Scaling Networks – Dropbox Paper

A Quick Study Guide for CCNA Course - Scaling Networks

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  12/04/2018Scaling Networks – Dropbox Paper  Scaling Networks   Hierarchical Network Design  Three layers in hierarchical network design - Access Layer - The access layer provides connectivity for the users. User traffic is initiated at this layer. It provides - Layer 2 switching, high availability, port security, Address Resolution Protocol inspection, Virtual Access Control Lists, Spanning Tree, Power over Ethernet (PoE) and auxiliary VLANs for VoIP, etc.   Distribution Layer - The distribution layer is used to forward traffic from one local network to another. It provides -  Aggregation of LAN or WAN links, Redundancy and Load Balancing, Route  Aggregation and Summarization, Routing services between LANs, WANs and routing domains (EIGRP to OSPF, etc.), etc.   Core Layer - The core layer represents a high-speed backbone layer between dispersed networks. It provides - high speed switching, reliability, fault tolerance, etc.   Cisco Enterprise Architecture    12/04/2018Scaling Networks – Dropbox Paper  It consists of - Enterprise Campus - The Enterprise Campus consists of the entire campus infrastructure, to include the access, distribution, and core layers. In addition, it can also includes other submodules such as - Server Farm and Data Center Module   (This area provides high-speed connectivity and protection for servers)  , Services Module   (This area provides access to all services, such as IP Telephony services, wireless controller services, and unified services.)  Enterprise Edge - The Enterprise Edge consists of the Internet, VPN, and WAN modules connecting the enterprise with the service provider's network. This module extends the enterprise services to remote sites and enables the enterprise to use Internet and partner resources. Service Provider Edge - The Service Provider Edge provides Internet, Public Switched Telephone Network (PSTN), and WAN services. All data that enters or exits the Enterprise Composite Network Model (ECNM) passes through an edge device.  Remote - Failure Domains  A well-designed network not only controls traffic, but also limits the size of failure domains. The use of redundant links and reliable enterprise-class equipment minimize the chance of disruption in a network. A failure domain  is the area of a network that is impacted when a critical device or network service experiences problems. In the hierarchical design model, it is easiest and usually least expensive to control the size of a failure domain in the distribution layer  .  Switch Block Deployment - Routers, or multilayer switches, are usually deployed in pairs, with access layer switches evenly divided between them. This configuration is referred to as a building, or  12/04/2018Scaling Networks – Dropbox Paper departmental, switch block . Each switch block acts independently of the others. Failure of a single device does not impact the whole network.  Expanding the network   Design for Scalability   Use expandable, modular equipment or clustered devices.   Include design modules that can be added, upgraded and modified, without affecting the design of the other functional areas of the network.   Create a hierarchical addressing scheme.  Create an IPv4 or IPv6 address strategy that is hierarchical. Careful IPv4 address planning eliminates the need to re-address the network to support additional users and services.  Use routers or multilayer switches to limit broadcasts and filter traffic. Choose routers or multilayer switches to limit broadcasts and filter other undesirable traffic from the network. Use Layer 3 devices to filter and reduce traffic to the network core.  Planning for Redundancy  One method of implementing redundancy is by installing duplicate equipment  and providing failover services for critical devices. Another method of implementing redundancy is redundant paths . Redundant paths offer alternate physical paths for data to traverse the network. Redundant paths in a switched network support high availability.  Increasing Bandwidth   Link aggregation  allows an administrator to increase the amount of bandwidth between devices by creating one logical link made up of several physical links. EtherChannel is a form of link aggregation used in switched networks. EtherChannel uses the existing switch ports; therefore, additional costs to upgrade the link to a faster and more expensive connection are not necessary.  Expanding the Access Layer  An increasingly important aspect of extending access layer connectivity is through wireless connectivity.  Fine-tuning Routing Protocols  Link-state routing protocols such as Open Shortest Path First  (OSPF), works well for larger hierarchical networks where fast convergence is important. Another popular routing protocol for larger networks is Enhanced Interior Gateway Routing Protocol  (EIGRP). Cisco developed EIGRP as a proprietary distance vector routing protocol with enhanced capabilities.  Five Categories of Switches (for Enterprise Networks)   Campus LAN Switches - To scale network performance in an enterprise LAN, there are core, distribution, access, and compact switches. These switch platforms vary from fanless switches with eight fixed ports to 13-blade switches supporting hundreds of ports. Campus LAN switch platforms include the Cisco 2960, 3560, 3750, 3850, 4500, 6500, and 6800 Series.  12/04/2018Scaling Networks – Dropbox Paper   Cloud-Manages Switches - The Cisco Meraki cloud-managed access switches enable virtual stacking of switches. They monitor and configure thousands of switch ports over the web, without the intervention of onsite IT staff.  Data Center Switches - A data center should be built based on switches that promote infrastructure scalability, operational continuity, and transport flexibility. The data center switch platforms include the Cisco Nexus Series switches and the Cisco Catalyst 6500 Series switches.  Service Provider Switches - Service provider switches fall under two categories: aggregation switches and Ethernet access switches. Aggregation switches  are carrier-grade Ethernet switches that aggregate traffic at the edge of a network. Service provider Ethernet  access switches feature application intelligence, unified services, virtualization, integrated security, and simplified management.  Virtual Networking - Networks are becoming increasingly virtualized. Cisco Nexus virtual networking switch platforms provide secure multi-tenant services by adding virtualization intelligence technology to the data center network.  Switch Hardware   Forms of Switch   Fixed - built-in, permanent interfaces and ports.  Modular - expansion of capacity and speed using upgradable line/port cards.  Stackable - ability to interconnect multiple switches to effectively manage them as one large switch.  Non-stackable - cannot to interconnected to multiple switches .  Port Density - The port density of a switch refers to the number of ports available on a single switch. Forwarding Rates - Forwarding rates define the processing capabilities of a switch by rating how much data the switch can process per second. Power over Ethernet (PoE) - PoE allows the switch to deliver power to a device over the existing Ethernet cabling. This feature can be used by IP phones and some wireless access points. Multilayer Switching - Multilayer switches are typically deployed in the core and distribution layers of an organization's switched network. Multilayer switches are characterized by their ability to build a routing table, support a few routing protocols, and forward IP packets at a rate close to that of Layer 2 forwarding. Router Hardware  Routers use the network portion of the destination IP address to route packets to the proper destination. They select an alternate path if a link goes down or traffic is congested. All hosts on a local network specify the IP address of the local router interface in their IP configuration. This router interface is the default gateway .  Role and functions of router  interconnecting multiple sites within an enterprise network providing redundant paths connecting ISPs on the Internet
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