Comments on: SIP and Skype, P2P and Supernodes – what a melee http://blog.roychowdhury.org/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/ Tue, 20 Dec 2011 10:18:41 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Arjun http://blog.roychowdhury.org/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/comment-page-1/#comment-52 Arjun Wed, 04 Oct 2006 17:51:00 +0000 http://iconverged.wordpress.com/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/#comment-52 thanks for the confirmation, Buda. The text does not really say that no node behind a NAT can be a supernode. It says no node which is unable to receive inbound connections (with NAT as one possible example) will not be an SN. This is what I thought - because being behind a NAT does not necessarily mean it cannot accept inbound connections - it depends on how the NAT device is configured, and its type. thanks for the confirmation, Buda. The text does not really say that no node behind a NAT can be a supernode. It says no node which is unable to receive inbound connections (with NAT as one possible example) will not be an SN. This is what I thought – because being behind a NAT does not necessarily mean it cannot accept inbound connections – it depends on how the NAT device is configured, and its type.

]]> By: Buda http://blog.roychowdhury.org/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/comment-page-1/#comment-53 Buda Wed, 04 Oct 2006 15:01:00 +0000 http://iconverged.wordpress.com/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/#comment-53 You got that right, the keywords are "unable to receive inbound network connection". SInce there are lots of NAT traveresal techniques and lots of NAT enabled network devices I think we can presume that NAT won't be a problem now or in the near future. Also I find the use of SuperNodes for VoIP a feasible idea, because of the constant growth of a CPU/Hardware power, while the VoIP requirements are already set and is not likely to grow much. You got that right, the keywords are “unable to receive inbound network connection”. SInce there are lots of NAT traveresal techniques and lots of NAT enabled network devices I think we can presume that NAT won’t be a problem now or in the near future. Also I find the use of SuperNodes for VoIP a feasible idea, because of the constant growth of a CPU/Hardware power, while the VoIP requirements are already set and is not likely to grow much.

]]> By: Buda http://blog.roychowdhury.org/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/comment-page-1/#comment-51 Buda Wed, 04 Oct 2006 13:33:00 +0000 http://iconverged.wordpress.com/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/#comment-51 Quote from "Skype Guide for Network Administrators - edition 1.0.1"<br/>http://www.skype.com/security/guide-for-network-admins.pdf#search=%22supernode%20voip%22<br/>"When a Skype client becomes a supernode, it accepts network connections from a<br/>small number of other Skype users for the purpose of maintaining the accuracy of<br/>the Global Index. Although the supernode activity is entirely transparent to the user,<br/>a Skype client that is unable to receive inbound network connections (such as a user<br/>behind a NAT or firewall) will never become eligible to become a supernode nor will it<br/>ever be asked to relay a third party’s traffic." Quote from “Skype Guide for Network Administrators – edition 1.0.1″
http://www.skype.com/security/guide-for-network-admins.pdf#search=%22supernode%20voip%22
“When a Skype client becomes a supernode, it accepts network connections from a
small number of other Skype users for the purpose of maintaining the accuracy of
the Global Index. Although the supernode activity is entirely transparent to the user,
a Skype client that is unable to receive inbound network connections (such as a user
behind a NAT or firewall) will never become eligible to become a supernode nor will it
ever be asked to relay a third party’s traffic.”

]]> By: Arjun http://blog.roychowdhury.org/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/comment-page-1/#comment-50 Arjun Tue, 03 Oct 2006 16:10:00 +0000 http://iconverged.wordpress.com/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/#comment-50 Julian, thanks for the commentary. I am guessing that your comment on a node behind a NAT never being a sn is specific to skype ? That is interesting. Could you confirm this ?<br/><br/>Finally, unfortunately, the problem of voicemail may not be as simple as storing in locally. Consider the case where A calls B and B is offline. Now A goes for a vacation, and B comes online the next day. Then, in this case, B will have to wait for the voicemail till A gets back on. Julian, thanks for the commentary. I am guessing that your comment on a node behind a NAT never being a sn is specific to skype ? That is interesting. Could you confirm this ?

Finally, unfortunately, the problem of voicemail may not be as simple as storing in locally. Consider the case where A calls B and B is offline. Now A goes for a vacation, and B comes online the next day. Then, in this case, B will have to wait for the voicemail till A gets back on.

]]> By: Julian http://blog.roychowdhury.org/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/comment-page-1/#comment-49 Julian Tue, 03 Oct 2006 07:54:00 +0000 http://iconverged.wordpress.com/2006/10/02/sip-and-skype-p2p-and-supernodes-what-a-melee/#comment-49 Great post. There's a surprising amount of FUD around Skype and Supernodes that needs dispelling. Not least is that a PC behind a firewall or NAT *WILL NEVER* be a supernode which gives the lie to "Skype will use your bandwidth"<br/><br/>There's a bit more analysis to do here about approaches to NAT-firewall busting in P2P networks and VoIP. It's not clear to me that media needs to be relayed. Although an intermediary Supernode is required during connection setup between two devices behind NAT.<br/><br/>There's a simple solution to voicemail and text's to nodes off line. That's to store it locally and deliver it when the other party comes on line. You don't need central storage, you just need delayed delivery. Great post. There’s a surprising amount of FUD around Skype and Supernodes that needs dispelling. Not least is that a PC behind a firewall or NAT *WILL NEVER* be a supernode which gives the lie to “Skype will use your bandwidth”

There’s a bit more analysis to do here about approaches to NAT-firewall busting in P2P networks and VoIP. It’s not clear to me that media needs to be relayed. Although an intermediary Supernode is required during connection setup between two devices behind NAT.

There’s a simple solution to voicemail and text’s to nodes off line. That’s to store it locally and deliver it when the other party comes on line. You don’t need central storage, you just need delayed delivery.

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