Configuring Aggregation: Cisco IOS

• ISP has 101.10.0.0/19 address block

• To put into BGP as an aggregate:

  router bgp 100
  
  network 101.10.0.0 mask 255.255.224.0
  ip route 101.10.0.0 255.255.224.0 null0

• The static route is a “pull up” route

  • more specific prefixes within this address block ensure connectivity to ISP’s customers
  • “longest match lookup”

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