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../../glossary.rst:167
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A Network Address Translator is a middlebox that translates IP packets.
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../../principles/dv.rst:14
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`R[d].cost` is the sum of the metrics of the links that compose the shortest path to reach destination `d`
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../../principles/transport.rst:672
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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`.
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../../principles/sharing.rst:603
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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.
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../../protocols/bgp.rst:436
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The first guideline implies that the provider of the provider of `ASx` cannot be a customer of `ASx`. Such a relationship would not make sense from an economic perspective as it would imply circular payments. Furthermore, providers are usually larger than customers.
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../../protocols/email.rst:252
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K
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../../protocols/ipv6.rst:406
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9180 bytes
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../../protocols/ethernet.rst:395
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During the computation of the spanning tree, switches discard all received data frames, as at that time the network topology is not guaranteed to be loop-free. Once that topology has been stable for some time, the switches again start to use the MAC learning algorithm to forward data frames. Only the `Root` and `Designated` ports are used to forward data frames. Switches discard all the data frames received on their `Blocked` ports and never forward frames on these ports.
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../../protocols/tcp.rst:349
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86 Gbps
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../../glossary.rst:310
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NBMA
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../../principles/dv.rst:15
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`R[d].time` is the timestamp of the last distance vector containing destination `d`
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../../principles/transport.rst:674
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The three way handshake is illustrated in the figure below.
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../../principles/sharing.rst:609
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Reservations with CSMA/CA
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../../protocols/bgp.rst:438
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The second guideline also corresponds to economic preferences. Since a provider earns money when sending packets to one of its customers, it makes sense to prefer such customer learned routes over routes learned from providers. [GR2001]_ also shows that BGP convergence is guaranteed even if an AS associates the same preference to routes learned from a `shared-cost` peer and routes learned from a customer.
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../../protocols/email.rst:252
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../../protocols/ipv6.rst:407
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802.15.4
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../../protocols/ethernet.rst:397
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Switches, ports and links can fail in a switched Ethernet network. When a failure occurs, the switches must be able to recompute the spanning tree to recover from the failure. The `Spanning Tree Protocol` relies on regular transmissions of the `BPDUs` to detect these failures. A `BPDU` contains two additional fields : the `Age` of the `BPDU` and the `Maximum Age`. The `Age` contains the amount of time that has passed since the root switch initially originated the `BPDU`. The root switch sends its `BPDU` with an `Age` of zero and each switch that computes its own `BPDU` increments its `Age` by one. The `Age` of the `BPDUs` stored on a switch's table is also incremented every second. A `BPDU` expires when its `Age` reaches the `Maximum Age`. When the network is stable, this does not happen as `BPDU` s are regularly sent by the `root` switch and downstream switches. However, if the `root` fails or the network becomes partitioned, `BPDU` will expire and switches will recompute their own `BPDU` and restart the `Spanning Tree Protocol`. Once a topology change has been detected, the forwarding of the data frames stops as the topology is not guaranteed to be loop-free. Additional details about the reaction to failures may be found in [IEEE802.1d]_.
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../../protocols/tcp.rst:350
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17 Gbps
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../../glossary.rst:312
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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.
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../../principles/dv.rst:17
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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.
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