Exit Zen
122
../../principles/dv.rst:13
English
`R[d].link` is the outgoing link that the router uses to forward packets towards destination `d`
0/960 · 96
122
../../principles/reliability.rst:419
English
For example, consider a sender that sends `111`. If there is one bit in error, the receiver could receive `011` or `101` or `110`. In these three cases, the receiver will decode the received bit pattern as a `1` since it contains a majority of bits set to `1`. If there are two bits in error, the receiver will not be able anymore to recover from the transmission error.
0/3700 · 370
122
../../principles/sharing.rst:597
English
The hidden station problem
0/260 · 26
122
../../principles/transport.rst:670
English
The initiating entity receives the `CA` segment. The acknowledgment number of this segment confirms that the remote entity has correctly received the `CR` segment. The transport connection is considered to be established by the initiating entity and the numbering of the data segments starts at sequence number `x`. Before sending data segments, the initiating entity must acknowledge the received `CA` segments by sending another `CA` segment.
0/4440 · 444
123
../../glossary.rst:167
English
A Network Address Translator is a middlebox that translates IP packets.
0/710 · 71
123
../../principles/dv.rst:14
English
`R[d].cost` is the sum of the metrics of the links that compose the shortest path to reach destination `d`
0/1060 · 106
123
../../principles/sharing.rst:603
English
To avoid collisions in these situations, CSMA/CA allows devices to reserve the transmission channel for some time. This is done by using two control frames : `Request To Send` (RTS) and `Clear To Send` (CTS). Both are very short frames to minimize the risk of collisions. To reserve the transmission channel, a device sends a RTS frame to the intended recipient of the data frame. The RTS frame contains the duration of the requested reservation. The recipient replies, after a SIFS delay, with a CTS frame which also contains the duration of the reservation. As the duration of the reservation has been sent in both RTS and CTS, all hosts that could collide with either the sender or the reception of the data frame are informed of the reservation. They can compute the total duration of the transmission and defer their access to the transmission channel until then. This is illustrated in the figure below where host `A` reserves the transmission channel to send a data frame to host `B`. Host `C` notices the reservation and defers its transmission.
0/10530 · 1053
123
../../principles/transport.rst:672
English
The remote entity considers the transport connection to be established after having received the segment that acknowledges its `CA` segment. The numbering of the data segments sent by the remote entity starts at sequence number `y`.
0/2320 · 232
124
../../glossary.rst:310
English
NBMA
0/100 · 4
124
../../principles/dv.rst:15
English
`R[d].time` is the timestamp of the last distance vector containing destination `d`
0/830 · 83
124
../../principles/sharing.rst:609
English
Reservations with CSMA/CA
0/250 · 25
124
../../principles/transport.rst:674
English
The three way handshake is illustrated in the figure below.
0/590 · 59
125
../../glossary.rst:312
English
A Non Broadcast Mode Multiple Access Network is a subnetwork that supports multiple hosts/routers but does not provide an efficient way of sending broadcast frames to all devices attached to the subnetwork. ATM subnetworks are an example of NBMA networks.
0/2550 · 255
125
../../principles/dv.rst:17
English
A router that uses distance vector routing regularly sends its distance vector over all its interfaces. This distance vector is a summary of the router's routing table that indicates the distance towards each known destination. This distance vector can be computed from the routing table by using the pseudo-code below.
0/3190 · 319
125
../../principles/reliability.rst:426
English
To understand `error detection codes`, let us consider two devices that exchange bit strings containing `N` bits. To allow the receiver to detect a transmission error, the sender converts each string of `N` bits into a string of `N+r` bits. Usually, the `r` redundant bits are added at the beginning or the end of the transmitted bit string, but some techniques interleave redundant bits with the original bits. An `error detection code` can be defined as a function that computes the `r` redundant bits corresponding to each string of `N` bits. The simplest error detection code is the parity bit. There are two types of parity schemes : even and odd parity. With the `even` (resp. `odd`) parity scheme, the redundant bit is chosen so that an even (resp. odd) number of bits are set to `1` in the transmitted bit string of `N+r` bits. The receiver can easily recompute the parity of each received bit string and discard the strings with an invalid parity. The parity scheme is often used when 7-bit characters are exchanged. In this case, the eighth bit is often a parity bit. The table below shows the parity bits that are computed for bit strings containing three bits.
0/11720 · 1172
125
../../principles/sharing.rst:611
English
The utilization of the reservations with CSMA/CA is an optimization that is useful when collisions are frequent. If there are few collisions, the time required to transmit the RTS and CTS frames can become significant and in particular when short frames are exchanged. Some devices only turn on RTS/CTS after transmission errors.
0/3290 · 329
125
../../principles/transport.rst:680
English
Three-way handshake
0/190 · 19
126
../../glossary.rst:298
English
network-byte order
0/180 · 18
126
../../principles/dv.rst:31
English
When a router boots, it does not know any destination in the network and its routing table only contains its local address(es). It thus sends to all its neighbors a distance vector that contains only its address at a distance of `0`. When a router receives a distance vector on link `l`, it processes it as follows.
0/3150 · 315
126
../../principles/reliability.rst:429
English
3 bits string
0/130 · 13