Exit Zen
39
../../protocols/ipv6.rst:130
English
IPv6 supports unicast, multicast and anycast addresses. An IPv6 unicast address is used to identify one datalink-layer interface on a host. If a host has several datalink layer interfaces (e.g. an Ethernet interface and a WiFi interface), then it needs several IPv6 addresses. In general, an IPv6 unicast address is structured as shown in the figure below.
0/3560 · 356
39
../../protocols/ethernet.rst:162
English
In the late 1980s, 10 Mbps became too slow for some applications and network manufacturers developed several LAN technologies that offered higher bandwidth, such as the 100 Mbps FDDI LAN that used optical fibers. As the development of 10Base5, 10Base2 and 10BaseT had shown that Ethernet could be adapted to different physical layers, several manufacturers started to work on 100 Mbps Ethernet and convinced IEEE to standardize this new technology that was initially called `Fast Ethernet`. `Fast Ethernet` was designed under two constraints. First, `Fast Ethernet` had to support twisted pairs. Although it was easier from a physical layer perspective to support higher bandwidth on coaxial cables than on twisted pairs, coaxial cables were a nightmare from deployment and maintenance perspectives. Second, `Fast Ethernet` had to be perfectly compatible with the existing 10 Mbps Ethernet to allow `Fast Ethernet` technology to be used initially as a backbone technology to interconnect 10 Mbps Ethernet networks. This forced `Fast Ethernet` to use exactly the same frame format as 10 Mbps Ethernet. This implied that the minimum `Fast Ethernet` frame size remained at 512 bits. To preserve CSMA/CD with this minimum frame size and 100 Mbps instead of 10 Mbps, the duration of the `slot time` was decreased to 5.12 microseconds.
0/13290 · 1329
39
../../protocols/routing.rst:132
English
Each router must exchange HELLOs and link state packets with all the other routers on the LAN. This increases the number of OSPF packets that are sent and processed by each router.
0/1800 · 180
39
../../protocols/rpc.rst:138
English
The `id` field, which is present in the request and the response plays the same role as the identifier field in the DNS message. It allows the caller to match the response with the request that it sent. This `id` is very important when JSON-RPC is used over the connectionless transport service which is unreliable. If a request is sent, it may need to be retransmitted and it is possible that a callee will receive twice the same request (e.g. if the response for the first request was lost). In the DNS, when a request is lost, it can be retransmitted without causing any difficulty. However with remote procedure calls in general, losses can cause some problems. Consider a method which is used to deposit money on a bank account. If the request is lost, it will be retransmitted and the deposit will be eventually performed. However, if the response is lost, the caller will also retransmit its request. This request will be received by the callee that will deposit the money again. To prevent this problem from affecting the application, either the programmer must ensure that the remote procedures that it calls can be safely called multiple times or the application must verify whether the request has been transmitted earlier. In most deployments, the programmers use remote methods that can be safely called multiple times without breaking the application logic.
0/13710 · 1371
39
../../protocols/ssh.rst:296
English
For some of the algorithms, it is possible to negotiate the utilization of no algorithm. This happens frequently for the compression algorithm that is not always used. For this, both the client and the server must announce ``null`` in their ordered list of supported algorithms.
0/2780 · 278
39
../../protocols/tcp.rst:121
English
the `acknowledgment number` set to the `sequence number` of the received `SYN` segment incremented by 1 :math:`\pmod{2^{32}}`. When a TCP entity sends a segment having `x+1` as acknowledgment number, this indicates that it has received all data up to and including sequence number `x` and that it is expecting data having sequence number `x+1`. As the `SYN` flag was set in a segment having sequence number `x`, this implies that setting the `SYN` flag in a segment consumes one sequence number.
0/4950 · 495
39
../../protocols/tls.rst:167
English
`Extensions` : TLS supports various extensions in the ``ClientHello`` message. These extensions :rfc:`6066` are important to allow the protocol to evolve, but many of them go beyond the scope of this chapter.
0/2080 · 208
39
../../protocols/wifi.rst:99
English
802.11 data frame format
0/240 · 24
40
../../bibliography.rst:126
English
McQuillan, J. M., Richer, I., and Rosen, E. C., `An overview of the new routing algorithm for the ARPANET <http://doi.acm.org/10.1145/800092.802981>`_. In Proceedings of the Sixth Symposium on Data Communications (Pacific Grove, California, United States, November 27 - 29, 1979). SIGCOMM '79. ACM, New York, NY, 63-68.
0/3190 · 319
40
../../glossary.rst:325
English
Ethernet
0/100 · 8
40
../../exercises/ex-sharing.rst:647
English
the host continues to listen until the communication channel becomes free. It transmits as soon as the communication channel becomes free.
0/1380 · 138
40
../../principles/sharing.rst:179
English
Discarding packets is one of the signals that the network nodes can use to inform the hosts of the current level of congestion. Buffers on network nodes are usually used as FIFO queues to preserve packet ordering. Several `packet discard mechanisms` have been proposed for network nodes. These techniques basically answer two different questions :
0/3470 · 347
40
../../principles/security.rst:398
English
The Elliptic Curve Cryptography techniques [#fecc]_ that rely on special properties of elliptic curves.
0/1030 · 103
40
../../exercises/ipv6.rst:416
English
on router ``R6``
0/160 · 16
40
../../exercises/routing-protocols.rst:491
English
The last step is to specify to which AS each router belongs and to configure the eBGP sessions and their routing policies. IPMininet_ abstracts most of the complexity of the configuration of these policies by supporting two policies
0/2320 · 232
40
../../exercises/tcp-2.rst:502
English
We can now explore how TCP's retransmission techniques interact with the congestion control scheme. The Linux TCP code that combines these two techniques contains several heuristics to improve their performance. We start with a transfer of 8KBytes where the penultimate segment is not received by the remote host. In this case, TCP does not receive enough acknowledgments to trigger the fast retransmit and it must wait for the expiration of the retransmission timer. This script is available from :download:`/exercises/packetdrill_scripts/slow-start-rto2.pkt`.
0/5610 · 561
40
../../protocols/bgp.rst:127
English
`KEEPALIVE` : this message is used to ensure a regular exchange of messages on the BGP session, even when no route changes. When a BGP router has not sent an `UPDATE` message during the last 30 seconds, it shall send a `KEEPALIVE` message to confirm to the other peer that it is still up. If a peer does not receive any BGP message during a period of 90 seconds [#fdefaultkeepalive]_, the BGP session is considered to be down and all the routes learned over this session are withdrawn.
0/4850 · 485
40
../../protocols/congestion.rst:205
English
:math:`Throughput=\frac{area \times MSS}{time} = \frac{ \frac{3 \times W^2}{8}}{\frac{W}{2} \times rtt}` or, after having eliminated `W`, :math:`Throughput=\sqrt{\frac{3}{2}} \times \frac{MSS}{rtt \times \sqrt{p}}`
0/2140 · 214
40
../../protocols/email.rst:212
English
`text`. The message part contains information in textual format. There are several subtypes : `text/plain` for regular ASCII text, `text/html` defined in :rfc:`2854` for documents in :term:`HTML` format or the `text/enriched` format defined in :rfc:`1896`. The `Content-Type:` header line may contain a second parameter that specifies the character set used to encode the text. `charset=us-ascii` is the standard ASCII character table. Other frequent character sets include `charset=UTF8` or `charset=iso-8859-1`. The `list of standard character sets <http://www.iana.org/assignments/character-sets>`_ is maintained by :term:`IANA`.
0/6330 · 633
40
../../protocols/ethernet.rst:177
English
1000Base-CX
0/110 · 11