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../../exercises/ipv6.rst:991
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When the :manpage:`ping6(8)` is executed, it sends ICMPv6 echo request messages with increasing sequence numbers.
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../../protocols/bgp.rst:400
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`AS3` sends `U(2001:db8:1234/48,AS3:AS1)` to `AS4` and, at the same time, `AS4` sends `U(2001:db8:1234/48,AS4:AS1)`. `AS3` prefers the route via `AS4` and thus sends `W(2001:db8:1234/48)` to `AS4`. In the mean time, `AS4` prefers the route via `AS3` and thus sends `W(2001:db8:1234/48)` to `AS3`. Upon reception of the `BGP Withdraws`, `AS3` and `AS4` only know the direct route towards `2001:db8:1234/48`. `AS3` (resp. `AS4`) sends `U(2001:db8:1234/48,AS3:AS1)` (resp. `U(2001:db8:1234/48,AS4:AS1)`) to `AS4` (resp. `AS3`). `AS3` and `AS4` could in theory continue to exchange BGP messages for ever. In practice, one of them sends one message faster than the other and BGP converges.
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../../protocols/email.rst:246
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Y
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../../protocols/ethernet.rst:377
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Designated
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../../protocols/ipv6.rst:369
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The last two headers are used to add security above IPv6 and implement IPSec. They are described in :rfc:`2402` and :rfc:`2406` and are outside the scope of this document.
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../../protocols/ethernet.rst:359
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../../protocols/tcp.rst:309
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in TCP/IP networks, a large fraction of the packets are TCP segments that contain only an acknowledgment. These packets usually account for 40-50% of the packets passing through the studied link
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../../glossary.rst:288
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A telephone line that is permanently available between two endpoints.
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../../principles/network.rst:414 • ../../principles/network.rst:424
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->R5
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../../principles/reliability.rst:389
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Reliable data transfer on top of an imperfect link
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../../principles/sharing.rst:475
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Both hosts defer their retransmission and a new collision occurs
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../../principles/security.rst:1006
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This prevents the attack mentioned above since Mallory cannot create a fake certificate and cannot sign a value by using Bob's private key. Given the risk of man-in-the-middle attacks, the Diffie-Hellman key exchange mechanism should never be used without authentication.
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../../exercises/ipv6.rst:995
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The :manpage:`traceroute6(8)` software is very useful to debug network problems. It sends a series of UDP segments encapsulated inside IP packets with increasing values of the HopLimit. The first packet has a HotLimit and the first router on the path returns an ICMPv6 HopLimit exceeded message.
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../../protocols/bgp.rst:402
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The example above has shown that the routes selected by BGP routers may sometimes depend on the ordering of the BGP messages that are exchanged. Other similar scenarios may be found in :rfc:`4264`.
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../../protocols/email.rst:246
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../../protocols/ethernet.rst:382
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To illustrate the operation of the `Spanning Tree Protocol`, let us consider the simple network topology in the figure below.
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../../protocols/ipv6.rst:371
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The `Hop-by-Hop Options` header was designed to make IPv6 easily extensible. In theory, this option could be used to define new fields that were not foreseen when IPv6 was designed. It is intended to be processed by both routers and hosts. Deploying an extension to a network protocol can be difficult in practice since some nodes already support the extensions while others still use the old version and do not understand the extension. To deal with this issue, the IPv6 designers opted for a Type-Length-Value encoding of these IPv6 options. The `Hop-by-Hop Options` header is encoded as shown below.
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../../protocols/ethernet.rst:362
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The `Spanning Tree Protocol` uses its own terminology that we illustrate in the figure above. A switch port can be in three different states : `Root`, `Designated` and `Blocked`. All the ports of the `root` switch are in the `Designated` state. The state of the ports on the other switches is determined based on the `BPDU` received on each port.
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../../protocols/tcp.rst:310
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in TCP/IP networks, most of the bytes are exchanged in long packets, usually packets containing about 1440 bytes of payload which is the default MSS for hosts attached to an Ethernet network, the most popular type of LAN
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../../glossary.rst:30
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MAN
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