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148 ../../principles/reliability.rst:502
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The simplest error detection scheme is the checksum. A checksum is basically an arithmetic sum of all the bytes that a frame is composed of. There are different types of checksums. For example, an eight bit checksum can be computed as the arithmetic sum of all the bytes of (both the header and trailer of) the frame. The checksum is computed by the sender before sending the frame and the receiver verifies the checksum upon frame reception. The receiver discards frames received with an invalid checksum. Checksums can be easily implemented in software, but their error detection capabilities are limited. Cyclical Redundancy Checks (CRC) have better error detection capabilities [SGP98]_, but require more CPU when implemented in software. 742/10000 · 742
148 ../../principles/transport.rst:860
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Connection release 18/10000 · 18
148 ../../principles/sharing.rst:933
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The congestion control scheme must be `efficient`. The bottleneck link is usually both a shared and an expensive resource. Usually, bottleneck links are wide area links that are much more expensive to upgrade than the local area networks. The congestion control scheme should ensure that such links are efficiently used. Mathematically, the control scheme should ensure that :math:`\forall{t} \sum{r_i(t)} \approx R`. 417/10000 · 417
148 ../../protocols/email.rst:258
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — e 1/10000 · 1
148 ../../protocols/ipv6.rst:496
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Note that the reassembly algorithm must deal with the unreliability of the IP network. This implies that a fragment may be duplicated or a fragment may never reach the destination. The destination can easily detect fragment duplication thanks to the `Fragment Offset`. To deal with fragment losses, the reassembly algorithm must bind the time during which the fragments of a packet are stored in its buffer while the packet is being reassembled. This can be implemented by starting a timer when the first fragment of a packet is received. If the packet has not been reassembled upon expiration of the timer, all fragments are discarded and the packet is considered to be lost. 676/10000 · 676
148 ../../protocols/wifi.rst:23
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 23 Mbps 7/10000 · 7
148 ../../protocols/tcp.rst:447
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The default go-back-n retransmission strategy was defined in :rfc:`793`. When the retransmission timer expires, TCP retransmits the first unacknowledged segment (i.e. the one having sequence number `snd.una`). After each expiration of the retransmission timeout, :rfc:`2988` recommends to double the value of the retransmission timeout. This is called an `exponential backoff`. This doubling of the retransmission timeout after a retransmission was included in TCP to deal with issues such as network/receiver overload and incorrect initial estimations of the retransmission timeout. If the same segment is retransmitted several times, the retransmission timeout is doubled after every retransmission until it reaches a configured maximum. :rfc:`2988` suggests a maximum retransmission timeout of at least 60 seconds. Once the retransmission timeout reaches this configured maximum, the remote host is considered to be unreachable and the TCP connection is closed. 964/10000 · 964
148 ../../bibliography.rst:360
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — White, R., Mc Pherson, D., Srihari, S., `Practical BGP <http://books.google.com/books?id=9OlSAAAAMAAJ>`_, Addison-Wesley, 2004 126/10000 · 126
149 ../../glossary.rst:125
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The round-trip-time (RTT) is the delay between the transmission of a segment and the reception of the corresponding acknowledgment in a transport protocol. 155/10000 · 155
149 ../../principles/dv.rst:212
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — `E` sends its distance vector :math:`[E=0,A=2,C=1,D=1,B=1]` to `D`, `B` and `C`. `D` learns a route towards `B`. `C` and `B` learn a route towards `A`. 151/10000 · 151
149 ../../principles/transport.rst:864
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — When we discussed the connection-oriented service, we mentioned that there are two types of connection releases : `abrupt release` and `graceful release`. 154/10000 · 154
149 ../../principles/sharing.rst:934
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The congestion control scheme should be `fair`. Most congestion schemes aim at achieving `max-min fairness`. An allocation of transmission rates to sources is said to be `max-min fair` if : 189/10000 · 189
149 ../../protocols/email.rst:258
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 47 2/10000 · 2
149 ../../protocols/ipv6.rst:499
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Header compression on low bandwidth links 41/10000 · 41
149 ../../protocols/wifi.rst:23 • ../../protocols/wifi.rst:25
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 54 Mbps 7/10000 · 7
149 ../../protocols/tcp.rst:452
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — This retransmission strategy has been refined based on the experience of using TCP on the Internet. The first refinement was a clarification of the strategy used to send acknowledgments. As TCP uses piggybacking, the easiest and less costly method to send acknowledgments is to place them in the data segments sent in the other direction. However, few application layer protocols exchange data in both directions at the same time and thus this method rarely works. For an application that is sending data segments in one direction only, the remote TCP entity returns empty TCP segments whose only useful information is their acknowledgment number. This may cause a large overhead in wide area network if a pure `ACK` segment is sent in response to each received data segment. Most TCP implementations use a `delayed acknowledgment` strategy. This strategy ensures that piggybacking is used whenever possible, otherwise pure `ACK` segments are sent for every second received data segments when there are no losses. When there are losses or reordering, `ACK` segments are more important for the sender and they are sent immediately :rfc:`813` :rfc:`1122`. This strategy relies on a new timer with a short delay (e.g. 50 milliseconds) and one additional flag in the TCB. It can be implemented as follows. 1301/10000 · 1301
149 ../../bibliography.rst:362
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Wessels, D., Fomenkov, M., `Wow, That's a lot of packets <https://www.caida.org/publications/papers/2003/dnspackets/>`_, Passive and Active Network Measurement Workshop (PAM), Apr 2003 185/10000 · 185
149 ../../principles/reliability.rst:508
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Checksums, CRCs,... 19/10000 · 19
150 ../../bibliography.rst:363
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Williams, R. `A painless guide to CRC error detection algorithms`, August 1993, unpublished manuscript, https://web.archive.org/web/20060101004751/http://www.ross.net/crc/download/crc_v3.txt 190/10000 · 190
150 ../../glossary.rst:171
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — router 6/10000 · 6