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34 ../../principles/reliability.rst:152
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the `Physical layer service` may change, e.g. due to electromagnetic interference, the value of a bit being transmitted 119/10000 · 119
34 ../../principles/sharing.rst:226
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — When the network load is low, buffer occupancy and link utilization are low. The buffers on the network nodes are mainly used to absorb very short bursts of packets, but on average the traffic demand is lower than the network capacity. If the demand increases, the average buffer occupancy will increase as well. Measurements have shown that the total throughput increases as well. If the buffer occupancy is zero or very low, transmission opportunities on network links can be missed. This is not the case when the buffer occupancy is small but non zero. However, if the buffer occupancy continues to increase, the buffer becomes overloaded and the throughput does not increase anymore. When the buffer occupancy is close to the maximum, the throughput may decrease. This drop in throughput can be caused by excessive retransmissions of reliable protocols that incorrectly assume that previously sent packets have been lost while they are still waiting in the buffer. The network delay on the other hand increases with the buffer occupancy. In practice, a good operating point for a network buffer is a low occupancy to achieve high link utilization and also low delay for interactive applications. 1199/10000 · 1199
34 ../../principles/transport.rst:87
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `Bell`: `0000111b` 18/10000 · 18
34 ../../principles/security.rst:375
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A public key cryptographic scheme is a combination of two functions : 69/10000 · 69
34 ../../exercises/dns.rst:113
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — On a Linux machine, the *Description* section of the `dig` man page tells you where `dig` finds the list of nameservers to query. 129/10000 · 129
34 ../../exercises/ipv6.rst:330
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The students have configured the following forwarding tables on these six routers. 82/10000 · 82
34 ../../exercises/routing-protocols.rst:380
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — To explore the configuration of BGP, let us consider a network that contains three ASes: ``AS1``, ``AS2`` and ``AS3``. To simplify the tests, we identify one host inside each of these ASes. 190/10000 · 190
34 ../../exercises/tcp-2.rst:261
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Let us first use packetdrill_ to explore the evolution of the TCP retransmission timeout. The value of this timeout is set based on the measured round-trip-time and its variance. When the retransmission timer expires, TCP doubles the retransmission timer. This exponential backoff mechanism is important to ensure that TCP slowdowns during very severe congestion periods. We use the ``tcpi_rto`` variable from ``TCP_INFO`` to track the evolution of the retransmission timer. This script is available from :download:`/exercises/packetdrill_scripts/rto.pkt`. 556/10000 · 556
34 ../../protocols/bgp.rst:116
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A BGP peering session between two directly connected routers 60/10000 · 60
34 ../../protocols/congestion.rst:189
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Thanks to its congestion control scheme, TCP adapts its transmission rate to the losses that occur in the network. Intuitively, the TCP transmission rate decreases when the percentage of losses increases. Researchers have proposed detailed models that allow the prediction of the throughput of a TCP connection when losses occur [MSMO1997]_ . To have some intuition about the factors that affect the performance of TCP, let us consider a very simple model. Its assumptions are not completely realistic, but it gives us good intuition without requiring complex mathematics. 572/10000 · 572
34 ../../protocols/email.rst:178
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Inside the email header, the `Content-Type:` header line indicates how the MIME email message is structured. :rfc:`2046` defines the utilization of this header line. The two most common structures for MIME messages are : 220/10000 · 220
34 ../../protocols/ethernet.rst:174
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 10Base-F 8/10000 · 8
34 ../../protocols/http.rst:146
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the `GET` method is the most popular one. It is used to retrieve a document from a server. The `GET` method is encoded as `GET` followed by the path of the URI of the requested document and the version of HTTP used by the client. For example, to retrieve the http://www.w3.org/MarkUp/ URI, a client must open a TCP connection on port `80` with host `www.w3.org` and send a HTTP request containing the following line: 416/10000 · 416
34 ../../protocols/http2.rst:234
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — HTTP/2.0 includes much more than what we have covered in this short introduction. There is for example a `Ping` frame that allows measuring the round-trip-time between a client and a server or the `GoAway` frame that indicates the termination of an HTTP/2.0 session. This frame contains an error code that indicates why the session has been terminated. Several error codes are defined in :rfc:`7540`, including `ENHANCE_YOUR_CALM` that is used to indicate that the other endpoint exhibits an behavior that could cause excessive load. 533/10000 · 533
34 ../../protocols/ipv6.rst:122
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — ``0:0:0:0:0:0:0:0`` is represented as ``::`` 44/10000 · 44
34 ../../protocols/ethernet.rst:109
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Several physical layers have been defined for Ethernet networks. The first physical layer, usually called 10Base5, provided 10 Mbps over a thick coaxial cable. The characteristics of the cable and the transceivers that were used then enabled the utilization of 500 meter long segments. A 10Base5 network can also include repeaters between segments. 348/10000 · 348
34 ../../protocols/routing.rst:103
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `2001:db8:aaaa:0000::/64` at a distance of `1` and `2001:db8:aaaa:0001::/64` at a distance of `2` from `RA` 107/10000 · 107
34 ../../protocols/rpc.rst:120
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `code`: a number that indicates the type of error. Several error codes are defined in [JSON-RPC2]_. For example, `-32700` indicates an error in parsing the request, `-32602` indicates invalid parameters and `-32601` indicates that the method could not be found on the server. Other error codes are listed in [JSON-RPC2]_. 321/10000 · 321
34 ../../protocols/ssh.rst:248
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `ssh` is one example of a protocol that uses Message Authentication Codes (MAC) to authenticates the messages that are sent. A naive implementation of such a MAC would be to simply use a hash function like SHA-1. However, such a construction would not be safe from a security viewpoint. Internet protocols usually rely on the HMAC construction defined in :rfc:`2104`. It works with any hash function (`H`) and a key (`K`). As an example, let us consider HMAC with the SHA-1 hash function. SHA-1 uses 20 bytes blocks and the block size will play an important role in the operation of HMAC. We first require the key to be as long as the block size. Since this key is the output of the key generation algorithm, this is one parameter of this algorithm. 749/10000 · 749
34 ../../protocols/tcp.rst:113 • ../../protocols/tcp.rst:118
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — the `SYN` flag set 18/10000 · 18