DHCP is listed as level 2. Shoudn't it be on a higher level. For instance level 7? 212.251.156.205 ( talk) 20:39, 7 May 2011 (UTC)
Hi there people,
I see the E1 and SONET/SDH are placed as layer 1 in the OSI model frame. My doubt is that E1 and SONET/SDH also treat the information at the logical level,for example, when processing CRC checks, analysing the time slot 16 (E1 PCM30) and many more in the case of the SONET/SDH. So, in my oppinion, these standards should have a secondary specification, as for example E1 PHY, or SONET PHY, to clarify about which part of the standard we are talking about. The CRC-4 feature, for example, is a feature related as layer 2. As stated in the artcicle "The Data Link Layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical Layer." This is an example of the physical and logical characteristics of these standards (E1 and SONET/SDH).
Cheers!
Carlos Jazbinsek ( talk) 15:37, 8 February 2010 (UTC)
The CRC4 is a layer 1 feature. CRC4 doesn't transfer data between network entities; CRC4 appeared in order to avoid FAS simulation on PCM streams and improve quality supervision on the receiver end (no error correction, only detection). Data in time slot 16 is CRC16 checked. User's Access to ISDN layer 2 protocol (Q.921) use CRC16 error detection to ask retransmission (and thus "correct" error). Cardeña. — Preceding unsigned comment added by 2.137.21.214 ( talk) 18:45, 22 November 2011 (UTC)
Dear all,
there is a huge misunderstanding of what the OSI model is. The article on the OSI actually represents this very clearly. Note that the OSI model is a structure that applies (fully or in parts) for any digital communication network. Fitting candidates are ISDN, SDH, ATM, Ethernet, RPR, IP, and so on.
IP lacks its own lower layers and therefore must use the network layer of some other network scheme to have transfer functions that are capable to get an IP packet from one router to the next. Commonly this is today Ethernet, but other were used and are still used as well (ISDN, SDH, ATM). For a clear view all protocols that are capable to provide an end-to-end connection passing some intermediate node (e.g. a cross-connect, a switch, a router, or something similar) should be placed at OSI Layer 3.
The OSI IP model defines a hierarchy of these network layers, and that is accidentally also refereed to as the OSI model, causing a lot of misunderstanding and confusion.
Therefore any figure showing other network protocol's acronyms never refers to the technology independent OSI model defined in ITU-T X.200.
85.127.103.152 ( talk) 12:08, 24 May 2010 (UTC) by Sprawl.
Some articles have put it at the top of the page. Others put it after the lead. I assume consistency is good. What's the best place? -- Kvng ( talk) 16:53, 4 July 2010 (UTC)
There are huge misunderstandings in this graphic of what Layer 5 to 7 protocols are. The graphic shows protocols such as HTTP and SNMP at layer 7 when they are clearly layer 5 protocols. The corresponding layer 6 for these are HTML/XML for HTTP, and MIB (via OID's) for SNMP. The layer 7 is then your web browser or MIB browser. SIP is shown at layer 5 and 7 while it is clearly a layer 5 protocol. Some of the others like FTP and Telnet don't fit into this definition as they combine layers 5-7.
I agree with the previous poster, any figure showing any network protocol acronyms never refers to the technology independent OSI model defined in ITU-T X.200. —Preceding unsigned comment added by 174.26.249.198 ( talk) 04:54, 25 July 2010 (UTC)
Someone should fix the link to Blue or remove it.
According to its wikipedia entry, SPDY is application-level ( http://en.wikipedia.org/wiki/SPDY ). Why is it at level 5? — Preceding unsigned comment added by 173.206.240.25 ( talk) 22:38, 30 July 2011 (UTC)
PPTP belongs to the "data link layer". You can find in this table OSI_model#Examples and in lots of places in internet. If nobody will object it, I will move PPTP to the data link layer in 7 days.-- Sena ( talk) 08:33, 15 September 2011 (UTC)
(Copied here from Talk:OSI_model#Two_devices_in_protocol_sidebar.)
In the sidebar, "hub" is listed as Layer 1. While a hub is a device that operates at Layer 1, I don't believe physical devices should be listed on the table. Likewise for Network Switch listed on Layer 2.
If devices are going to be listed, where does it end, pots is listed, should we then list all the devices that pots plugs into(DMS, 5E, Telica, PBX, etc...) I don't think that's the route the article should go, let the Ethernet Hub, Ethernet Switch pages describe there functionality in reguards to the Protocol(s) they run, IE 802.2/802.3/Ethernet II, etc....
— Preceding unsigned comment added by KMurphy111 ( talk • contribs) 15:26, July 12, 2012
Should we even be mentioning X.25 here? It spans layers 1, 2 and 3 and, according to the the X.25 article, is data-linked w/ LAPB. AngusCA ( talk) 16:50, 20 June 2013 (UTC)
In the industry, X.25 is differentiated even though there is only one spec: X.25 LAPB is the layer 2 part, X.25 PLP (Packet Layer Protocol) is the layer 3 part. LAPD, LAPF, and several other LAP protocols are very similar to LAPB (LAPD and LAPF are subsets of LAPB). LAPD is defined in Q.921 and LAPF is Q.922. IIRC X.25 doesn't specify a physical layer (but I've only seen it on HDLC) — Preceding unsigned comment added by Hank1230071224 ( talk • contribs) 10:39, August 5, 2013
I am puzzled by the way the various protocols have been classified in these pages. My understanding is as follows.
The OSI Physical Layer = the definition of the physical infrastructure capable of providing an (unreliable) symbol stream between two directly connected endpoints. The symbols are often bits, but can be from any finite alphabet. The key characteristics of the physical layer are (a) that it is between two directly connected endpoints (there is no concept of network address), and it is unreliable. Examples: RS-232, RS-422, 10Base5, 10BaseT, 100BaseTX, V.22, etc. Copper cable, optical cable, wireless carrier signal, smoke signals, etc.
The OSI Link Layer = the layer which turns an unreliable symbol stream connection between two directly connected endpoints into a reliable symbol stream connection between two directly connected endpoints. The key characteristics of the link layer are (a) that it is between two directly connected endpoints (there is no concept of a network address), and it is reliable. Examples: v.41, v.42, v.42bis. PPP, Zmodem, Kermit. Error-correcting code / error-detecting code with retransmission protocol, superimposed on a raw binary channel.
The OSI Network Layer = the layer which turns reliable direct connections between pairs of directly connected endpoints into a network, i.e. a communications medium in which each endpoint can send a packet to another endpoint by relaying its packet to its (directly connected) gateway and providing to the gateway a delivery address on the network. The sender does not have to worry further about the message getting delivered — the network layer provides the necessary routing to deliver the message. Message delivery is not necessarily reliable (delivery is not guaranteed and the sender does not know if it has been delivered). The key characteristics of the network layer are (a) that it is between a sender and an addressee (there is a concept of a network address), and that it is unreliable.
The OSI Transport Layer = the layer which turns an unreliable channel for sending addressed packets into a reliable channel for sending addressed packets. The key characteristics of the transport layer are (a) that it is between a sender and an addressee (there is a concept of a network address), and that it is reliable.
The Internet (IP) and the Ethernet layer are both OSI Network layer protocols, where the IP network layer is layered on top of the Ethernet network layer. The Ethernet layer is not a data link layer.
There is nothing unusual about stacking OSI Layers in a way which doesn't build OSI Layer (n+1) on top of OSI Layer n. PPPoE is an OSI Link Layer (PPP) stacked on top of an OSI Network Layer (Ethernet). ZModem run on a serial line provided by a modem which already provides v.42bis error correction is an OSI Link Layer stacked on top of another OSI Link Layer. ZModem run over ssh is OSI Link Layer run on top of an OSI Application Layer.
To distinguish between the two network layers, the early pioneers of the Internet (who were familiar with the OSI Model) referred to the network layer(s) on top of which the IP protocol operated the network layer, or the network connection layer, and to the new network layer which they were creating, which was connecting existing networks (and network layer protocols) into a bigger network (and more universal network protocol) the inter-network layer.
It is also not the case, as is claimed on many pages in this series that there is no correspondence between the OSI layers and the TCP/IP layers. The layers are clearly defined, and the correspondence is there and it is very clear.
E.g. IP is an OSI Network Layer protocol implemented on top of other OSI Network Layer protocols, such as, e.g. the MAC/Ethernet layer.
I have re-arranged some of the protocols in line with the above definitions, though I think several of them are still in the wrong place.
Tarian.liber ( talk) 01:00, 29 August 2013 (UTC)
Tarian.liber ( talk) 22:21, 3 September 2013 (UTC)
It is difficult to have a discussion if you ignore counter-arguments. I have made several attempts to explain the Wikiquette but you keep violating it. When you get into a discussion like this you cannot expect others to wait half a week for your reply. Ad hominem attacks do not help your position.
Even university libraries don't carry Beauchamp. Unfortunately you won't answer clarifying questions about what he really says either. The two references I gave, in contrast, are reliable beyond doubt and readily available. You're also wrong about history: the OSI reference model does not predate TCP/IP. But this is irrelevant to the discussion. And again, error detection is not reliability.
Your main argument appears to be that there are no addresses at the data-link layer. Here's what the actual OSI standard has to say (ISO/IEC 7498-1, p.46):
"7.6.3.2 In connection-less mode, the facilities provided by the Data Link Layer are:
a) data-link-addresses"
It says nothing about "directly connected". What other argument did I miss? -- EnOreg ( talk) 08:59, 4 September 2013 (UTC)
Tarian, there are two issues here. The first is that this is a template talk page, and that's not where content is being discussed, and not where content decisions are being made. The template collects what the article describes. I don't agree with many of the placements of protocols on particular OSI or TCP/IP layers, but this is not the place to discuss that, and this is not the place to get consensus on content changes.
The second issue is that there are thousands of books about it, and that quite a few of them don't get it quite right. If the definition of the first four layers is in Beauchamp as you quoted it here then this book belongs to that large group; there is almost nothing right in those four layer characterisations, not even the layer names (There's no Transmission Layer). Yes, books are reliable sources but there is no problem providing other books that don't put it that way, as has happened in the article on the OSI model, for instance. Hope this helps, Pgallert ( talk) 11:53, 4 September 2013 (UTC)
And can we get back to the original issue being discussed. So far the quotes do not explicitly say that IEEE 802.3 protocols are in the network layer. In fact, from sources I see that the OSI model was developed from 1977 to 1979 (totally missing from that article, sigh) while 802.3 did not come out until 1983 (although Ethernet of course was done before OSI), so all three (OSI, IEEE and IP protocol suite) were essentially going on in parallel. As a compromise, I would say it might be safe to say that the IEEE (and IP to a lesser extent) protocols do not fit directly into the OSI model, so they should be removed from this template. In fact, the template is not transcluded in the IEEE 802.3 nor IEEE 802.2 articles, which is another good idea to remove them from this template. And eventually we do need to discuss the edits to the OSI model article too which are a bit misleading. For example, the OSI model (or at least the ISO protocol stack that resulted) had both connection-oriented and connectionless network layers. In connection-oriented networks, virtual circuits were the abstraction, not datagrams, which were associated with connectionless networks only. Many (not all certainly) were from the phone companies after all. W Nowicki ( talk) 16:09, 4 September 2013 (UTC)
Sorry, I'm getting a bit forgetful these days and I forgot what my own point about the timeline was, and now I remembered. To those who claim that Ethernet does not define a layer which belongs to OSI Layer 3 (and that the relative timeline of coming into being of OSI and the Internet does not matter), I ask this question: before the Internet came along, which stitched together all the other networks, and introduced an 'inter'-networking network layer on top of the network layer of other networks, and before TCP/IP became standardized, people were already using Ethernet for their networking. So which part of their (our) networking stack formed OSI Layer 3 in those days then? Just answer this question for me, please.
Tarian.liber ( talk) 02:03, 6 September 2013 (UTC)
I see that TLS/SSL is shown in this template as a layer 5 protocol. I think this is misleading. TLS/SSL do not operate at layer 5. In the Transport_Layer_Security article there is a paragraph stating that TLS is initiated at layer 5 and operates at layer 6 and there is an infobox statig that TLS operates at layer 7 - so we are not being consistent. I think the reality is that TLS does not really fall nicely into any layer of the model and I would suggest its clearer to just remove it from this template altogether. Nicholsr ( talk) 17:44, 3 January 2014 (UTC)
DHCP is listed as level 2. Shoudn't it be on a higher level. For instance level 7? 212.251.156.205 ( talk) 20:39, 7 May 2011 (UTC)
Hi there people,
I see the E1 and SONET/SDH are placed as layer 1 in the OSI model frame. My doubt is that E1 and SONET/SDH also treat the information at the logical level,for example, when processing CRC checks, analysing the time slot 16 (E1 PCM30) and many more in the case of the SONET/SDH. So, in my oppinion, these standards should have a secondary specification, as for example E1 PHY, or SONET PHY, to clarify about which part of the standard we are talking about. The CRC-4 feature, for example, is a feature related as layer 2. As stated in the artcicle "The Data Link Layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical Layer." This is an example of the physical and logical characteristics of these standards (E1 and SONET/SDH).
Cheers!
Carlos Jazbinsek ( talk) 15:37, 8 February 2010 (UTC)
The CRC4 is a layer 1 feature. CRC4 doesn't transfer data between network entities; CRC4 appeared in order to avoid FAS simulation on PCM streams and improve quality supervision on the receiver end (no error correction, only detection). Data in time slot 16 is CRC16 checked. User's Access to ISDN layer 2 protocol (Q.921) use CRC16 error detection to ask retransmission (and thus "correct" error). Cardeña. — Preceding unsigned comment added by 2.137.21.214 ( talk) 18:45, 22 November 2011 (UTC)
Dear all,
there is a huge misunderstanding of what the OSI model is. The article on the OSI actually represents this very clearly. Note that the OSI model is a structure that applies (fully or in parts) for any digital communication network. Fitting candidates are ISDN, SDH, ATM, Ethernet, RPR, IP, and so on.
IP lacks its own lower layers and therefore must use the network layer of some other network scheme to have transfer functions that are capable to get an IP packet from one router to the next. Commonly this is today Ethernet, but other were used and are still used as well (ISDN, SDH, ATM). For a clear view all protocols that are capable to provide an end-to-end connection passing some intermediate node (e.g. a cross-connect, a switch, a router, or something similar) should be placed at OSI Layer 3.
The OSI IP model defines a hierarchy of these network layers, and that is accidentally also refereed to as the OSI model, causing a lot of misunderstanding and confusion.
Therefore any figure showing other network protocol's acronyms never refers to the technology independent OSI model defined in ITU-T X.200.
85.127.103.152 ( talk) 12:08, 24 May 2010 (UTC) by Sprawl.
Some articles have put it at the top of the page. Others put it after the lead. I assume consistency is good. What's the best place? -- Kvng ( talk) 16:53, 4 July 2010 (UTC)
There are huge misunderstandings in this graphic of what Layer 5 to 7 protocols are. The graphic shows protocols such as HTTP and SNMP at layer 7 when they are clearly layer 5 protocols. The corresponding layer 6 for these are HTML/XML for HTTP, and MIB (via OID's) for SNMP. The layer 7 is then your web browser or MIB browser. SIP is shown at layer 5 and 7 while it is clearly a layer 5 protocol. Some of the others like FTP and Telnet don't fit into this definition as they combine layers 5-7.
I agree with the previous poster, any figure showing any network protocol acronyms never refers to the technology independent OSI model defined in ITU-T X.200. —Preceding unsigned comment added by 174.26.249.198 ( talk) 04:54, 25 July 2010 (UTC)
Someone should fix the link to Blue or remove it.
According to its wikipedia entry, SPDY is application-level ( http://en.wikipedia.org/wiki/SPDY ). Why is it at level 5? — Preceding unsigned comment added by 173.206.240.25 ( talk) 22:38, 30 July 2011 (UTC)
PPTP belongs to the "data link layer". You can find in this table OSI_model#Examples and in lots of places in internet. If nobody will object it, I will move PPTP to the data link layer in 7 days.-- Sena ( talk) 08:33, 15 September 2011 (UTC)
(Copied here from Talk:OSI_model#Two_devices_in_protocol_sidebar.)
In the sidebar, "hub" is listed as Layer 1. While a hub is a device that operates at Layer 1, I don't believe physical devices should be listed on the table. Likewise for Network Switch listed on Layer 2.
If devices are going to be listed, where does it end, pots is listed, should we then list all the devices that pots plugs into(DMS, 5E, Telica, PBX, etc...) I don't think that's the route the article should go, let the Ethernet Hub, Ethernet Switch pages describe there functionality in reguards to the Protocol(s) they run, IE 802.2/802.3/Ethernet II, etc....
— Preceding unsigned comment added by KMurphy111 ( talk • contribs) 15:26, July 12, 2012
Should we even be mentioning X.25 here? It spans layers 1, 2 and 3 and, according to the the X.25 article, is data-linked w/ LAPB. AngusCA ( talk) 16:50, 20 June 2013 (UTC)
In the industry, X.25 is differentiated even though there is only one spec: X.25 LAPB is the layer 2 part, X.25 PLP (Packet Layer Protocol) is the layer 3 part. LAPD, LAPF, and several other LAP protocols are very similar to LAPB (LAPD and LAPF are subsets of LAPB). LAPD is defined in Q.921 and LAPF is Q.922. IIRC X.25 doesn't specify a physical layer (but I've only seen it on HDLC) — Preceding unsigned comment added by Hank1230071224 ( talk • contribs) 10:39, August 5, 2013
I am puzzled by the way the various protocols have been classified in these pages. My understanding is as follows.
The OSI Physical Layer = the definition of the physical infrastructure capable of providing an (unreliable) symbol stream between two directly connected endpoints. The symbols are often bits, but can be from any finite alphabet. The key characteristics of the physical layer are (a) that it is between two directly connected endpoints (there is no concept of network address), and it is unreliable. Examples: RS-232, RS-422, 10Base5, 10BaseT, 100BaseTX, V.22, etc. Copper cable, optical cable, wireless carrier signal, smoke signals, etc.
The OSI Link Layer = the layer which turns an unreliable symbol stream connection between two directly connected endpoints into a reliable symbol stream connection between two directly connected endpoints. The key characteristics of the link layer are (a) that it is between two directly connected endpoints (there is no concept of a network address), and it is reliable. Examples: v.41, v.42, v.42bis. PPP, Zmodem, Kermit. Error-correcting code / error-detecting code with retransmission protocol, superimposed on a raw binary channel.
The OSI Network Layer = the layer which turns reliable direct connections between pairs of directly connected endpoints into a network, i.e. a communications medium in which each endpoint can send a packet to another endpoint by relaying its packet to its (directly connected) gateway and providing to the gateway a delivery address on the network. The sender does not have to worry further about the message getting delivered — the network layer provides the necessary routing to deliver the message. Message delivery is not necessarily reliable (delivery is not guaranteed and the sender does not know if it has been delivered). The key characteristics of the network layer are (a) that it is between a sender and an addressee (there is a concept of a network address), and that it is unreliable.
The OSI Transport Layer = the layer which turns an unreliable channel for sending addressed packets into a reliable channel for sending addressed packets. The key characteristics of the transport layer are (a) that it is between a sender and an addressee (there is a concept of a network address), and that it is reliable.
The Internet (IP) and the Ethernet layer are both OSI Network layer protocols, where the IP network layer is layered on top of the Ethernet network layer. The Ethernet layer is not a data link layer.
There is nothing unusual about stacking OSI Layers in a way which doesn't build OSI Layer (n+1) on top of OSI Layer n. PPPoE is an OSI Link Layer (PPP) stacked on top of an OSI Network Layer (Ethernet). ZModem run on a serial line provided by a modem which already provides v.42bis error correction is an OSI Link Layer stacked on top of another OSI Link Layer. ZModem run over ssh is OSI Link Layer run on top of an OSI Application Layer.
To distinguish between the two network layers, the early pioneers of the Internet (who were familiar with the OSI Model) referred to the network layer(s) on top of which the IP protocol operated the network layer, or the network connection layer, and to the new network layer which they were creating, which was connecting existing networks (and network layer protocols) into a bigger network (and more universal network protocol) the inter-network layer.
It is also not the case, as is claimed on many pages in this series that there is no correspondence between the OSI layers and the TCP/IP layers. The layers are clearly defined, and the correspondence is there and it is very clear.
E.g. IP is an OSI Network Layer protocol implemented on top of other OSI Network Layer protocols, such as, e.g. the MAC/Ethernet layer.
I have re-arranged some of the protocols in line with the above definitions, though I think several of them are still in the wrong place.
Tarian.liber ( talk) 01:00, 29 August 2013 (UTC)
Tarian.liber ( talk) 22:21, 3 September 2013 (UTC)
It is difficult to have a discussion if you ignore counter-arguments. I have made several attempts to explain the Wikiquette but you keep violating it. When you get into a discussion like this you cannot expect others to wait half a week for your reply. Ad hominem attacks do not help your position.
Even university libraries don't carry Beauchamp. Unfortunately you won't answer clarifying questions about what he really says either. The two references I gave, in contrast, are reliable beyond doubt and readily available. You're also wrong about history: the OSI reference model does not predate TCP/IP. But this is irrelevant to the discussion. And again, error detection is not reliability.
Your main argument appears to be that there are no addresses at the data-link layer. Here's what the actual OSI standard has to say (ISO/IEC 7498-1, p.46):
"7.6.3.2 In connection-less mode, the facilities provided by the Data Link Layer are:
a) data-link-addresses"
It says nothing about "directly connected". What other argument did I miss? -- EnOreg ( talk) 08:59, 4 September 2013 (UTC)
Tarian, there are two issues here. The first is that this is a template talk page, and that's not where content is being discussed, and not where content decisions are being made. The template collects what the article describes. I don't agree with many of the placements of protocols on particular OSI or TCP/IP layers, but this is not the place to discuss that, and this is not the place to get consensus on content changes.
The second issue is that there are thousands of books about it, and that quite a few of them don't get it quite right. If the definition of the first four layers is in Beauchamp as you quoted it here then this book belongs to that large group; there is almost nothing right in those four layer characterisations, not even the layer names (There's no Transmission Layer). Yes, books are reliable sources but there is no problem providing other books that don't put it that way, as has happened in the article on the OSI model, for instance. Hope this helps, Pgallert ( talk) 11:53, 4 September 2013 (UTC)
And can we get back to the original issue being discussed. So far the quotes do not explicitly say that IEEE 802.3 protocols are in the network layer. In fact, from sources I see that the OSI model was developed from 1977 to 1979 (totally missing from that article, sigh) while 802.3 did not come out until 1983 (although Ethernet of course was done before OSI), so all three (OSI, IEEE and IP protocol suite) were essentially going on in parallel. As a compromise, I would say it might be safe to say that the IEEE (and IP to a lesser extent) protocols do not fit directly into the OSI model, so they should be removed from this template. In fact, the template is not transcluded in the IEEE 802.3 nor IEEE 802.2 articles, which is another good idea to remove them from this template. And eventually we do need to discuss the edits to the OSI model article too which are a bit misleading. For example, the OSI model (or at least the ISO protocol stack that resulted) had both connection-oriented and connectionless network layers. In connection-oriented networks, virtual circuits were the abstraction, not datagrams, which were associated with connectionless networks only. Many (not all certainly) were from the phone companies after all. W Nowicki ( talk) 16:09, 4 September 2013 (UTC)
Sorry, I'm getting a bit forgetful these days and I forgot what my own point about the timeline was, and now I remembered. To those who claim that Ethernet does not define a layer which belongs to OSI Layer 3 (and that the relative timeline of coming into being of OSI and the Internet does not matter), I ask this question: before the Internet came along, which stitched together all the other networks, and introduced an 'inter'-networking network layer on top of the network layer of other networks, and before TCP/IP became standardized, people were already using Ethernet for their networking. So which part of their (our) networking stack formed OSI Layer 3 in those days then? Just answer this question for me, please.
Tarian.liber ( talk) 02:03, 6 September 2013 (UTC)
I see that TLS/SSL is shown in this template as a layer 5 protocol. I think this is misleading. TLS/SSL do not operate at layer 5. In the Transport_Layer_Security article there is a paragraph stating that TLS is initiated at layer 5 and operates at layer 6 and there is an infobox statig that TLS operates at layer 7 - so we are not being consistent. I think the reality is that TLS does not really fall nicely into any layer of the model and I would suggest its clearer to just remove it from this template altogether. Nicholsr ( talk) 17:44, 3 January 2014 (UTC)