Exit Zen
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../../protocols/ipv6.rst:376
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The IPv6 `Hop-by-Hop Options` header
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../../protocols/ethernet.rst:364
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The `Spanning Tree Protocol` uses the ordering relationship to build the spanning tree. Each switch listens to `BPDUs` on its ports. When `BPDU = <R,c,T,p>` is received on port `q`, the switch computes the port's `root priority vector`: `V[q] = <R,c+cost[q],T,p,q>` , where `cost[q]` is the cost associated to the port over which the `BPDU` was received. The switch stores in a table the last `root priority vector` received on each port. The switch then compares its own `identifier` with the smallest `root identifier` stored in this table. If its own `identifier` is smaller, then the switch is the root of the spanning tree and is, by definition, at a distance `0` of the root. The `BPDU` of the switch is then `<R,0,R,p>`, where `R` is the switch `identifier` and `p` will be set to the port number over which the `BPDU` is sent.
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../../protocols/tcp.rst:315
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`Recent measurements <http://www.caida.org/research/traffic-analysis/pkt_size_distribution/graphs.xml>`_ indicate that these packet size distributions are still valid in today's Internet, although the packet distribution tends to become bi-modal with small packets corresponding to TCP pure acknowledgments and large 1440-bytes packets carrying most of the user data [SMASU2012]_.
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../../glossary.rst:32
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Metropolitan Area Network
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../../principles/network.rst:427
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Two virtual circuits pass through `R3`. They both need to be forwarded to `R4`, but `R4` expects `label=1` for packets belonging to the virtual circuit originated by `R2` and `label=0` for packets belonging to the other virtual circuit. `R3` could choose to leave the labels unchanged.
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../../principles/reliability.rst:393
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Frames can be corrupted by transmission errors
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../../principles/transport.rst:575
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Connection establishment
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../../principles/sharing.rst:479
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If two hosts are competing, the algorithm above will avoid a second collision 50% of the time. However, if the network is heavily loaded, several hosts may be competing at the same time. In this case, the hosts should be able to automatically adapt their retransmission delay. The `binary exponential back-off` performs this adaptation based on the number of collisions that have affected a frame. After the first collision, the host flips a coin and waits 0 or 1 `slot time`. After the second collision, it generates a random number and waits 0, 1, 2 or 3 `slot times`, etc. The duration of the waiting time is doubled after each collision. The complete pseudo-code for the CSMA/CD algorithm is shown in the figure below.
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../../principles/security.rst:1016
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The wikipedia page on passwords provides many of these references : https://en.wikipedia.org/wiki/Password_strength
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../../protocols/bgp.rst:410
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The bad gadget internetwork
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../../protocols/email.rst:246
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../../protocols/ethernet.rst:391
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Assume that `Switch4` is the first to boot. It sends its own `BPDU = <4,0,4,1>` (resp. `BPDU = <4,0,4,2>`) on port 1 (resp. port 2). When `Switch1` boots, it sends `BPDU = <1,0,1,1>`. This `BPDU` is received by `Switch4`, which updates its `BPDU` and root priority vector tables and computes a new `BPDU = <1,3,4,1>` (resp. `BPDU = <1,3,4,2>`) on port 1 (resp. port 2). Indeed, there is only one root priority vector and hence, it is the best one. Port 1 of `Switch4` becomes the `Root` port while its second port is still in the `Designated` state.
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../../protocols/ipv6.rst:378
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In this optional header, the `Next Header` field is used to support the chain of headers. It indicates the type of the next header in the chain. IPv6 headers have different lengths. The `Hdr Ext Len` field indicates the total length of the option header in bytes. The `Opt. Type` field indicates the type of option. These types are encoded such that their high order bits specify how the header needs to be handled by nodes that do not recognize it. The following values are defined for the two high order bits :
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../../protocols/ethernet.rst:366
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Otherwise, the switch chooses the best priority vector from its table, `bv = <R,c+cost[q'],T,p,q'>`. The port `q'`, over which this best root priority vector was learned, is the switch port that is closest to the `root` switch. This port becomes the `Root` port of the switch. There is only one `Root` port per switch (except for the `Root` switches whose ports are all `Designated`). The switch can then compute its own `BPDU` as `BPDU = <R,c',S,p>` , where `R` is the `root identifier`, `c'` the cost of the best root priority vector, `S` the identifier of the switch and `p` will be replaced by the number of the port over which the `BPDU` will be sent.
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../../protocols/tcp.rst:322
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TCP windows
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../../glossary.rst:253
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MIME
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../../principles/network.rst:432 • ../../principles/network.rst:434
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->R4
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../../principles/reliability.rst:394
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Frames can be lost or unexpected frames can appear
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../../principles/sharing.rst:504
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The inter-frame delay used in this pseudo-code is a short delay corresponding to the time required by a network adapter to switch from transmit to receive mode. It is also used to prevent a host from sending a continuous stream of frames without leaving any transmission opportunities for other hosts on the network. This contributes to the fairness of CSMA/CD. Despite this delay, there are still conditions where CSMA/CD is not completely fair [RY1994]_. Consider for example a network with two hosts : a server sending long frames and a client sending acknowledgments. Measurements reported in [RY1994]_ have shown that there are situations where the client could suffer from repeated collisions that lead it to wait for long periods of time due to the exponential back-off algorithm.
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../../principles/security.rst:1019
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A detailed explanation of the operation of the RSA algorithm is outside the scope of this e-book. Various tutorials such as the `RSA page <https://en.wikipedia.org/wiki/RSA_(cryptosystem)>`_ on wikipedia provide examples and tutorial information.
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