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162 ../../protocols/wifi.rst:29
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — When developing its family of standards, the `IEEE 802.11 working group <http://www.ieee802.org/11/>`_ took a similar approach as the `IEEE 802.3 working group <http://www.ieee802.org/3/>`_ that developed various types of physical layers for Ethernet networks. 802.11 networks use the CSMA/CA Medium Access Control technique described earlier and they all assume the same architecture and use the same frame format. 415/10000 · 415
162 ../../protocols/tcp.rst:533
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — To deal with the limited size of the SACK option, a TCP receiver currently having more than 3 blocks inside its receiving buffer must select the blocks to place in the SACK option. A good heuristic is to put in the SACK option the blocks that have most recently changed, as the sender is likely to be already aware of the older blocks. 335/10000 · 335
163 ../../glossary.rst:119
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A low-level API originally defined on Berkeley Unix to allow programmers to develop clients and servers. 104/10000 · 104
163 ../../principles/reliability.rst:804
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Go-back-n and selective repeat 30/10000 · 30
163 ../../principles/dv.rst:419
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Routers usually maintain at least two data structures that contain information about the reachable destinations. The first data structure is the `routing table`. The `routing table` is a data structure that associates a destination to an outgoing interface or a nexthop router and a set of additional attributes. Different routing protocols can associate different attributes for each destination. Distance vector routing protocols will store the cost to reach the destination along the shortest path. Other routing protocols may store information about the number of hops of the best path, its lifetime or the number of sub paths. A `routing table` may store different paths towards a given destination and flag one of them as the best one. 741/10000 · 741
163 ../../principles/sharing.rst:973
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — :math:`rate(t+1)=\alpha_N + \beta_N rate(t)` when the network is *not* congested 80/10000 · 80
163 ../../protocols/email.rst:264
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — 16 2/10000 · 2
163 ../../protocols/ipv6.rst:538
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — ``2`` : Beyond scope of source address. This message can be sent if the source is using link-local addresses to reach a global unicast address outside its subnet. 162/10000 · 162
163 ../../protocols/wifi.rst:35
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The architecture of WiFi networks is slightly different from the Local Area Networks that we have discussed until now. There are, in practice, two main types of WiFi networks : `independent` or `adhoc` networks and `infrastructure` networks [#fBSS]_. An `independent` or `adhoc` network is composed of a set of devices that communicate with each other. These devices play the same role and the `adhoc` network is usually not connected to the global Internet. `Adhoc` networks are used when for example a few laptops need to exchange information or to connect a computer with a WiFi printer. 591/10000 · 591
163 ../../protocols/tcp.rst:535
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — When a sender receives a SACK option indicating a new block and thus a new possible segment loss, it usually does not retransmit the missing segments immediately. To deal with reordering, a TCP sender can use a heuristic similar to `fast retransmit` by retransmitting a gap only once it has received three SACK options indicating this gap. It should be noted that the SACK option does not supersede the `acknowledgment number` of the TCP header. A TCP sender can only remove data from its sending buffer once they have been acknowledged by TCP's cumulative acknowledgments. This design was chosen for two reasons. First, it allows the receiver to discard parts of its receiving buffer when it is running out of memory without loosing data. Second, as the SACK option is not transmitted reliably, the cumulative acknowledgments are still required to deal with losses of `ACK` segments carrying only SACK information. Thus, the SACK option only serves as a hint to allow the sender to optimize its retransmissions. 1012/10000 · 1012
164 ../../glossary.rst:105
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — spoofed packet 14/10000 · 14
164 ../../principles/dv.rst:421
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — The `routing table` is a software data structure which is updated by (one or more) routing protocols. The `routing table` is usually not directly used when forwarding packets. Packet forwarding relies on a more compact data structure which is the `forwarding table`. On high-end routers, the `forwarding table` is implemented directly in hardware while lower performance routers will use a software implementation. A `forwarding table` contains a subset of the information found in the `routing table`. It only contains the nexthops towards each destination that are used to forward packets and no attributes. A `forwarding table` will typically associate each destination to one or more outgoing interface or nexthop router. 725/10000 · 725
164 ../../principles/sharing.rst:975
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — With a linear adaption algorithm, :math:`\alpha_C,\alpha_N, \beta_C` and :math:`\beta_N` are constants. The analysis of [CJ1989]_ shows that to be fair and efficient, such a binary rate adaption mechanism must rely on `Additive Increase and Multiplicative Decrease`. When the network is not congested, the hosts should slowly increase their transmission rate (:math:`\beta_N=1~and~\alpha_N>0`). When the network is congested, the hosts must multiplicatively decrease their transmission rate (:math:`\beta_C < 1~and~\alpha_C = 0`). Such an AIMD rate adaptation algorithm can be implemented by the pseudo-code below. 614/10000 · 614
164 ../../protocols/email.rst:264
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Q 1/10000 · 1
164 ../../protocols/ipv6.rst:539
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — ``3`` : Address unreachable. This message indicates that the packet reached the subnet of the destination, but the host that owns this destination address cannot be reached. 173/10000 · 173
164 ../../protocols/wifi.rst:42
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — An 802.11 independent or adhoc network 38/10000 · 38
164 ../../protocols/tcp.rst:537
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — As explained earlier, the TCP Timestamp option :rfc:`1323` prevents ambiguities while collecting round-trip-time measurements. It plays another very important role in today's high-bandwidth networks. Since TCP uses 32 bits long sequence numbers, the sequence numbers wrap after the transmission of 4 GBytes of data. With 10 Gbps and soon 100 Gbps interfaces, TCP only needs to transmit during a few seconds before reusing the same sequence number. Given that the Maximum Segment Lifetime is still 2 minutes, several packets, belonging to the same TCP connection could use the same sequence number. If one of these packets is severely delayed through the network, it could reappear at the same time as a packet with the same TCP sequence number. To prevent this problem, most modern TCP implementations associate a TCP timestamp option to each segment on transmission. When a TCP stack receives a TCP segment, it checks that its TCP timestamp is valid and if not the segment is discarded :rfc:`7323`. 999/10000 · 999
164 ../../principles/reliability.rst:806
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — To overcome the performance limitations of the alternating bit protocol, reliable protocols rely on `pipelining`. This technique allows a sender to transmit several consecutive frames without being forced to wait for an acknowledgment after each frame. Each data frame contains a sequence number encoded as an `n` bits field. 325/10000 · 325
165 ../../glossary.rst:107
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — A packet is said to be spoofed when the sender of the packet has used as source address a different address than its own. 121/10000 · 121
165 ../../principles/reliability.rst:812
	English ↹ ↵ NBS … “ ” ‘ ’ ﹙-﹚ ‐ – — Pipelining improves the performance of reliable protocols 57/10000 · 57