Category: Network

Quality of Service

November 4, 2016 by Neel Rao

Filed under Network

Last modified November 5, 2016

Quality of Service   Traditionally, network congestion or the timely delivery of traffic has been handled by increasing link bandwidths and switching hardware. This does little to address how one type of traffic can be preferred or delivered ahead of another. Quality of service (QoS) is the overall method used in a network to protect and prioritize timecritical or important traffic. QoS is composed of …

IP Telephony

November 4, 2016 by Neel Rao

Filed under Network

Last modified November 5, 2016

IP Telephony Switched campus networks can carry packets that are related to telephone calls, as well as regular data. Voice over IP (VoIP), otherwise known as IP Telephony (IPT), uses IP Phones that are connected to switched Ethernet ports. To properly and effectively carry the traffic for a successful phone call, a combination of many switching features must be used. For example, the Catalyst switches …

Redundancy and Load Balancing

November 4, 2016 by Neel Rao

Filed under Network

Last modified November 5, 2016

Redundancy and Load Balancing Router Redundancy in Multilayer Switching Multilayer switches can act as IP gateways for connected hosts by providing gateway addresses at VLAN SVIs and Layer 3 physical interfaces. These switches can also participate in routing protocols, just as traditional routers do. For high availability, multilayer switches should offer a means to prevent one switch (gateway) failure from isolating an entire VLAN. This …

Multicast

November 4, 2016 by Neel Rao

Filed under Network

Last modified November 5, 2016

Multicast traffic is typically sent by one source and received by a group of recipients, spread throughout a network and changing over time. Examples of multicast traffic include video streams for instruction or entertainment, certain audio conference calls, and one-to-many PC file imaging applications. Because not everyone on a network wants to receive the traffic from a multicast source, switches and routers must have some …

RAPED SPANNING TREE PROTOCOL – RSTP

October 29, 2016 by Neel Rao

Filed under Network

Last modified November 5, 2016

Rapid Spanning Tree Protocol (RSTP) The IEEE 802.1D Spanning Tree Protocol was designed to keep a switched or bridged network loop free, with adjustments made to the network topology dynamically. A topology change typically takes 30 seconds, where a port moves from the Blocking state to the Forwarding state after two intervals of the Forward Delay timer. As technology has improved, 30 seconds has become …

Protecting the Spanning Tree Protocol Topology

October 29, 2016 by Neel Rao

Filed under Network

Last modified November 5, 2016

Protecting Against Unexpected BPDUs   A network running STP uses BPDUs to communicate between switches (bridges). Switches become aware of each other and of the topology that interconnects them. After a Root Bridge is elected, BPDUs are generated by the Root and are relayed down through the spanning-tree topology. Eventually, all switches in the STP domain receive the Root’s BPDUs such that the network converges …

VLAN TRUNKING PROTOCOL – VTP

October 29, 2016 by Neel Rao

Filed under Network

Last modified November 5, 2016

VLAN Trunking Protocol As the previous chapter demonstrated, VLAN configuration and trunking on a switch or a small group of switches is fairly intuitive. Campus network environments, however, usually consist of many interconnected switches. Configuring and managing a large number of switches, VLANs, and VLAN trunks can quickly get out of control. Cisco has developed a method to manage VLANs across the campus network. The …

Ethernet Concepts

October 22, 2016 by Neel Rao

Filed under Network

Last modified October 22, 2016

Ethernet Concepts This section reviews the varieties of Ethernet and their application in a campus network. Recall how the bandwidth requirements for each network segment are determined by the types of applications in use, the traffic flows within the network, and the size of the user community served. Ethernet scales to support increasing bandwidths and should be chosen to match the need at each point …

Cisco Modular Network Design

October 22, 2016 by Neel Rao

Filed under Network

Last modified October 22, 2016

Cisco Modular Network Design You can design a campus network in a logical manner, using a modular approach. In this approach, each layer of the hierarchical network model can be broken down into basic functional units. These units, or modules, can then be sized appropriately and connected together, while allowing for future scalability and expansion. You can divide enterprise campus networks into the following basic …

Cisco Layer 2 Switch Operation

October 22, 2016 by Neel Rao

Filed under Network

Last modified November 26, 2016

Cisco  Layer 2 Switch Operation Recall that with shared Ethernet networks using hubs, many hosts are connected to a single broadcast and collision domain. In other words, shared Ethernet media operates at OSI Layer 1. Each host must share the available bandwidth with every other connected host. When more than one host tries to talk at one time, a collision occurs, and everyone must back …