Configuration of networks’ devices has become a critical requirement for operators in today's highly interoperable networks. Operators from large to small have used vendor specific mechanisms or developed their own mechanism to transfer configuration data to and from a device, and for examining device state information which may impact the configuration. Each of these mechanisms may be different in various aspects, such as configuration data exchange, user authentication, session establishment, and error responses.
5.4.1
Command-line interface (CLI)
The CLI commands allow the user to configure, manage, and troubleshoot the routers (e.g., Linux and Cisco). Linux-based ZebOS Server Routing Suite (SRS) platforms use industry-standard command line interface. The user can access to the ZebOS Server Routing Suite (SRS) CLI through a standard Telnet or SSH session. It is also possible to manage ZebOS SRS through the VTYSH daemon. HTML web user interface for administration is also provided in Zebos. The majority of configuration and monitoring of Cisco routers is via the proprietary CLI. The Cisco IOS CLI is divided into different modes. Two main modes are the user mode and the privileged EXEC mode. In user mode, only a limited subset of the commands are available such as show commands, which show the current configuration status, and clear commands, which clear counters or interfaces. To have access to all commands, a password protected privileged EXEC mode is used. From this mode, any privileged EXEC command or enter global configuration mode can be used. Using the configuration modes,
changes to the running configuration can be made. Standard MIB access is also provided via CLI for some features.
5.4.2
Configuration Management with SNMP
The ‘snmpconf’ working group is chartered to create a Best Current Practice document that outlines the most effective methods for using the SNMP Framework to accomplish configuration management. The scope of the work includes recommendations for device specific as well as network-wide (Policy) configuration. The RFC 3512 is an informational RFC to provide guidelines on how to best use the existing Internet Standard Management Framework to perform configuration management. This information is relevant to vendors that build network elements, management application developers, and those that acquire and deploy this technology in their networks.
The group is also chartered to write any MIB modules necessary to facilitate configuration management. The Internet draft [Hazewinkel 03] describes a MIB module that provides a conceptual layer between high-level "network-wide" policy definitions that effect configuration of the Diffserv subsystem and the instance-specific information that would include such details as the parameters for all the queues associated with each interface in a system. This essentially provides an interface for configuring differentiated services at a conceptually higher layer than that of the Differentiated Services MIB. The Internet draft [Waldbusser 03] defines a portion of the MIB for use with network management protocols in IP-based internets. In particular, this MIB defines objects that enable policy- based monitoring and management of SNMP infrastructures as well as a scripting language and a script execution environment.
Zebos provides SNMP management support. It supports SNMP management through IETF compliant SNMP MIBs.
Cisco uses SNMP for network management purposes, OSPF configuration management, reloading the router configuration, and so on.
• All Cisco IOS Software releases to date include SNMPv1.
• Releases from IOS Software 11.2(6)F and later have SNMPv2C support.
• Releases from IOS Software 12.0(3)T and higher have SNMPv3 support.
Some SNMP platforms can directly share data with the CiscoWorks2000 server using Common Information Model/eXtensible Markup Language (CIM/XML) methods. CIM is a common data model of an implementation-neutral schema for describing overall management information in a network/enterprise environment. CIM is comprised of a specification and a schema. The specification defines the details for integration with other management models such as SNMP MIBs or Desktop Management Task Force Management Information Files (DMTF MIFs), while the schema provides the actual model descriptions.
5.4.3
XML-based Network Configuration
The IETF ‘netconf’ Working Group is chartered to produce a protocol suitable for network configuration, with several characteristics including: to be extensible enough that vendors will provide access to all configuration data on the device using a single protocol, to use a textual data representation, that can be easily manipulated using non-specialised text manipulation tools, to have a programmatic interface, and so on.
The working group has taken the XMLCONF Configuration Protocol [Enns-xml 03] as a starting point. An Internet draft [Enns-netconf 03] is produced that defines a mechanism through which a network device can be managed. Netconf uses a remote procedure call (RPC) paradigm to define a formal API for the network device. The Netconf protocol use XML for data encoding purposes, because XML is a widely deployed standard, which is supported by a large number of applications. A client encodes an RPC in XML and sends it to a server and the server responds with a reply encoded in XML.
Most of the XML-based network configuration activities are work in progress and is at pre-standard stage. There are some products explained in the following sections that use XML-based interfaces.
5.4.3.1
XML based interfaces to network devices
The use of a standards-based XML-based API improves interoperability and integration of diverse systems by providing a common language through which network management applications and routing platforms can communicate. An API can also dramatically reduce the amount of integration work necessary to make a complex multi-vendor network manageable.
Cisco systems:
• NetFlow services capture a rich set of traffic statistics exported from routers and switches while they perform their switching functions. CNS NetFlow Collection Engine is a platform that provides fast and scalable data collection from multiple export devices exporting NetFlow data records. A XML interface (CNS/ XML) is used as a message-based application interface that allows for messaging from, and remote manageability of, the CNS NetFlow Collection Engine application. The CNS/XML interface is to send and receive configuration/control requests and responses, and unsolicited event notifications.
• CiscoWorks Data Extracting Engine is a utility that allows customers to extract data for devices managed by CiscoWorks. It extracts detailed device inventory and running configuration information in XML format from an inventory database and configuration archive.
• IP phones and call manager speak in XML format.
NextHop Technologies: NextHop Technologies' GateD family of products is a vendor-neutral, control-plane solution which provides layer 3 IP routing protocols, MPLS, virtual routing, and virtual private networking. NextHop Technologies GateD 10.0 routing software is the first IP routing source code product with an XML Routing API. This API enables vendors to quickly and easily build customised command line or web interfaces and provide users with a readily accessible script interface for managing any network device. For more information visit: www.nexthop.com
Juniper Networks: JUNOScript is an XML-based Network Management API for managing devices. XML-based JUNOScript API provides a standard integration layer between management applications and the platforms that they manage. It allows access to both operational and configuration data using a simple RPC mechanism. Sessions can be established using a variety of connection-oriented access methods. The JUNOScript API is an alternative to the existing SNMP and CLI scripting methods. Visit http://www.juniper.net/ for more information.