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Forum Replies

  1. Hi Rene,

    I have some vague about full update and partial update ?
    Do you mean :-
    1 - The full update always send using unicast after neighbor adjacency formed ?
    2 - The partial update always send using multicast when there is a change in the topology ? and if we use static neighbors the partial update will be sent using unicast ? that’s right ?
    If there is wrong correct me please ?


  2. Hi Hussein,

    When you use static neighbors, it’s 100% unicast. Here’s a capture where you can see this:


    Here’s an example where we use the default neighbor discovery (multicast):


    The initial (full) update messages are sent using unicast, the other update messages (partial updates) are sent with multicast. These are used for things like metric changes.


  3. Hello Clement.

    There are differing opinions as to how many and what type of EIGRP packets exist. Some refer to five, others to six. Some group Request packets and Query packets together. Some group ACK and Hello packets together (since ACK is basically an empty hello packet). Some just don’t mention Request packets. It really depends on who you ask.

    Cisco’s official documentation states that there are five packet types:

    • Hello/Acks
    • Updates
    • Queries
    • Replies
    • Requests

    Although Cisco’s official CCNA curriculum gives the following list:

    • Hello
    • Acknowledgements
    • Updates
    • Queries
    • Replies

    In any case, a request packet is similar to a query packet, except for the fact that query packets are sent reliably while request packets are not. Request packets can be both unicast or multicast and are initially sent when an EIGRP router joins an EIGRP AS and requests information from neighbours.

    Cisco also says that these packets are used in route server applications. A route server is a troubleshooting device within an Autonomous System that is able to view the IP routing tables of all participating routers. It can be used to determine routing faults and to correct routing malfunctions. So request packets are used for such applications.

    The truth is it is not very clear, but I hope that this makes it somewhat clearer for you.

    I hope this has been helpful!


  4. Hi Heng,

    You can see this with a quick Wireshark capture: eigrp-query-reply.pcapng

    These are two routers using IP addresses and

    Once loses a route (, it sends the query to first responds to the query with an ACK. Wireshark shows the ACK as Hello (5), don’t let this confuse you…this happens because the EIGRP hello and ACK packet both share the same opcode. responds with a reply, which is ACKed by as well.

    I hope this helps!


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