Exit Zen
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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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../../principles/network.rst:417
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Since a packet received with `label=1` must be forwarded to `R5` with `label=1`, `R2`'s `label forwarding table` could contain :
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../../principles/reliability.rst:391
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The datalink layer must deal with the transmission errors. In practice, we mainly have to deal with two types of errors in the datalink layer :
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../../principles/transport.rst:571
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To support the connection-oriented service, the transport layer needs to include several mechanisms to enrich the connectionless network-layer service. We discuss these mechanisms in the following sections.
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../../principles/sharing.rst:477
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In the second and third cases, both hosts have flipped different coins. The delay chosen by the host that defers its retransmission should be long enough to ensure that its retransmission will not collide with the immediate retransmission of the other host. However the delay should not be longer than the time necessary to avoid the collision, because if both hosts decide to defer their transmission, the network will be idle during this delay. The `slot time` is the optimal delay since it is the shortest delay that ensures that the first host will be able to retransmit its frame completely without any collision.
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../../principles/security.rst:1015
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Footnotes
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../../exercises/ipv6.rst:999
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When :manpage:`traceroute6(8)` sends UDP segments, it uses the UDP source port as a way to remember the target hop for this specific UDP segment.
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../../protocols/bgp.rst:404
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From an operational perspective, the above configuration is annoying since the network operators cannot easily predict which paths are chosen. Unfortunately, there are even more annoying BGP configurations. For example, let us consider the configuration below which is often named `Bad Gadget` [GW1999]_
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../../protocols/email.rst:246
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p
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../../protocols/ethernet.rst:389
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A simple Spanning tree computed in a switched Ethernet network
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