XML-based Network Management

1. XML-based Network Management Rob Enns rpe@juniper.net

2. 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

3. 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 • http://www.w3c.org/xml

4. 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

5. XML Elements • Six main constructs • Open tags: <tag> • Close tags: </tag> • Data: <tag>data</tag> • Empty tags: <tag/> • Attributes: <tag foo=“bar” goo=“gar”/> • Namespaces: <home> <address>123 Main Street</address> <network xmlns:ns2=“my.identifying.string”> <ns2:address>10.0.0.1</ns2:address> </network> </home>

6. XML Example <?xml version="1.0" encoding="UTF-8"?> <route> <destination>10.3.1.1/32</destination> <route-entry> <current-active/> <protocol-name>BGP</protocol-name> <preference>170</preference> <ageseconds="1749">00:29:09</age> <local-preference>100</local-preference> <learned-from>10.17.136.2</learned-from> <as-path>1403 170 39 I</as-path> <nh> <selected-next-hop/> <to>192.168.1.254</to> <via>ge-0/0/0.0</via> </nh> </route-entry> </route>

7. Advantages of XML • Handles forward and backward compatibility • Widely available tools • Widely implemented standard • http://www.w3c.org/xml

8. 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

9. 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

10. XSL Functionality XSLT Stylesheet <TD> MTU: <xsl:value-of=“.”/> </TD> XML Input Document XML Output Document <mtu> 1500 </mtu> XSLT Processor <TD> MTU: 1500 </TD> XSLT can make: XML, XHTML, Text, SVG, XSLT

11. 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 • chassis-module[@temperature &gt; 40] • Get the status of power supply B • chassis-module[name="Power Supply B"]/status

12. Using XML for Network Management • Network Monitoring • Device Configuration • Network Provisioning • Fault diagnosis

13. 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) • Email (XSLT) • Report PDF (XSL-FO) • Example: Collecting hardware inventory

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

15. Device Configuration • Configuration is exposed in XML elements • For example: <configuration> <protocols> <bgp> <group> <name>local</name> <neighbor> <name>10.0.0.1</name> <local-address>10.0.0.2</local-address> </neighbor> </group> </bgp> </protocols> </configuration>

16. 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

17. 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

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

19. 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

20. 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 • XML’s 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.

21. Thank you! http://www.juniper.net