Frame Relay Oversubscription

Frame Relay is a nonbroadcast WAN that uses oversubscription to realize cost savings over dedicated private-line networks. Oversubscription occurs when the sum of the services supported by an interface is greater than the interfaces configured bandwidth. Oversubscribing a Frame Relay service is not necessarily bad. For example, in a hub-and-spoke network topology, oversubscription prevents the likelihood of several remote sites sending or receiving from the head-end site at the same time...

Show framerelay map

The show frame-relay map command is used (in EXEC mode) to display the current map entries and information about the connections. The following example demonstrates the show frame-relay map command and its displayed output, and Table 169 describes the output Serial 1 (administratively down) ip 131.108.177.177 TCP IP Header Compression (inherited), passive (inherited) Table 16-9. show frame-relay map Field Descriptions A Frame Relay interface and its status (up or down). In this example, the...

Voice over Frame Relay VoFr

Voice over Frame Relay (VoFr) has been recently enjoying the general acceptance of any efficient and cost-effective technology. In the traditional plain old telephone service (POTS) network, a conventional (with no compression) voice call is encoded, as defined by the ITU pulse code modulation (PCM) standard, and utilizes 64 kbps of bandwidth. Several compression methods have been developed and deployed that reduce the bandwidth required by a voice call down to as little as 4 kbps, thereby...

Figure 23 Broadcast Network

Multimedia broadcast traffic is a much more bandwidth-intensive broadcast traffic type. Multimedia broadcasts, unlike data broadcasts, typically are several megabits in size therefore, they can quickly consume network and bandwidth resources. Broadcast-based protocols are not preferred because every network device on the network must expend CPU cycles to process each data frame and packet to determine if that device is the intended recipient. Data broadcasts are necessary in a LAN environment,...

Note

The ARP table can be viewed from any host by entering the command arp at a DOS prompt C > arp then it displays and modifies the IP-to-Physical address translation tables used by ARP Displays current ARP entries by interrogating the current protocol data. If inet_addr is specified, the IP and Physical addresses for only the specified computer are displayed. If more than one network interface uses ARP, entries for each ARP table are displayed. Displays the ARP entries for the network interface...

Show ip vrf

The show ip vrf command is used to display the set of defined VRFs (VPN routing forwarding instances) and associated interfaces. See Table 23-8 for a show ip vrf description. show ip vrf brief detail interfaces vrf-name output-modifiers show ip vrf brief detail interfaces vrf-name output-modifiers Table 23-8. show ip vrf Syntax and Description (Optional) This displays concise information on the VRF(s) and associated interfaces. (Optional) This displays detailed information on the VRF(s) and...

IEEE 8023 Logical Relationship to the OSI Reference Model

Figure 3-3 illustrates the IEEE 802.3 logical layers and their relationship to the OSI reference model. As with all IEEE 802 protocols, the data link layer is divided into two IEEE 802 sublayers the Media Access Control (MAC) sublayer and the MAC-client sublayer (logical-link control or bridge). The IEEE 802.3 physical layer corresponds to the OSI model physical layer (Layer 1). Figure 3-3. Ethernet and the IEEE 802.3 OSI Reference Model Figure 3-3. Ethernet and the IEEE 802.3 OSI Reference...

DSL Transceiver Unit xTUR

The remote transceiver unit is the customer site equipment for the service user's connection to the DSL loop. The xTU-R connection is typically 10Base-T, V.35, ATM-25, or T1 E1. XTU-Rs are available in a number of different configurations depending on the specific service being provisioned. In addition to providing basic DSL modem functionality, many XTU-Rs contain additional functionality, such as bridging, routing, TDM, or ATM multiplexing. Protocol transparent endpoints behave very much like...

Tunneling Protocols Supported

PPTP with Windows Dial-Up Networking 1.3 Tunneling protocols do not function without an underlying infrastructure protocol, typically PPP. PPP is one of the most common access protocols in use today and is the default for most desktop operating systems (Windows 2000 NT, 9x). PPP is actually a suite of standardized protocols, much like TCP IP, that work together to provide a multitude of services used to establish and maintain point-to-point connections. PPP provides many features, including...

Time Division Multiplexing TDM Hierarchy

North America and Canada identify the digital time division multiplexing (TDM) hierarchy as T, as in T1, T3, and so on. Japan identifies the digital TDM hierarchy as J, as in J1, J3, and so on. International identification of the digital TDM hierarchy is E, as in E1, E3, and so on. Table 13-1 details the number of DS0 channels and data rates for each TDM hierarchy level. Table 13-1. North American, Canadian, Japanese, and International TDM Carrier Standardsm Table 13-1. North American,...

Figure 261 Provider Based Unicast Address Format RFC 1884

The following list describes Figure 26-1, defining the unicast address format in detail. Format prefix Indicates the type of address as provider-based unicast. This is always 3 bits, and it is coded as 010. Registry ID Identifies the Internet address registry from which this ISP obtains addresses. This is a 5-bit value indicating the Internet Assigned Numbers Authority (IANA) or one of the three regional registries, namely the Internet Network Information Center (InterNIC), R seaux IP Europ ens...

DSL Modulation Techniques

BRI-ISDN provides up to two 64 kbps bearer, or B-channels, plus a 16 kbps D-channel used for signaling and packet data. The information payload plus other overhead associated with implementation results in 160 kbps in total transmitted information. A key requirement of ISDN was to reach the customers over existing non-loaded copper wire loops, equating to 18,000 feet. However, an Alternate Mark Inversion (AMI) implementation of Basic Rate ISDN would require use of the lower 160,000 Hertz. This...

Soft Errors

Soft errors allow the ring-recovery protocols to restore normal token operation, but they cause performance degradation due to a disruption in the network operation. Soft errors include the following Circulation of priority tokens or frames Multiple monitors on the ring Wiring issues (loose or faulty) Type 1 These require no ring recovery function to be executed. Type 2 These require the ring-purge process to be executed. Type 3 These require the monitor contention and ring-purge processes to...