I would like to clarify that the endpoint to endpoint transactions (peer to peer transaction) of two PCIE endpoints behind a PCIE switch are not forwarded to the root complex.
I googled around and understand that if the transaction from Endpoint #1 targeted to the PCIE address space which the root port assigned to the Endpoint #2, the switch will forward the transaction to the downstream port where Endpoint #2 located.
Please correct me if I misunderstand this point. Is this forwarding feature mandatory according to the PCIE spec or implementation-specific?
At first, if a PCIe Switch supports Access Control Services(ACS) and the host software configures the Switch to redirect a P2P transaction to upstream, the Switch forwards the transaction towards Root Complex. So there is a case that a P2P transaction is forwarded to upstream.
If the Switch does not support ACS or the host software disables ACS, the PCIe Switch will forward a P2P transaction to downstream directly. I think this routing is mandatory because the internal bridges of the PCI Switch should perform as conventional PCI-PCI bridges.
Here are some references:
If you can access the latest PCIe Specification, you can read about ACS capability in the spec. But if you are not a member, you can read the ECN of ACS because it is public, which will also be helpful. PDF
Intel provides the useful document that describes why ACS is required.
Here VMware requests that the PCIe Switch must support ACS to use PCI Passthrough.
Related
Is there any protocol, API or software in existence that can send data/IM/etc directly from one device to another with no server?
Can you not use HTTP GET/POST/DELETE directly between two devices when their device data is known to the user(s)?
I would very much like to know if there is ANY software/protocols that can do this.
thank you!
The internet is build on the Internet Protocol suite. This suite has 5 different layers of protocols: The physical layer, the link layer, the network layer, the transport layer and the application layer. Each depends on the one before.
If you just use the browser, by default HTTP (application layer) is used, which relies on TCP (transport layer), which relies on IP (v4 or v6, network layer), which relies on ethernet (link layer), which finally relies on the actual cable that's plugged into your computer (for WiFi, the first three are the same but the last two differ if I'm not mistaken).
Now to your question: Is there any protocol, API or software in existence that can send data/IM/etc directly from one device to another with no server?
Yes there is. I suggest you start looking at protocols that are in the application layer. To highlight a few standards next to HTTP(S): FTP is for file transfer, IMAP is for emails clients, SMTP is for email servers and SSH is a secure shell which can also be used to tunnel data through.
For your specific case, I think either FTP (FTPS if you want it over SSL), or SSH can be a solution, but it's hard to know for sure without the specifics.
The only thing that these protocols have in common is that one of the two computers will act like server and the other computer as client. This has as downside that port-forwarding might be necessary.
If you've chosen the protocol you'd like to use, then you're up for the next step, selecting a program that can do that for you. For HTTP(S), I'd recommend Apache. If you're using Linux and chose SSH, then you're in luck, there is a build in SSH server in Linux, you can use that. For other protocols, you might just want to search yourself, as I do not have any suggestions.
I hope this answers most of your questions!
Desirius
In browser context, WebRTC is probably what you are looking for: It allows user to user communications.
https://en.wikipedia.org/wiki/WebRTC
https://webrtc.org/
I would like to know whether NFC P2P requires something like a MAC address that needs to be configured to be used for identification while creating a link layer connection or maybe even at transport layer connection.
I could see some details in specifications (ISO/IEC 18092) related to IDs being random values that are generated and maintained (per connection) for link layer connections.
I would be thankful if someone can please advice me on where can I find more details on the same or provide some light into how NFC devices are uniquely identified in P2P communications.
NFC P2P does not require a MAC address or comparable mechanism to address a communication partner on the network. It is purely a one-to-one network and the communication partner is uniquely given by this association. A scenario where communication would only be possible with selected peers is not foreseen on the link level, the link is intended to work with any peer. Device identifications must be implemented in application protocols, when needed. Unique identification of a peer device on the link level would raise serious privacy concerns while there is no technical need.
Sip (session initiation protocol) does not understand websocket so we need sip proxy which is basically a translator between sip and websocket.
i am following this architecture for sip handshaking with web socket. I have few questions
which sip proxy must be used to make audio and video call. and in the Gateway to SIP module i am using ASTERISK. how asterisk can be used for video call is there any codec available for video call? Please share some useful links.
Your kind answers will be highly appreciated.
Check out http://jssip.net. They provide a javascript API which uses SIP over WebSocket for client-side and they also have a SIP proxy and server (also works with Asterisk,Kamailio). They are the authors of RFC7118 "The WebSocket Protocol as a Transport for the Session Initiation Protocol (SIP)".
that s only one way to do it. There are many ways.
you have to distinguish between the signaling path and the media path
on the signaling path, you have to choose a signalling protocol and corresponding transport protocol. A browser can use web socket for transport and sip for the protocol as far as signaling is concerned. On the legacy SIP side, you need SID over UDP, there is a need to change the transport of the signaling, not the protocol of the signaling.
On the media path, you have two problems, the encryption and the codec. The encryption is mandatory in webrtc and not in SIP. You need a B2BUA to make the transition between both words.
on the codec side, you either choose an overlapping codec between both words, or you have to transcode. The use of a media server seems mandatory here. If you have multiple parties in a conference, you will need to mix the audio and compose the video to send it to legacy SIP, in which case your media server should be an MCU.
Eventually, you also have a discovery and identity problem. During the original handshake, SIP is expecting a user ID and a domain (which is either a DNS entry or a fixed IP) while webRTC is using ICE. Here again, it is very likely that you need to use a B2BUA to bridge both world.
Asterisk/kamailio/freeswitch are likely to handle most of the above for the simple cases (1 to 1, audio). For anything complicated, you're on your own. You might want to look at respoke.io that was made by digium, the company behind asterisk.
Can one say an architecture using websocket technology is based on client-server model?
By definition The client–server model is a distributed application structure that partitions tasks or workloads between the providers of a resource or service, called servers, and service requesters, called clients.
However using the websocket technology, two endpoints can both act as providers of a resource or service and also service requesters.
Say for example in a situation where the two endpoints are: a user device with a gps sensor and a computer machine, both connected in the network using websocket. And the computer machine is sending requests to obtain the current position of the user device (here the user device is acting as a resource provider and the computer machine as a requester). Later on the user device uses the websocket connection to request all its positions on the last 5 days to the computer machine (now the user device is acting as the requester and the computer machine as the resource provider).
If both devices can act as resource provider and requester, are they complying with the client-server model definition or not?
No it's not breaking anything. End Points are not devices they are connections between devices.
ie if we were asking each other questions and answering them
There would two connections between two 'devices' giving four endpoints. You to me and me to you. No conflict.
TCP is full duplex capable, and particularly WebSockets are full duplex. As #Tony Hopkinson pointed out, there is no conflict at all. This means, you can write and read at the same time.
WebSockets are push technology, more suited for events; while usual request-response models are pull technology.
You can have both client-server or peer to peer architectures with push approach, but pull is the normal choice for pull architectures.
Peer-to-peer Architecture: A peer-to-peer network is designed
around the notion of equal peer nodes simultaneously functioning as
both "clients" and "servers" to the other nodes on the network. This
model of network arrangement differs from the client–server model
where communication is usually to and from a central server. A typical
example of a file transfer that uses the client-server model is the
File Transfer Protocol (FTP) service in which the client and server
programs are distinct: the clients initiate the transfer, and the
servers satisfy these requests.
You can also provide a mix of peer-to-peer and client-server. For example, you can do requests via WebSocket, and at the same time, the server could send updates on its own initiative. I don't understand what you mean with "breaking the model". WebSocket is just a communication channel. In your app both models can coexists and use the same communication channel.
I know that out of the box that GridGain connects to the other clients through multicast, but is there a way to configure GridGain to accept connections outside of the local network? Also is there a way to enable encryption for the communication as well?
The Disovery SPI and Communication SPI allows you to plug alternative discovery and communication mechanisms.
For more detail, refer to the comprehensive API documentation (GridGain 3).
This is necessary on Amazon EC2, which doesn't support multicast. Here's an article discussing this setup.
Multicast only works well within a certain network segment (and in some cases this isn't even allowed for security reasons). So if you want to connect nodes to your grid that are outside your local network you have to resort to other transports such as JMS or mail (if performance is an issue you might get it away with unicast/static ip's and JGroups).
I think that encryption is possible with both the JMS and mail transport, depending on your message broker and mail setup.