Configuring BGP routing protocol #router bgp {AS no.}  #network {network ID} mask [subnet mask] – When you dont put mask the router will assume default classfull mask  #neighbor {IP address} remote-as {AS No.} BEWARE!! In BGP there is rule that states: router looks exactly what you type in network command with the mask also! If  Full Article…

In BGP there are two loop prevention mechanism: for EBGP there is AS-Path attribute which states that router will drop BGP advertisement when it sees it own AS number in AS path attribute for IBGP there is split horizon rule which states that update sent by one IBGP neighbor should be not send to another  Full Article…

Active neighbor It may happen that your neighborship is in state Active or Idle. It means that router has sent an open packet and is waiting for response. There could be several reasons for that: neighbor is peering with a wrong IP address neighbor doesnt have neighbor statement for this router AS number is missconfigured Interface  Full Article…

BGP supports authentication mechanism using MD5 mechanism. When authentication is enabled every TCP segment belonging to BGP session is verified and accepted only if the authentication match. If authentication fails, the BGP relationship is not established. You may configure BGP authentication with the command #neighbor {IP address | peer group name} password {XXX}

Peer groups simplifies the configuration by allowing to apply same policy rules to more neighbors. Updates are generated once per peer group. You configure new peer group by following commands: #neighbor {name of peer group} peer-group – you create peer group with its name #neighbor {name of peer group} remote-as {number} – you set the  Full Article…