANs and the Internet. These routers offer multiprotocol routing between LAN and WAN ports. The Cisco 813 router includes the same features as the 811, but adds two telephone ports, and it has four Ethernet ports instead of just one. The Cisco 826 and 827 and Cisco SOHO 76 and 77 routers are Cisco IOS-based members of the Cisco 800 router family with ATM and Asymmertric Digital Subscriber Line (ADSL) support. Depending on their feature set, the routers send data, voice, and video over high-speed ADSL lines to connect to the Internet or corporate intranets. The data-only Cisco 826, 827, and 827H routers and the Cisco SOHO 76 and 77 routers have one 10BASE-T Ethernet and one ADSL-over-ISDN or ADSL network port, respectively.
1-3 Cisco 800 Series Software Configuration Guide 78-5372-06 Chapter 1 Concepts Overview of Cisco 800 Series and Cisco SOHO Series Routers The data-and-voice Cisco 827-4V router has four Foreign Exchange Station (FXS)/plain old telephone service (POTS) ports in addition to the 10BASE-T Ethernet port and one ADSL network port, and it supports Voice over IP (VoIP). The four FXS/POTS ports will support loop-start functions for connecting to POTS devices up to 500 ft. The Cisco 827-4V router includes a digital signal processor (DSP) chip to support VoIP over ATM adaptation layer (AAL5) protocol. AAL5 operates over the ADSL physical interface for both data and voice. The ADSL protocol supports EOC message sets defined in T1.413 DMT Issue 2 as limited by digital subscriber line access multiplexers (DSLAMs). The ADSL controller and line interface unit are based on Alcatel chip sets. The Cisco 828 router is Cisco IOS-based with ATM/SHDSL support. The Cisco SOHO 78 router also supports ATM/SHDSL. The routers send data, voice, and video over high-speed G.SHDSL lines to connect to the Internet or corporate intranets. Both the Cisco 828 router and the Cisco SOHO 78 router provide a 4-port Ethernet hub, in addition to the G.SHDSL port. Both the Cisco 831 router and the Cisco SOHO 91 Ethernet-to-Ethernet routers can connect a corporate telecommuter or small office to an ISP over a broadband or Ethernet connection to corporate LANs or the Internet. The routers are capable of bridging and multiprotocol routing between LAN and WAN ports. The Cisco 831 router is a hardware encryption–capable router offering business-class features to small offices and enterprise telecommuters. The Cisco SOHO 91 router offers software encryption capability without hardware encryption. The Cisco 836 and Cisco SOHO 96 routers are ADSL routers with an integrated switch. These routers provide a 4-port Ethernet switch for the LAN and an ADSL physical interface for the WAN compatibility. The Cisco 836 router is a hardware encryption–capable, Ethernet -to-ADSL router offering business-class features to small offices and enterprise telecommuters. The Cisco SOHO 96 router offers software encryption capability without hardware encryption. Both these routers provide an ISDN basic rate interface (BRI) S/T interface as a backup for the ADSL interface. The Cisco 837 and Cisco SOHO 97 routers are ADSL routers with an integrated switch. These routers provide a 4-port Ethernet switch for LAN and an ADSL physical interface for WAN compatibility. The Cisco 837 router is a hardware encryption–capable, Ethernet -to-ADSL router offering business-class features to small offices and enterprise telecommuters. The Cisco SOHO 97 router offers software encryption capability without hardware encryption.
Chapter 1 Concepts ADSL 1-4 Cisco 800 Series Software Configuration Guide 78-5372-06 The Cisco 831, 836, and 837, and Cisco SOHO 91, 96, and 97 routers support switch functions which enable the routers to be connected as a 10/100 BASE-T device. These routers crossover functionality enable them to detect MDI/MDIX to any other PC or hub with a straight-through cable or crossover cable. Ta b l e 1 - 1 summarizes what interface each Cisco model supports. ADSL ADSL is a technology that allows both data and voice to transmit over the same line. It is a packet-based network technology that allows high-speed transmission over twisted-pair copper wire on the local loop (“last mile”) between a network service provider (NSP) central office and the customer site, or on local loops created either within a building or campus. The benefit of ADSL over a serial or dial-up line is that it is always on and always connected, increasing bandwidth and lowering the costs compared with a dial-up or leased line. ADSL technology is asymmetric in that it allows more bandwidth from an NSP’s central office to the customer site than from the customer site to the central office. This asymmetry, combined with always-on access (which eliminates call setup), makes ADSL ideal for Internet and intranet accessing, video-on-demand, and remote LAN access. Table 1-1 Interface Supported in Each Cisco Router Interface Supported Cisco Router Model Ethernet to ISDN 801, 802, 803, 804 Ethernet to serial (both sync and async) 805 Ethernet to Ethernet 806, 831, SOHO 71, SOHO 91 Ethernet to ADSL over ISDN 826, SOHO 76, 836, SOHO 96 Ethernet to ADSL over POTS 827, 827H, 827-4V, 837, SOHO 77, SOHO 77H, SOHO 97
1-5 Cisco 800 Series Software Configuration Guide 78-5372-06 Chapter 1 Concepts SHDSL SHDSL SHDSL is a technology based on the G.SHDSL (G.991.2) standard that allows both data and voice to be transmitted over the same line. SHDSL is a packet-based network technology that allows high-speed transmission over twisted-pair copper wire between a network service provider (NSP) central office and a customer site, or on local loops created within either a building or a campus. G.SHDSL devices can extend reach from central offices and remote terminals to approximately 26,000 feet, at symmetrical data rates from 72 kbps up to 2.3 Mbps. In addition, it is repeatable at lower speeds, which means there is virtually no limit to its reach. SHDSL technology is symmetric in that it allows equal bandwidth between an NSP’s central office and a customer site. This symmetry, combined with always-on access (which eliminates call setup), makes SHDSL ideal for LAN access. DNS-Based X.25 Routing X.25 has long operated over an IP network, specifically using Transmission Control Protocol (TCP) as a reliable transport mechanism. This method is known as X.25 over TCP (XOT). However, large networks and financial legacy environments experienced problems with the amount of route configuration that needed to be done manually because each router switching calls over TCP needed to have every destination configured. Every destination from the host router needed a static IP route statement, and for larger environments, there could be as many as several thousand per router. Until now, the only way to map X.121 addresses and IP addresses was on a one-to-one basis using the x25 route x121address xot ipaddress command. The solution to this problem is to centralize route configuration in a single location that routers can then access for their connectivity needs. This centralization is the function of the Domain Name System (DNS)–based X.25 routing feature, because the DNS server can search and provide all domains and addresses on a network.
Chapter 1 Concepts Network Protocols 1-6 Cisco 800 Series Software Configuration Guide 78-5372-06 With the DNS-based x.25 routing feature, it is easy to manage the X.121-to-IP addressing correlation and the mnemonic-to-X.121 addressing correlation. Instead of the router needing a route statement going to all destinations, all that is needed is a wildcard route statement that covers all addresses in the DNS. Network Protocols Network protocols enable the network to pass data from its source to a specific destination over LAN or WAN links. Routing address tables are included in the network protocols to provide the best path for moving the data through the network. IP The best known Transmission Control Protocol/Internet Protocol (TCP/IP) at the internetwork layer is IP, which provides the basic packet delivery service for all TCP/IP networks. In addition to the physical node addresses, the IP protocol implements a system of logical host addresses called IP addresses. The IP addresses are used by the internetwork and higher layers to identify devices and to perform internetwork routing. The Address Resolution Protocol (ARP) enables IP to identify the physical address that matches a given IP address. IP is used by all protocols in the layers above and below it to deliver data, which means that all TCP/IP data flows through IP when it is sent and received regardless of its final destination. IP is a connectionless protocol, which means that IP does not exchange control information (called a handshake) to establish an end-to-end connection before transmitting data. In contrast, a connection-oriented protocol exchanges control information with the remote computer to verify that it is ready to receive data before sending it. When the handshaking is successful, the computers have established a connection. IP relies on protocols in other layers to establish the connection if connection-oriented services are required. IP exchanges routing information using Routing Information Protocol (RIP), a dynamic distance-vector routing protocol. RIP is described in more detail in the following subsections.
1-7 Cisco 800 Series Software Configuration Guide 78-5372-06 Chapter 1 Concepts Network Protocols G.DMT G.DMT full-rate ADSL is a technology that can expand the usable bandwidth of existing copper telephone lines, delivering high-speed data communications at rates of up to 10 Mbps. The technology brings full-motion video, efficient telecommuting, and high-speed data transmission to the home or business, all without interrupting normal telephone service. American National Standards Institute (ANSI) has published an industry standard (known as T1.413) for full-rate ADSL in the United States. The International Telecommunication Union (ITU) has approved a nearly identical global industry standard for full-rate ADSL, known as G.992.1. The ANSI and ITU specifications call for operations rates of up to 8 Mbps downstream and up to 640 Kbps upstream when operating over telephone lines at a distance of up to 18,000 feet. Standard-compliant full-rate ADSL uses a modulation technique known as discrete multitone, or DMT. DMT divides the upstream and downstream bands into a collection of smaller frequency ranges of approximately 4 kHz subchannel that carries a portion of the total data rate. By dividing the transmission bandwidth into a collection of subchannels, DMT is able to adapt to the distinct characteristics of each telephone line and maximize the data transmission rate. Telephone lines are best suited for transmission of the low frequencies associated with voice traffic (0–4 kHz). The high frequencies that are used for full-rate ADSL transmissions experience distortion and attenuation when sent over telephone lines- the higher the frequency, the more the attenuation. DMT effectively divides the data into a collection of smaller bandwidth transmissions, each of which occupies a smaller frequency range and is optimized to maximize the data throughput in that range. The ANSI and ITU standards have both established DMT as the standard modulation technique for full-rate ADSL. U-R2 U-R2 is a German Deutsche Telekom specification for ADSL over copper loops running ISDN in the base band (lower frequencies). It transmits and receives ADSL signals according to the ITU-T G.992.1 Annex B standard. It is a superset of the G.992.1 Annex B standard, allowing for greater cross-vendor interoperability.
Chapter 1 Concepts Routing Protocol Options 1-8 Cisco 800 Series Software Configuration Guide 78-5372-06 Routing Protocol Options Routing protocols include the following: Routing Information Protocol (RIP) Enhanced Interior Gateway Routing Protocol (EIGRP) RIP and Enhanced IGRP protocols differ in several ways, as shown in Ta b l e 1 - 2. RIP RIP is an associated protocol for IP, and is widely used for routing Internet protocol traffic. RIP is a distance-vector routing protocol, which means that it uses distance (hop count) as its metric for route selection. Hop count is the number of routers that a packet must traverse to reach its destination. For example, if a particular route has a hop count of 2, then a packet must traverse two routers to reach its destination. By default, RIP routing updates are broadcast every 30 seconds. You can reconfigure the interval at which the routing updates are broadcast. You can also configure triggered extensions to RIP so that routing updates are sent only when the routing database is updated. For more information on triggered extensions to Table 1-2 RIP and EIGRP Comparison Protocol Ideal Topology Metric Routing Updates RIP Suited for topologies with 15 or fewer hops.Hop count. Maximum hop count is 15. Best route is one with lowest hop count.By default, every 30 seconds. You can reconfigure this value and also use triggered extensions to RIP. EIGRP Suited for large topologies with 16 or more hops to reach a destination.Distance information. Based on a successor, which is a neighboring router that has a least-cost path to a destination that is guaranteed to not be part of a routing loop.Hello packets sent every 5 seconds plus incremental updates sent when the state of a destination changes.