XML-based Network Management

1
XML-based Network Management

• Rob Enns
• rpe_at_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

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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

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XML Elements

• Six main constructs
• Open tags lttaggt
• Close tags lt/taggt
• Data lttaggtdatalt/taggt
• Empty tags lttag/gt
• Attributes lttag foobar googar/gt
• Namespaces

lthomegt ltaddressgt123 Main Streetlt/addressgt
ltnetwork xmlnsns2my.identifying.stringgt
ltns2addressgt10.0.0.1lt/ns2addressgt
lt/networkgt lt/homegt
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XML Example

• lt?xml version"1.0" encoding"UTF-8"?gt
• ltroutegt
• ltdestinationgt10.3.1.1/32lt/destinationgt
  
• ltroute-entrygt
• ltcurrent-active/gt
• ltprotocol-namegtBGPlt/protocol-namegt
  
• ltpreferencegt170lt/preferencegt
• ltage seconds"1749"gt002909lt/agegt
  
• ltlocal-preferencegt100lt/local-prefe
  rencegt
• ltlearned-fromgt10.17.136.2lt/learned
  -fromgt
• ltas-pathgt1403 170 39 Ilt/as-pathgt
• ltnhgt
• ltselected-next-hop/gt
• lttogt192.168.1.254lt/togt
• ltviagtge-0/0/0.0lt/viagt
• lt/nhgt
• lt/route-entrygt
• lt/routegt

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Advantages of XML

• Handles forward and backward compatibility
• Widely available tools
• Widely implemented standard
• http//www.w3c.org/xml

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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

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XSL

• XML Stylesheet Language
• Originally intended for rendering XML
• Powerful enough for generic transformations
• Two branches of the technology
• XSLT XSL Transformations
• XML-gtXML 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

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XSL Functionality
XSLT Stylesheet
ltTDgt MTU ltxslvalue-of./gt lt/TDgt
XML Input Document
XML Output Document
ltmtugt 1500 lt/mtugt
XSLT Processor
ltTDgt MTU 1500 lt/TDgt
XSLT can make XML, XHTML, Text, SVG, XSLT
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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-n
  umber
• Select every chassis component with a temperature
  attribute greater than 40 degrees
• chassis-module_at_temperature gt 40
• Get the status of power supply B
• chassis-modulename"Power Supply B"/status

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Using XML for Network Management

• Network Monitoring
• Device Configuration
• Network Provisioning
• Fault diagnosis

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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

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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
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Device Configuration

• Configuration is exposed in XML elements
• For example

ltconfigurationgt ltprotocolsgt ltbgpgt
ltgroupgt
ltnamegtlocallt/namegt ltneighborgt
ltnamegt10.0.0.1lt/namegt
ltlocal-addressgt10.0.0.2lt/local-addre
ssgt lt/neighborgt
lt/groupgt lt/bgpgt lt/protocolsgt lt/configu
rationgt
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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

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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

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

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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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Thank you!

• http//www.juniper.net