BGP neighbors are not in an established state

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Wed, 07/22/2009 - 19:36
Jun 18th, 2009
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Core Issue

These issues may prevent the Border Gateway Protocol (BGP) neighbors from being established:


  • The neighbor IP address or Autonomous System (AS) number is incorrect.
  • In a non-directly connected neighbor, no routes to the neighbor IP address exist, or the default route (0.0.0.0/0) is used to reach the peer.
  • The neighbor update-source command is missing under the BGP.
  • The typing error results in the wrong IP address or as-number in the neighbor statement. Check your configurations.
  • The unicast is broken due to one of these reasons:


    • The wrong Virtual Circuit (VC) maps in an ATM or Frame Relay environment and in a highly redundant network.
    • The Access Control List (ACL) blocks the unicast or Transmission Control Protocol (TCP) packet at port 179.
    • The Network Address Translation (NAT) runs on the router and translates the unicast packet.
    • Layer 2 is down.

Resolution

To resolve this issue, refer to Why Do BGP Neighbors Toggle Between Idle, Connect, and Active States?.

show ip bgp neighbors {neighbor  address}

State is active

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