BGP4, exercise 1

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BGP-4, exercise 1
AS2
AS3
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AS1
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BGP-4, exercise 1 - BGP Stub

• AS1 should allocate IP addresses for all inter-AS
  links
• Use loopback0 address as update-source!
• Create BGP link between your interconnect router
  and AS1
• After your BGP connection is up, examine your
  routing table. Have any new entries appeared?
• Configure your router to announce via BGP your
  local subnets to your peer in AS1. Have any new
  entries appeared in your routing table? If so,
  what are the new entries?
• Break the physical link between your group and
  AS1. How long does it take for the BGP connection
  to go down? How long until the routes learned
  from your BGP peer are removed from your routing
  tables?
• Restore the link. How long does it take before
  all routes are distributed to all routers again?

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BGP-4, exercise 2
AS2
AS3
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AS1
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BGP-4, exercise 2 - BGP Transit

• Establish a link between AS2 and AS3. AS2 should
  allocate address space for inter-AS link,
• AS2 will now become a transit provider by
  configuring its internal routers to pass traffic
  from one customer to another.
• AS2 must set up an IBGP connection between all
  routers
• What AS paths can you see in the routing table?
  Why?
• Break the link from AS1 to AS2. How long does it
  take before all routers in AS2 detect the link
  failure and remove all AS1 routes from their
  tables?
• Connect the link between AS1 and AS2. Break the
  link between AS2 and AS3. Is there a full
  connectivity? Explain!
• Reconnect the link!

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BGP-4, exercise 3
AS2
AS3
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AS1
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BGP-4, exercise 3, Multihomed

• Reconnect AS1 according to the picture.
• AS1 and AS3 become transit providers.
• Check the BGP routing tables. Any changes?
• Transform AS1 and AS2 from a transit provider to
  a multihomed customer. How can this be achieved?
• Configure AS1 and AS2 to prefer the connection
  via AS3 over the direct link. What mechanism are
  you going to use?
• Make backup arrangements between AS1 and AS2.