Enterprise Network Management Chapter 2 By: Yilma Tefera May 2006

Network Element 1.High loading can occur when: 1.Many voice calls are in transit through a PABX 2.Large numbers of ATM virtual circuits are transporting many ATM cells. 3.Large numbers of IP packets are in transit a router. 4.Network topology changes result in routing protocol convergence.

Introducing MPLS: First chunck 1.On a more general note, a good understanding of MPLS is important for appreciating issues such as traffic engineering, network-Qos, and connection oriented IP networks.

The Trend towards IP 1.MPLS allows traffic engineering. 2.MPLS integrates IP Qos with layer 2 Qos 3.Many vendors are providing MPLS capability in their devices-for example, Cisco,Juniper, Nortel Networks,and Marconi.

MPLS concepts 1.MPLS is forwarding technology. Its purpose is to receive an incoming traffic type(layer 2 or 3 )at the network edge, it encapsulate it, and then transmit it through an MPLS core or cloud.

MPLS Concept 1. The LSP is created manually or via a signaling protocol 2.The path taken by the LSP may be either user- specified or computed by LER1. 3.The LSP may have reserved resources, such as bandwidth, along the path.

SNMPv3 Message 1.The BEGIN keyword indicates the start of the MIB 2.The IMPORTS keyword introduce descriptors from external MIBs in a similar way to #include in C and import in Java. The IMPORTS statement identifies the descriptor and the module in which it is defined. 3.The DESCRIPTION keyword provides details about the MIB contente 4.The REVISION Keyword provides details about the MIB

SNMPv3 Message Exchanges SNMPv3 get request SNMPv3 get-NextRequest SNMPv3 getBulkrequest SNMPv3 setRequest SNMPv3 Notifications Access Rights Message Size SNMPv3 Security

SNMPv3 Structure 1.SNMPv3 entity consists of two main components: 2.An SNMP engine 3.A collection of SNMP applications

The SNMPv3 engine 1.It made up of four subcomponents: 1.Dispatcher handles message sending and receiving 2.Message subsystem handles message processing for SNMPv3, SNMPv2c, SNMPv1, and any other models. 3.Security subsystem handles security processing for SNMPv3 user-based security model(USM), SNMPv1/v2c community-based security model, and any additional (newly defined) models. 4.Access control subsystem handles the granting/ rejecting of access to specific managed objects.

The two important of engine subcomponents are. 1.Can hand off the message processing to each other as required. 2.Are themselves extensible entities.

There are five SNMPv3 application 1.Command generators, create SNMP messages. 2.Command reponders, respond to SNMP messages. 3.Notification originators, send trap or inform messages. 4.Notification receivers, receive and process trap or inform messages. 5.Proxy forwarders, forward messages between SNMP entity components.

The message format divided into four section. 1.Common data: These fields occur in all SNMPv3 messages. 2.Security model data: This area has three subsections one general, one for authentication, and one for privacy data. 3.Context: These two fields are used to provide the correct context in which the protocol data unit (PDU) should be processed. 4.PDU: This area contains an SNMPv2c PDU.

Common Data 1.Message Version 2.Message ID 3.MaxMessageSize 4.MessageFlags 5.MessageSecurity

Security Model Data 1.General 2.EngineID 3.Engine Boots 4.Engine Time 5.UserName

Authentication Protocol 1.MD5 (Message Digest) 2.SHA (Secure Hash Algorithm)

Privacy Protocol 1.DES Key(Data Encryption Standard)

Context 1.Context Name 2.ContextID

PDU 1.MessagesFlags

Problems with SNMP: 1.SNMP is not transaction-oriented but instead offers an all-or-nothing style of execution. It is difficult to manipulate very large data sets. 2.Scalability issues where tables grow to include thousands of rows. 3.Notifications are not guaranteed to arrive at their destination. Management operations (such as get or set) can time out if the network is congested or the agent host is heavily loaded. 4.SNMP messages use the UDP protocol (best- effort datagram service).

The Different Versions of SNMP. 1.SNMPv1 2.SNMPv2c 3.SNMPv3

SNMP Applications: MIB Browsers 1.MIB browsers are specialized tools used to examine the values of MIB object instances on a given agent. A MIB browser can be a fully integerated GUI- based application or a simple text-based one.

Managed Objects: 1.Managed objects are the basic unit of exchange between an NMS and Nes. The managed objects are defined in theMIB and deployed in the network.

There is only one MIB: 1.One merit of a standard MIB is ease of extension. As new technologies are invented and deployed, the associated managed objects must be defined in new MIB modules. The latter can then be added to the standard MIB in an orderly fashion, Ex: by using enterprise specific numbers.

Some characteristics of intelligent line cards include the following 1.They can extend the lifespan of the host adding advanced functions such as SNMP and VoIP for a PABX. 2.They can take a long time to develop. 3.Operators like to extract the maximum performance from them. Ex: port bandwidth. 4.They increasingly incorporate numerous layer 1,2, and 3 protocols.

Network Elements 1.An example of an NE is an intelligent line card, which is hosted inside another system, such as a PABX, ATM/MPLS switch, or IP router Command generators create SNMP messages.

Analogy for an NMS 1.MIB modules 2.Applications-agents and managers 3.Devices-remote Nes 4.Soft objects-connections, paths, interfaces, and so on.

Analogy for an NMS 1.In the case of operating systems, some of the abstract objects are: 2.Files 3.Applications 4.Processes 5.Devices, such as hard disks and network interfaces 6.Soft objects, such as print jobs and semaphores.