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../../protocols/http.rst:194
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As an illustration of HTTP/1.0, the transcript below shows a HTTP request for `http://www.ietf.org <http://www.ietf.org>`_ and the corresponding HTTP response. The HTTP request was sent using the curl_ command line tool. The `User-Agent:` header line contains more information about this client software. There is no MIME document attached to this HTTP request, and it ends with a blank line.
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../../protocols/ipv6.rst:199
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Now, consider how a router inside ``alpha.com`` would reach a host in the ``UCLouvain`` network. This router has two routes towards ``2001:6a8:3080::1``. The first one, for prefix ``2001:6a8:3080::/48`` is via the direct link between the commercial ISP and UCLouvain. The second one, for prefix ``2001:6a8::/32`` is via the Internet and Belnet. Since :rfc:`1519` when a router knows several routes towards the same destination address, it must forward packets along the route having the longest prefix length. In the case of ``2001:6a8:3080::1``, this is the route ``2001:6a8:3080::/48`` that is used to forward the packet. This forwarding rule is called the `longest prefix match` or the `more specific match`. All IP routers implement this forwarding rule.
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../../protocols/ethernet.rst:179 • ../../protocols/ethernet.rst:358
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10 Gbps
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../../protocols/tcp.rst:203
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the low order bits contain a hash value computed over the local and remote IP addresses and ports and a random secret only known to the server
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../../protocols/tls.rst:315
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The handshake is now finished. The client and the server will exchange authenticated and encrypted records. TLS defines different formats for the records depending on the cryptographic algorithms that have been negotiated for the session. A detailed discussion of these different types of records is outside the scope of this introduction. For illustration, we briefly describe one record format.
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../../bibliography.rst:357
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Zimmermann, H., `OSI Reference Model - The ISO Model of Architecture for Open Systems Interconnection <https://dx.doi.org/10.1109/TCOM.1980.1094702>`_, IEEE Transactions on Communications, vol. 28, no. 4, April 1980, pp. 425 - 432.
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../../glossary.rst:132
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IANA
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../../principles/reliability.rst:224
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0111111001111101001111110
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../../principles/transport.rst:204
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the `connectionless network layer service` may discard SDUs
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../../principles/security.rst:671
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The solution described above works provided that Bob and Alice know their respective public keys before communicating. Otherwise, the protocol is not secure against man-in-the-middle attackers. Consider Mallory sitting in the middle between Alice and Bob and assume that neither Alice nor Bob knows the other's public key.
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../../exercises/ipv6.rst:580
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IPMininet_ simplifies the creation of the network topology by providing a simple API. For this, you simply need to declare a class that extends the ``IPTopo`` class.
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../../exercises/routing-protocols.rst:845
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IPMininet_ also allows to explore the dynamics of BGP by looking at the packets that the routers exchange. For this, we slightly modify the example above and add delays to the interdomain links as follows.
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../../exercises/tcp-2.rst:775
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Let us now explore the impact of congestion on the slow-start and congestion avoidance mechanisms. Consider the scenario below. For graphical reasons, it is not possible anymore to show information about the segments on the graph, but you can easily infer them.
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../../protocols/bgp.rst:258
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Another example of frequently used `import filters` are the filters that Internet Service Providers use to ignore bogon routes. In the ISP community, a bogon route is a route that should not be advertised on the global Internet. Typical examples include the documentation IPv6 prefix (`2001:db8::/32` used for most examples in this book), the loopback address (`::1/128`) or the IPv6 prefixes that have not yet been allocated by IANA. A well managed BGP router should ensure that it never advertises bogons on the global Internet. Detailed information about these bogons may be found in [IMHM2013]_.
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../../protocols/email.rst:234
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B
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../../protocols/ethernet.rst:263
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The pseudo-code below details how an Ethernet switch forwards Ethernet frames. It first updates its `MAC address table` with the source address of the frame. The `MAC address table` used by some switches also contains a timestamp that is updated each time a frame is received from each known source address. This timestamp is used to remove from the `MAC address table` entries that have not been active during the last `n` minutes. This limits the growth of the `MAC address table`, but also allows hosts to move from one port to another. The switch uses its `MAC address table` to forward the received unicast frame. If there is an entry for the frame's destination address in the `MAC address table`, the frame is forwarded selectively on the port listed in this entry. Otherwise, the switch does not know how to reach the destination address and it must forward the frame on all its ports except the port from which the frame has been received. This ensures that the frame will reach its destination, at the expense of some unnecessary transmissions. These unnecessary transmissions will only last until the destination has sent its first frame. Multicast and Broadcast frames are also forwarded in a similar way.
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../../protocols/http.rst:203
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The HTTP response indicates the version of the server software used with the modules included. The `Last-Modified:` header indicates that the requested document was modified about one week before the request. A HTML document (not shown) is attached to the response. Note the blank line between the header of the HTTP response and the attached MIME document. The `Server:` header line has been truncated in this output.
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../../protocols/ipv6.rst:201
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To understand the `longest prefix match` forwarding, consider the IPv6 routing below.
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../../protocols/ethernet.rst:179
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Optical fiber but also Category 6 UTP
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../../protocols/tcp.rst:205
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The advantage of the `SYN cookies`_ is that by using them, the server does not need to create a :term:`TCB` upon reception of the `SYN` segment and can still check the returned `ACK` segment by recomputing the `SYN cookie`. The main disadvantage is that they are not fully compatible with the TCP options. This is why they are not enabled by default on a typical system.
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