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  1. I guess if the person spoofing is capable of spoofing a TTL of 2, they are also capable of spooing a TTL of 256 which (with the default config) would effectively override this safety mechanism in this scenario :slight_smile:

    Unless the TTL is an 8 bit field, so 255 is the highest value!

  2. Hello Chris

    Yes, you are correct that the TTL field is an 8 bit field, so the highest value can be 255.

    I hope this has been helpful!


  3. Hello again Chris.

    You must remember that the value configured in the ttl-security all-interfaces hops command is the number of allowed hops and not the actual value of the TTL field. The value is essentially a threshold.

    The default value is actually 0. This means that it will accept any values of TTL equal to or greater than 255-0. Since routing decrements the TTL by one, this means that only OSPF packets from directly connected devices will be accepted.

    If this threshold is configured at 100 hops, then only packets with a TTL higher than 255-100 = 155 will be accepted. That means that packets with a TTL within the range of 155 to the maximum of 255 will be accepted.

    I hope this has been helpful!


  4. Hi Rene,
    Hopefully you are doing good…

    I have one question When i am going through you CCIE R&S Written Table of Contents here why 3.6e:Path Preference & 3.6f:Operations not showing anything when i am trying to click there no page is opening so are you want to add any content there or its mistake by you? then 3.6g:Convergence and Scalability having content because when i clicking the + button the content is coming.

    For your reference i attached the screenshot as well.

    Thanks & Regards,

  5. Hi Rene,
    Thanks for replying … if you add any thing there defenately I will go through the point…

    Thanks & Regards,

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