Hello,

On 1/24/13 4:34 PM, Andreas Granig wrote:

Hi Daniel,

On 01/24/2013 03:55 PM, Daniel-Constantin Mierla wrote:

...

The latest version has support for using dialog to store the From/To values, so no masking within rr param. It should work fine in your case, I guess.

For earlier version, you can achieve more or less the same by storing from/to values in htable, indexed by call-id.

Thanks for the explanation.

This issue actually happens on our very first SPCE version (2.1), which just runs one kamailio as proxy without any load-balancer and sbc in between the proxy and the called party.

Since 2.2 we use sems as sbc between proxy and lb on the way out to the called party b, so in that case if B sends something odd in the To, it'll be discarded and replaced by the To (or From, depending on the direction) which had been passed from the proxy to the sbc in the initial INVITE.

So that's for example a very good scenario where it pays off to have an SBC in your system :)

there is no need for an sbc and break the call in two legs and drop my cool extensions I have in my softphone.

htable does it very well in this case if you want to store initial values and if the device are rfc3261 compliant and look only at the tags, you can put what so ever crap there.

The comparison is more like: it's better to have an airplane instead of a car to drive on highway because can be done without wearing safety belt, which is required only for take off, landing and turbulence :-).

Cheers, Daniel

Hello,

On 1/24/13 5:25 PM, Andreas Granig wrote:

Hi,

On 01/24/2013 04:49 PM, Daniel-Constantin Mierla wrote:

...

there is no need for an sbc and break the call in two legs and drop my cool extensions I have in my softphone.

What cool extensions would that be? I guess the sems guys would be happy to fix it, if it breaks something unexpectedly.

well, see, you just hit your (business) head! Why I should share with the sems guy the ideas about my cool features? Did google/twitter/facebook/... had to do disclose anything about their ideas to apache devs?!?

With proxy architecture/kamailio new extensions just works fine -- it needs to look at r-uri, route headers and just few other stuff. I can have anything in other headers and in sdp/body, including new brand request methods. It is an open innovation environment.

...

The comparison is more like: it's better to have an airplane instead of a car to drive on highway because can be done without wearing safety belt, which is required only for take off, landing and turbulence :-).

An SBC is rather like an airbag. If done right, you don't even recognize it and in case of an issue it might save your ass. If done wrong, it will blow up in your face while driving 100mph on the highway.

Not quite, airbag is a passive element in the process, it does not help to drive correct or better. I haven't seen airbags on airplanes (bikes, fast trains, hoovers or other transportation engines) :-) and they won't save any*bodypart on real issues there...

The SBC is an anchor in the past, just a pstn element brought to IP to keep RTC evolution slow, in the hope the telcos will control everything and milk a bit more cash on allowing and charging voice minutes only. Their era is pretty much gone, proper RTC platforms will emerge soon from real IP companies that'll give the freedom to build new services on top as needed...

As said in the past, I can understand from the business perspective of "it's what the customer demands", but there is no added value, just more complexity and another point of failure. Transcoding or other media services (e.g., ivr) are the roles of voice application servers.

Cheers, Daniel

Hello,

On 1/24/13 8:27 PM, Andreas Granig wrote:

Hi,

On 01/24/2013 06:35 PM, Daniel-Constantin Mierla wrote:

...

...

What cool extensions would that be? I guess the sems guys would be happy to fix it, if it breaks something unexpectedly.

well, see, you just hit your (business) head! Why I should share with the sems guy the ideas about my cool features? Did google/twitter/facebook/... had to do disclose anything about their ideas to apache devs?!?

With proxy architecture/kamailio new extensions just works fine -- it needs to look at r-uri, route headers and just few other stuff. I can have anything in other headers and in sdp/body, including new brand request methods. It is an open innovation environment.

Let me put it in another way: I'd be very surprised if you can come up with something that you can NOT pass through sems.

do you mean out of the box with the sbc'es from any telecom-style deployment or I have to notify them, write code as the vendor, etc ... for each new bit?!?!? I am not the vendor and the SIP/programmer guy in this discussion, but just the average Joe that bought a new cool smartphone or the erlang guy that developed a new extension to its phone app.

Since you claim that your cool stuff gets broken, I'd appreciate you to come forward with an example, otherwise it's plain FUD.

I think you could really come up with a better demand in this discussion, otherwise is clear misunderstanding of the topic and makes no sense for further debate.

Anyhow, for the peace of your soul, alice and bob have a shared password and want to exchange a private token/data carried with each request in a custom header xyz. The body of this header is set as base64 of the value resulted from encryption of the token with a specific encryption algorithm known only by alice and bob, using the shared password, own via branch parameter value, contact uri, call id and from tag. Let me know how a sbc/b2bua will make that work. I let you disclose it to sems guys so they can be happy fixing this extension to work through sems sbc. Or maybe the FUD is coming from the other direction ...

...

The SBC is an anchor in the past, just a pstn element brought to IP to keep RTC evolution slow, in the hope the telcos will control everything and milk a bit more cash on allowing and charging voice minutes only. Their era is pretty much gone, proper RTC platforms will emerge soon from real IP companies that'll give the freedom to build new services on top as needed...

Future RTC platforms from real IP companies will (and already do) provide web APIs, where you can build fancy applications using HTML5/JS on top. There is even no need for SIP at all to do so, as long as you stay in your walled garden, so there is also no need for a SIP proxy. Just saying.

If you speak about the webrtc, it will have a role on online interactions. But I don't see replacing the telephony system. Nobody will stay with the browser open to be reachable (even less open to several providers). So walled gardens rtc will be as an addition feature to existing walled gardens.

However, if you care about interoperability, you'll also in the future use SIP or XMPP.

At some point (I hope) it will end up in a email-servers-like grid. And I won't care about what is the protocol behind that much...

And then again, you always have the choice in the proxy whether to engage a b2bua/sbc or not, depending on policies and/or particular needs (e.g. for being able to actively engage in established sessions on a signalling- and/or media level).

How, me as the caller, do I have to dial a prefix, add a header, ... to chose a session via sbc or not? Any rfc for that?

...

As said in the past, I can understand from the business perspective of "it's what the customer demands", but there is no added value, just more complexity and another point of failure. Transcoding or other media services (e.g., ivr) are the roles of voice application servers.

That has nothing to do with a business perspective, we're still talking on a technical level. What you're referring to is an approach where people get hammered into their heads from marketing people that regardless of what an RTC system is supposed to do or how it actualy looks like, you need an expensive SBC (coming in a big fancy separate box) in front of it. That's ridiculous, and I'd agree with you here.

However, you've a radical opinion on that, obviously rejecting everything which is not a proxy.

I didn't know freeswitch, asterisk or even sems are proxies in my deployments and use cases, if yes, then I do agree with you. Otherwise they play nice as voice application servers (voicemail, conferencing, transcoding, ...).

From a functional perspective, it makes perfect sense to split call legs in certain scenarios with a b2bua (which is essentially what sbcs are), because it allows to actively engage in established dialogs, which in turn is what you want or need for server-side voice applications. And this is why proxies and sbcs (or b2buas, or however you want to call them) can perfectly work together in a SIP system.

Do you mean, me, as user paying for the RTC service (so we practically talk here about location service, because all is IP), I want the provider to actively engage in my 3d naked hologram call with my doctor? For? Putting pills advertising banners in the middle?

In the end, it just matters which tool you choose for what. Kamailio is a great piece of software, but I'd refrain from using it for just everything, which inevitably results in horrible hacks.

I will definitely not recommend to be used as SBC (b2bua), if you one would need such thing. Also, not for IVR, transcoding, voicemail and few more, but for the rest there it is ... cooking, washing, etc...

For example, why (as a provocative question) would a proxy need a dialog module, if it could just route traffic on a stateless and/or transactional basis, and store additional stuff in Route headers? This module was full of issues for years and still has its shortcomings, because the whole proxy architecture is not designed from the ground up to handle these cases (e.g. it's always tied to tm module).

Dialog module, seen as call stateful proxy, is not much more than a storage for some attributes of the sip dialog used for matching the signaling requests within dialog (callid, tags) and those needed to route for sending byes (routes, contacts). Then has a timer to fire on max duration of the call. Does not care about content of the session, does not care about extra headers, etc...

It is tied on tm to deal easier with reply matching and sending byes. Might not be the case, but having issues can be also a matter of the developer/this particular module design. I started using it when I wrote first significant bunch of code for it, before (and even now quite a lot) I used db based (sql queries on invite, bye, replies, etc... with tables in memory) or htable based active calls monitoring system.

Not sure how many noticed that dispatcher has also an embedded light weight dialog tracking system (for active calls load distribution). Nobody complained about it because (probably) just works.

A b2bua on the other hand does just that. There is no need to do routing decisions, because that's what the proxy is there for, so its main purpose is to handle call state information and (re)act on it accordingly.

A b2bua, as the name says, is two UAs, bridged internally between them. No matter how fancy are at the time of the deployment, the provider will not deploy a new pair next month when I develop a more fancier capability of my UA, or, eventually based on $$$, it will deploy if I ask and disclose what I want to do. As my UA talks to a half of the b2bua, our negotiation ends up to the usage of what both UAs in this leg can do, which sets the list of features I can use with my UA to what the provider's UA can do, even the endpoint I want to talk to has the same UA as mine.

Now, to put it in other words and maybe clarify better. I haven't said that sems (or other media server/pbx/...) is a bad application or cannot be configured/extended to pass through everything know at this moment (which practically then is a proxy architecture, not a b2bua). It can be a better or preferred option to manipulate headers for many, that's great, everyone should use whatsoever they like or feel more confident.

For further clarifications, I used RTC (voice is just a bit there) not Telephony and the SBC is a something built on a b2bua architecture, not some sed-like app used to replace few tokens in headers.

Therefore it's long way to saying I am radical about SBC because I don't see the reasons to use such thing for sip headers manipulation.

At the end, I haven't heard that telephony operators are major players in RTC innovation, but maybe they didn't deployed enough SBCs ... and the baby brother ALGs ...

Cheers, Daniel

Hello,

I expected from the previous email that the conversation makes no sense, because it is somehow a clear misunderstanding. In the initial topic of updating some headers you come up with the idea that (quoted):

"So that's for example a very good scenario where it pays off to have an SBC in your system"

It was not my case in the past 12 years, really, not for such thing, no matter how you want to put it, not even as possible scenario, not at all as a very good one.

And if you suggest that is 'the solution' for fraud preventions, then I am SIP blind, not short sighted. Terminology like saves a*ses, plain FUD or short sighted does not have anything to do with technical arguments, its for throwing in a no-arguments discussion. I guess sems guys are happy coding already...

You divert easily to different use cases of kamailio, which don't have anything to do anymore with "a SBC for updating headers" or "SBC as b2bua". Suddenly is also about gateways between protocols and breaking out, what SBC have to do with these specific elements? Can't there be fraud between two pure IP RTC providers?!?! I know also a sbc can run on separate box with linux, that can provide ssh tunneling if needed, or other value added features such as a web server, which can be a must in a specific operator business plan.

But I said that I refer to proper SIP SBC as the function, not to a specific application/system as a whole which can do something else, ivr, voicemail, etc... or what so ever system that does port forwarding. Now, you come to say that one can interpolate or do derivatives to the application and could get a space shuttle, but it is no more a SBC.

I am really more than happy sems gets what you need and how you wanted, is a cool application, I never said something else. You can ask for license fee refund if you got kamailio for a sbc function and is not :-)

Besides SIP blindness, I am getting also speechless - "any b2bua-like element in general is bad because it limits innovation as a whole is just wrong" - maybe one can explain me how an UA can use any functionality that is not supported in the b2bua, when is in a session with the 1/2 of the b2bua.

No sense for more, back to testing 4.0.0...

Cheers, Daniel

On 1/25/13 12:54 PM, Andreas Granig wrote:

Hi,

On 01/24/2013 11:52 PM, Daniel-Constantin Mierla wrote:

...

...

Since you claim that your cool stuff gets broken, I'd appreciate you to come forward with an example, otherwise it's plain FUD.

I think you could really come up with a better demand in this discussion, otherwise is clear misunderstanding of the topic and makes no sense for further debate.

Anyhow, for the peace of your soul, alice and bob have a shared password and want to exchange a private token/data carried with each request in a custom header xyz. The body of this header is set as base64 of the value resulted from encryption of the token with a specific encryption algorithm known only by alice and bob, using the shared password, own via branch parameter value, contact uri, call id and from tag. Let me know how a sbc/b2bua will make that work. I let you disclose it to sems guys so they can be happy fixing this extension to work through sems sbc. Or maybe the FUD is coming from the other direction ...

Your reasoning goes like this: A proxy allows to pass through any kind of method and any kind of headers and bodies, and is therefore open and good. An sbc blocks unknown methods and headers and bodies and messes with the messages, and is therefore bad.

This is simply not true. Just because the default kamailio config allows this openness doesn't mean that's how all kamailio configs are deployed. It's straight forward to limit message types and to filter messages, and in fact lots of people do this. Now does this make kamailio suddenly bad? At the same time, it's easy to let an sbc pass through unknown message types and not filter the messages, and thus in no way limit the end-to-end communication. Is it then still bad?

In the end, it's the use case that matters. If you're bashing telco-style operators because they're providing PSTN break-outs and bear the risk of getting victims of fraud and therefore are protecting this line of signalling, then this seems a bit short-sighted.

...

...

Future RTC platforms from real IP companies will (and already do) provide web APIs, where you can build fancy applications using HTML5/JS on top. There is even no need for SIP at all to do so, as long as you stay in your walled garden, so there is also no need for a SIP proxy. Just saying.

If you speak about the webrtc, it will have a role on online interactions. But I don't see replacing the telephony system. Nobody will stay with the browser open to be reachable (even less open to several providers). So walled gardens rtc will be as an addition feature to existing walled gardens.

...

However, if you care about interoperability, you'll also in the future use SIP or XMPP.

At some point (I hope) it will end up in a email-servers-like grid. And I won't care about what is the protocol behind that much...

Fully agree. But compared to email, you've different networks in RTC, like SIP, XMPP, SS7, ISDN etc. As long as it stays all-IP and nobody holds up his hands to collect money for such transits or terminations, it's all good, and you as an operator don't have to care about someone abusing your service (it's an annoyance which you better stop at some point, but it doesn't cost you thousands of dollars per hour/day/whatever). However, these business models charging for such communications won't go away any time soon, and I as an end-user actually appreciate to be able to call also mobile numbers, even though the feature set is limited to what we had for the last 100 years. The whole world is going through a transition period from circuit switched networks to packet switched networks, and during this period, you as an operator better protect your assets as long as you get charged for it from up-stream.

But again, this is just ONE use case of an sbc, and it doesn't mean your end-to-end communication gets stripped down to the bare basics by definiton.

...

...

From a functional perspective, it makes perfect sense to split call legs in certain scenarios with a b2bua (which is essentially what sbcs are), because it allows to actively engage in established dialogs, which in turn is what you want or need for server-side voice applications. And this is why proxies and sbcs (or b2buas, or however you want to call them) can perfectly work together in a SIP system.

Do you mean, me, as user paying for the RTC service (so we practically talk here about location service, because all is IP), I want the provider to actively engage in my 3d naked hologram call with my doctor? For? Putting pills advertising banners in the middle?

Methods for secure end-to-end communication do exist, it's a matter of providing endpoints which properly implement them and let the users know if the operators tinkered with their communication channel.

This is not specific to sbcs though, as you can engage in a dialog with kamailio as well (like dialog/uac for example). It's a matter of how far you want to push your proxy to do certain tasks. And for some tasks, a b2bua element is better suited than a proxy by design. This doesn't mean you can't do things both ways.

As an operator, it comes down to knowing your scenarios and choosing the right tools for the right job. Saying that an sbc or any b2bua-like element in general is bad because it limits innovation as a whole is just wrong.

...

At the end, I haven't heard that telephony operators are major players in RTC innovation, but maybe they didn't deployed enough SBCs ... and the baby brother ALGs ...

The big telco operators have a much different agenda than small and innovating startups. Just because the big telcos use sbcs doesn't mean that sbcs prevent innovation. It's their mind and business plan which does, you can't blame it on technology.

Andreas

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SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users@lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

On 1/25/13 8:54 AM, Alex Balashov wrote:

On 01/25/2013 08:51 AM, Daniel-Constantin Mierla wrote:

...

No sense for more, back to testing 4.0.0...

Maybe so, but I for one thought it was quite an interesting discussion. :-)

I'm more interested in the refund idea. I think I finally found the best way I can contribute to the project; refund administrator.