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The second Round is Selection where BGP Best… The first round is Rejection where any route matching certain condition will be rejected. There are 3 (Rejection, Selection, Tie-Break) rounds of BGP Path Selection which involve 18 different steps. In this discussion we will dive into the BGP Path Selection Algorithm. Tags bgp-fsm bgp-input-events bgp-message-types bgp-stuck-in-active BGP is a Transport Layer Protocol, hence TCP provides fragmentation, acknowledgement, sequencing… Before establishing BGP Peer Connection, two neighbor must perform TCP Three-Way-Handshake and open a connection to Port number 179. In this tutorial we will discuss about different message types of BGP, BGP Peer Connection, BGP Finite State Machine. Tags bgp bgp-fsm bgp-stuck-in-active bgp-stuck-in-idle Refer the below flow chart where it explains… It's a Cisco proprietary and use to enable fast DR recovery in a multi-access network.īGP Neighbor States – IDLE – CONNECT – ACTIVE From this explanation we might understand that a BGP process remains in ACTIVE state is due to TRANSPORT ERROR means the BGP process is unable to initiate a TCP Connection to the Neighbor.
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Remembering old DR is an optimization of DR/BDR election process. Introduction - Preemption vs Remember OLD DR. Tags backup area isolated area multiarea adjacency ospf partitioned area Tags external loop prevention inter area loop prevention ospf loop prevention Tags external-lsa forwarding-address ospf
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Tags N/P Bit nssa nssa-area ospf p-bit Propagate Bit Its is called propagate bit, when set to 0(zero/Unset), NSSA ABR doesn't translate the Type-7 to Type-5, otherwise the NSSA ABR translate the Tyep-7 to Type-5 Tags dhcp dhcp ack dhcp discover dhcp lease dhcp offer dhcp reuest dhcp transaction id dhcpdecline dhcpinform dhcpnak dhcprelease doraĪ NSSA ABR Translate Type-7 LAS to Type-5 LSA based on the value of P-Bit. Clients/Hosts send request to DHCP servers… DHCP essentially uses BOOTP message format added with some options filed using UDP(Port 67 & 68). It is an extension of BOOTP protocol and backward compatibility is maintained. DHCP is a client/server protocol used to assign configuration(ip, gateway, dns, options etc.) to hosts dynamically.
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