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This article compares the different components of network architecture, including addressing/routing, network management, performance, and security. It explores the mechanisms and interactions within each component and their impact on the network.
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UNIT 4 NETWORK ARCHITECTURE
Comparison between Architecture and design Similarity is that both architecture and design attempt to solve multi dimensional problems , where the variables could be performance, security and network management
Component Architecture • 1.Component Architecture is the description of how and where each function of a network is applied within that network. It consists of a set of mechanisms , by which that function is applied to the network, and a set of internal relationships between these mechanisms • Functions of a network represent major capabilities like addressing and routing, network management , performance and security • Mechanisms are h/w or s/w that help a n/w achieve each capabilities • Internal relationships consist of interactions , protocols and messages and are used to optimize each function within the network. • Tradeoff’s are decision points in the development of the network • Dependencies occur when mech. Relies on another for its operation. • Constraints are restrictions that one mech., places on another.
In developing a component architecture consists of determining the mechanisms that make up each component, how the mechanisms work and how that component works as a whole • For Example : to develop the component performance Performance component QoS Service Level Agreement Policies mechanisms
QoS is applied to each network device to control its resources in support of its SLA and policies • SLA ties subscribers to service levels • Policies provide high level of frame work for service levels , SLA’s and QoS • A Service Level Agreement (SLA) is a formal definition of the relationship that exists between a service provider and its customer. A SLA can be defined and used in the context of any industry, and is used to specify what the customer could expect from the provider, the obligations of the customer as well as the provider, performance, availability and security objectives of the service, as well as the procedures to be followed to ensure compliance with the SLA
Addressing/ Routing Component Architecture • 1.Addressing is applying addresses / identifiers to devices at various protocol layers • 2. Routing is learning about the connectivity within and between the networks and applying this connectivity to forward IP packets towards their destinations • This component architecture determines • How user , management traffic flows are prapagated . • Determines the degree and diversity in the network • How areas of the network can be divided MECHANISMS ADDRESSING MECHANISMS ROUTING MECHANISMS
ADDRESSING MECHANISMS PRIVATE ADDRESSING VIRTUAL LANS VARIABLE LENGTH SUBNETTNG IPv6 NAT SUPERNETTING DYNAMIC ADDRESSING SUBNETTING
Routing mechanisms SWITCHING AND ROUTING MULTICASTS DEFAULT ROUTTE PROPAGATION MOBILE IP CIDR ROUTE FILTERING ROUTING POLICIES PEERING IGP AND EGP SELECTION AND LOCATION
Network Management Component and Architecture • It provides functions to control, plan ,allocate ,deploy ,co-ordinate and monitor network resources • NMA is important as it determines how and where management mechanisms are applied in the network • Other architectural components require interactions with NMA • It describes how other network functions are monitored and managed Network Management Mechanisms Managing network management data Monitoring Instrumentation Scaling network management traffic Configuration Centralised and distributed management FCAPS Integration into OSS Inband and outband Management MIB selection Checks and balances
PERFORMANCE COMPONENT ARCHITECTURE • Performance consists of the set of mechanisms used to configure , operate manage provision and account for resources in the network that allocate performance to users, applications and devices • Performances applies at multiple layers • This component describes how resources are allocated to user and management traffic flows • Prioritizing, scheduling and conditioning traffic flows are part of the duties of this component. Co-relation between users, applications and devices to traffic flow, traffic engineering, access control, quality of service policies and SLA are the other mechanisms used in this component
Security component Architecture 1.Security is a requirement to guarantee the confidentiality, integrity, and availability of users, applications , devices and network information and physical resources 2. This component also provides privacy 3. This component describes how system resources are to be protected from theft, damage, DoS, or unauthorized access4. These mechanisms can be targeted towards specific areas of the network , such as external interfaces, aggregation points or at devices …etc 4.This component determines to what level of security and privacy are needed, where the critical areas are and how it will impact and interact with other architectural components Mechanisms Security threat analysis Security policies and procedures Encryption protocol and application security Physical security and awareness Network perimeter security Remote access security
Reference Architecture • It is a description of the complete network architecture and contains all of the component architectures being considered for that network • Compilation of the internal and external architectures • Once the component architectures are determined their relationships with one another are determined • It incorporates the effects that functions have on one another • Based on the requirements , traffic flows and goals , the reference architecture is either b lanced or weighted. • In a balanced architecture all functions , constraints and dependencies are minimized , trade offs between functions are balances so that no individual function is prioritized over the other • When one or more functions are prioritized over the others , the external relationship between these functions and the other functions would be weighted in favor of this function
To develop component architectures requires input from sets of users, applications and device requirements, estimated traffic flow and architectural goals • For ex: user application and device requirements are used as criteria to evaluate mechanisms for the performance and security component architectures • Component architectures , requirements , flows and goals are all interwoven through the reference architecture
External Relationships • External Relationships define the relationships between different functions within a network as well as the requirements from the users , applications and devices. • The addressing and routing component architecture supports traffic flow from each and every other function • OPTIMIZING THE REFERENCE ARCHITECTURE • Interaction between performance and security • Interaction between network management and security • Interaction between network management and performance • Interaction between addressing / routing and performance
Architectural Models • In developing the architectural models there are three types of models • Topological models • Flow based models • Functional models • Topological models • These are based on geographical or topological arrangement • there are two models a) LAN/MAN/WAN model b) Access/Distribution/Core model • LAN/MAN/WAN model • It is based on the geographical or topological distances between the networks • It focuses on the features and requirements of these boundaries • Compartmentalising functions , services , performances and features of the network along those boundaries • They indicate the hierarchy needed in the network • Access/Distribution/Core model • 1.It compartmentalises similar to lan model • 2. It focuses on functions rather than on locations
3. It reflects the behaviour of the network at its access, distribution and core areas 4. Access areas are closest to the users and it is these areas that most of the traffic is sourced and sinked 5. Distribution areas are most likely to be to or from multiple – user devices such as servers or specialised devices 6.The core of the network is used for bulk transport of the traffic, and flows are usually not sources or sinked at the core
Flow Based Models • The flow based architectural models are based on the flow based model used in analysis • The peer to peer architectural model is based on the peer to peer flow model , where the users and their applications are fairly consistent in their behaviours • This pushes the functions, features and services towards the edge of the network • This resembles the core portion of the access/ Distribution/Core model • The client server architectural model also follows its flow model, but in this case there are obvious locations for architectural features—i.e where flows combine • Functions/ features and services are focussed at server locations, interfaces to client LAN and client server flows • Hierarchical client server models these Functions/ features and services are also focussed at server-server flows • In distributed computing architectural model the data sources and sinks are obvious locations for architectural features
Functional Models • Functional Architectural models focus on supporting particular functions in the network • In the service provider architectural model , functions focus on privacy, security , service delivery ,and billing • In the intranet and extranet architectural models security and privacy including the separation of users, devices and applications based on secure access are focused • In the single/ multi tier performance architectural model focuses o identifying networks or parts of a network as having a single tier performance , multiple tiers of performance or having components of both • End to end architectural model focuses on all components
Functional Models SERVICE PROVIDER ARCHITECTURAL MODEL
Systems and Network architecture • Wile developing the network architecture , we may need to develop the systems architecture • Systems Architecture is a superset of a network architecture , where majoe relationships between components are described • It gives a totla picture of the system that includes , servers, storage devices, apps…etc
ADDRESSING FUNDAMENTALS • Network address identifies a system uniquely on a network Address IP Address Mask Address 2. General format of the address is A.B.C.D 3. The IP address consists of two parts (i) the network id (ii) the host id 4. The mask helps us to identify which bits are the network id and which bits are the host id 5. The network id helps us to determine whether an address is on local network or on a remote network address 6. There are different kinds of addresses (i)Local address (ii) global address (iii) private address (iv) public address (v) temporary address (vi) persistent address
7. Local Address are those that are used in local communications , like the Ethernet address which are not advertised outside the local area network 8.Global address are needed when the packets are to be transmitted between networks 9. Public IP addresses are those that can be advertised and forwarded by network devices in the public domain 10 . Private IP addresses are those that cannot be advertised or forwarded by network devices in the public domain 11. Addresses like link layer addresses are called as permanent addresses 12. IP addresses are either temporary or permanent
ROUTING FUNDAMENTALS • Routing entails learning about reachability within and between networks and then applying this reachability information to forward IP packets towards their destinations • Routers learn reachability either statically or dynamically. • For static learning information is configured permanently into the routers. • For dynamic learning routers use routing protocols like RIP, OSPF, and BGP. • Traditionally a router looks at the network portion of the packets destination address to determine where it needs to be sent. The router compares this destination address to the contents of its routing table and chooses the best route for that destination.
ADDRESSING MECHANISMS • The popular mechanisms are • Classful addressing • Subnetting • Variable length Subnetting • Supernetting • CIDR • Private addressing • Network address translation • Dynamic addressing
Classful Addressing • Classful addressing is applying a mask to addresses to support a range of network sizes. • There are five classes of addresses • a) Class A b) Class B c) Class C d) class D e) Class E
Figure 4-2 Occupation of the address space
In classful addressing, the address space is divided into five classes: A, B, C, D, and E.
