XML-based Network Management Rob Enns

Introduction Routers are complex devices that are hard to manage remotely Traditional management methods are SNMP and expect, their strengths and weaknesses are well-known Operators and network management software vendors demand a secure, stable method to manage routers Want network-oriented solutions, not single-box ones XML is an alternative with exciting possibilities

XML Extensible Markup Language XML is a generally self-describing data format Application reads data, parses it, and knows exactly what each constituent part of the data means An XML document is a text file with structure Easy to understand Easy to parse Easy to debug Widely implemented standard

Why XML? Network devices are good at generating large amounts of hierarchical data Device configurations Routing tables Interface hierarchies Billing records XML is good at describing hierarchical data in a standard way

XML Elements Six main constructs Open tags: Close tags: Data: data Empty tags: Attributes: Namespaces: 123 Main Street

/32 BGP :29: I ge-0/0/0.0 XML Example

Advantages of XML Handles forward and backward compatibility Widely available tools Widely implemented standard

DTDs and XML Schemas XML data definition tools Document Type Definitions (DTDs) Lists the elements that may appear in an XML document and their relationships to one another XML Schemas Defines content and semantics in addition to element relationships Simple and complex data types, value ranges, match expressions, documentation

XSL XML Stylesheet Language Originally intended for rendering XML Powerful enough for generic transformations Two branches of the technology XSLT – XSL Transformations XML->XML transformations Add additional information Remove uninteresting elements or attributes Rearrange hierarchies, sort elements, lots of party tricks XSL-FO – XSL Formating Objects Render XML into XHTML or PDF

XSL Functionality XSLT Processor XSLT Stylesheet XML Input Document XML Output Document XSLT can make: XML, XHTML, Text, SVG, XSLT MTU: MTU:

XPath A standard for describing parts of XML documents Uses Unix-like path expressions Basic expression and function support Used by XSL Select the serial number of every chassis component /chassis-inventory/chassis/chassis-module/serial-number Select every chassis component with a temperature attribute greater than 40 degrees > 40] Get the status of power supply B chassis-module[name="Power Supply B"]/status

Using XML for Network Management Network Monitoring Device Configuration Network Provisioning Fault diagnosis

Network Monitoring Applications periodically fetch operational content Compare against historical data using XML diff tools, or transform data into a more appropriate format using XSLT Use XSL to render output Web page (XSLT) (XSLT) Report PDF (XSL-FO) Example: Collecting hardware inventory

Hardware Inventory Inventory DB Router A Router Z Retrieve inventory data from network Transform data into format required by inventory DB Add data to inventory DB XSL Transformation

Device Configuration Configuration is exposed in XML elements For example: local

Device Configuration Represent device configurations in XML Configurations become malleable data, can be manipulated using standard tools Add/delete/change configuration using XSL transformations Store and retrieve configuration from an XML database

Network Provisioning Avoid writing multiple vendor-specific configuration parsers Use XSLT to translate from vendor-neutral configuration to a vendor-specific configuration for each device XML Schemas can provide data types, value ranges, regex matches, help information for vendor configuration Enables provisioning tools to partially validate configuration before uploading to device

Network Provisioning Router(s) Customer DB Interface DB Policy DB XSL Transformation Device-specific Configuration Vendor- independent configuration

Diagnosing Faults Everyone has 5 commands to run when logging on to a sick router Diagnose problems with network by running XSL scripts over XML output XSL is a powerful tool Inspect results from multiple commands Discard normal output Focus on abnormal situations Use SVG (Scalable Vector Graphics (XML)) to graph historical values for data visualization Target multiple routers

Summary Choosing XML simplifies application development Widely available tools and information Easy to understand text format Larger talent pool of engineers Offers a reliable alternative to Expect scripts XMLs self-describing nature prevents problems with variations in CLI output Enhances Interoperability XML is a standard method of exchanging information between programs Adopted by many industries – eCommerce, databases, networking, etc.

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