SCTP 1

[@sohamsa]

Really great overview for SCTP. Interestingly SCTP was co-authored / RFCed by our group at Motorola

[@QuadraticSquared]

The issue there, Kamesh, is that the application has no awareness to switch in that way. SCTP knows about "paths" only in the sense that it knows which local and remote IPs can ultimately talk to each other, but it doesn't know about (and cannot influence) the routing decisions made by IP infrastructure between those source and destination IPs. The question "How do I route toward 1.1.1.1?" is decided by the IP network, whereas the question "Should I send to 1.1.1.1, or should I send to 2.2.2.2?" is decided by SCTP failover. So in that diagram at 27:46, SCTP would lose all of *its* paths because all destination IPs are reached via the same physical link, and SCTP has no means of influencing failover to the other physical link (from SCTP's perspective, all redundancy has failed and the assocation is down). It's not that there's no redundancy, but it's active/passive and dependent on IP infrastructure failover no matter how you have configured SCTP, which may be counter-intuitive if you're looking at purely from an application standpoint without understanding how the underlying IP network influences this scenario. Note: This is a comment since I wanted to reply to the question and Google's not letting my 'reply' to that question for some reason.

[@kushkaul]

***** Thanks a lot. I really had lot of fun going through all your videos today. Great work!

[@QuadraticSquared]

Kamesh Kaul Thanks! :)

[@adrijachakraborty2316]

Came. Saw what a great explanation this was. Loved learning. Subscribed. Simple!

[@tennis207]

Contrasting with TCP is very helpful to understand the value added of this protocol

[@zahidadeel25]

Thanks a lot dear. Your tutorials are really helpful :)

[@juliosantisteban8452]

min 13:45 SCTP is not an RDT 100%, but SCTP has to modes UDP and RDT, which one you are talking about?

[@QuadraticSquared]

UDP is an alternate transport protocol to SCTP, not a "mode" of SCTP. That part of the video was discussing TSN acknowledgement concepts in SCTP RFC 4960, described categorically (eg: section 1.5.4). Can you clarify what you are referring to? "RDT" is not a term found in the SCTP RFC, and UDP is a real thing but a completely different protocol to SCTP.

[@juliosantisteban8452]

Reliable Data Transfer (RDT) , SCTP implements RDT, but you mention that SCTP allows to skip msg 26 which will break the RDT protocol. RFC 4960 also mention in 6.7 that gaps are reported until is received as is describe in 6.2.1.

[@QuadraticSquared]

@@juliosantisteban8452 I did not say that SCTP "allows" to skip chunk 26, but rather that data chunk 26 could potentially be lost, where I then described SCTP's duplicate-ack mechanism which allows the receiver to indicate what needs to be retransmitted. I think the problem here is interpretation. Retransmissions and lost packets aren't "allowed" to happen by the protocol, but the protocol has mechanisms to deal with these unwanted things happening.

[@juliosantisteban8452]

​@@QuadraticSquared I found the video very useful, but I still I have some doubts perhaps as you mention interpretation is the key. nevertheless, I will recommend the video to my students., cheers.

[@kushkaul]

At 27:46 once the least cost path link fails, wouldn't the application just switch over to the path with cost of 1000 instead? Isn't something better than nothing?

[@QuadraticSquared]

The application can control whether to try to use IP 3.3.3.3, or 4.4.4.4. If the network can't reach either of them, because the routers are sending all traffic to both IP's on the lower-cost link, the application can't save it. In that scenario, both 3.3.3.3 and 4.4.4.4 would come back *after* the network re-converged. That usually happens quickly for a routing protocol like OSPF (can be sub-second), but it can also be long enough to drop the SCTP association, which is the danger.

[@hrishikeshmore1936]

Can you make a video on running different sctp protocol

[@oluwatobilobaayofe6303]

Thanks for this video. It's quite unfortunate I have had this notion that SCTP is used for real-time communications such as voice and video calls/conferencing. Perhaps I mislead myself based on the fact the protocol is being said to be usually employed in telecom networks and my assumption was basically voice calls without considering data networks traverses through the network.

[@sypher4912]

Yeah, I disagree with his take. 5G LTE networking uses SCTP transport for the GTP-u tunneling protocol.

[@arunthakur8085]

Hi,Russell i saw your ss7 and sigtran video.It was great.I was wondering if you could upload video on Diameter protocol.

[@QuadraticSquared]

Thanks Arun, Diameter is something I'm hoping to cover soon actually, though there are a few different applications worth covering (S6a/d, credit control, policy control, diameter routing in general). Might become a few topics.

[@arunthakur8085]

***** thanks and i am hoping to see diameter soon. Also the topics u mentioned i.e diameter routing,credit control,policy control are worth studying. so i am hoping to see these topics THANKS once again

[@moatazalsbak984]

very good , can i download the soft copy of this material

[@gavenchan]

Very good explanation. Thanks!

[@lindhe]

Very good explanation. Thanks. :)

[@ivanki731]

awesome vid

[@sassynatan]

At Last some good overview about SCTP

[@gavenchan]

Thank you so much for sharing this

[@azizazaied9677]

Hi, thank you very much i'm a master student i need to simulate sctp and make update at the code source so, can you help me i'm blocked how to start i will very grateful

[@QuadraticSquared]

You need to write an SCTP stack from scratch, or you just need to work with one? I'd suggest checking out libsctp if it's the second. If you need to write the whole stack, the only reference I can think to give would be the SCTP RFC itself.

[@azizazaied9677]

thanks a lot for your response :) have you worked with ns2 before ? i will just exploit an existing stack

[@flytoash]

Good Video

[@prakashn7295]

thanks. Its usefull

[@newkool100]

thanks a lot...

[@engihabit]

Great job and well done thank you .... may I have your email please ? I would like asking you few questions if you do not mind ?

[@QuadraticSquared]

Thanks. And sure, it's in the video actually: [e-mail]

[@cdsaamer]

Hi russell thank's for your videos it help allot can you email me this ppt slides please just is it possible ?