Re: [P2PSIP] Choice of STUN peer or TURN peer
"Dan Wing" <dwing@cisco.com> Sat, 02 February 2008 03:26 UTC
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From: Dan Wing <dwing@cisco.com>
To: 'JiangXingFeng' <jiang.x.f@huawei.com>, 'Bruce Lowekamp' <lowekamp@sipeerior.com>
References: <077401c864f7$605bfc80$c4f0200a@cisco.com> <002c01c8654a$d9800450$2d09a40a@china.huawei.com>
Date: Fri, 01 Feb 2008 19:27:56 -0800
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Cc: 'P2PSIP Mailing List' <p2psip@ietf.org>
Subject: Re: [P2PSIP] Choice of STUN peer or TURN peer
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> -----Original Message----- > From: JiangXingFeng [mailto:jiang.x.f@huawei.com] > Sent: Friday, February 01, 2008 7:23 PM > To: 'Dan Wing'; 'Bruce Lowekamp' > Cc: 'P2PSIP Mailing List' > Subject: RE: [P2PSIP] Choice of STUN peer or TURN peer > > > TURN client Peer X STUN server NAT TURN server > | | | | | > 1. |-------------------->|---Give me a Turn Address > --------->|----------------->| > 2. |<-----------------STUN > Request----------| > 3. |-------------------STUN Response------>| > 4. |<--------------------|<---------here is your TURN > address-------------------| > Figure 1: message flow to get a TURN address > > As Bruce suggested that message 1 and 4 will be routed > through the overlay. I don't believe that will work; part of what causes TURN to be an effective NAT relay is that the TURN client sends a packet directly to the TURN server's publicly-routable transport address. The side effect of the TURN client doing that is that the TURN client's (evil, nasty) NAT opens pinholes to communicate bi-directionally with the TURN server's transport address. ("evil, nasty" meaning symmetric or port-restricted, using RFC3489 definitions.) -d > So here, we assume the Peer X is the neighbor peer to the TURN server. > Message 4 will return to TURN client by traversing Peer X or > not. Here, we > assume the NAT has an address-dependent filtering behavior > which most NATs > have. > > When TURN servers receives message 1 through the overlay, it > will set the > Internal Remote transport address as Peer X's transport > address. Then send > message back to the Internal Remote transport address in its Internal > 5-tuple. Then NAT will open a port for Peer X. > > TURN client Peer Y Peer B NAT TURN server > | | | | | > 5.|--------------------- ->|-------Send > Indication---------------------------->| > 6. |----Binding Request------- > | (filtered by > the NAT) > 7. > 8. > Figure 2 message flow for connectivity > check in ICE > > When TURN client wants to communicate with Peer B which is > also behind the > NAT (the NAT in front of the Peer B is ignored in the Figure > 2), it should > use overlay routing to exchange their candidates. > We assume the candidate pair from TURN client is {relayed > candidate, server > reflexive candidate of Peer B} > So In message 5, TURN client will send a binding message which will be > encapsulate in the Send Indication and the message will be > sent to TURN > server. > There are two ways which could be used to send the message: > 1. directly, due to NAT has a address-dependent filtering > behavior, NAT will > filter the message; > 2. through the overlay. yes, the message could arrive at the > TURN server. > But you know, overlay topology is changing and the immediate > peer to TURN > server in message 5 may not be Peer X any more, may be other > peer, such as > Peer Y. For TURN server, it will check its association, and > find no matched > internal 5-tuple, because Internal Remoter Transport address has been > changed. It will be discarded by the TURN server. > > On the other hand, Peer B will send a Binding request to TURN client's > relayed address, whose destination is TURN server. But it will also be > filtered by the NAT due to its filtering behavior. > > To be honest, I am not very familiar with ICE. If there is > something wrong, > please point it out. Thanks. > > JiangXingFeng > _______________________________________________ P2PSIP mailing list P2PSIP@ietf.org http://www.ietf.org/mailman/listinfo/p2psip
- RE: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- RE: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- RE: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- Re: [P2PSIP] Choice of STUN peer or TURN peer Bruce Lowekamp
- [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- RE: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- RE: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- RE: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- RE: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- Re: [P2PSIP] Choice of STUN peer or TURN peer Bruce Lowekamp
- RE: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- RE: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- RE: [P2PSIP] Choice of STUN peer or TURN peer Henry Sinnreich
- RE: [P2PSIP] Choice of STUN peer or TURN peer Jerry Yin
- RE: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- RE: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- RE: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- RE: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- RE: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- Re: [P2PSIP] Choice of STUN peer or TURN peer Cullen Jennings
- Re: [P2PSIP] Choice of STUN peer or TURN peer Henry Sinnreich
- Re: [P2PSIP] Choice of STUN peer or TURN peer Song Yongchao
- Re: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- Re: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- Re: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- Re: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- Re: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- Re: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- Re: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- Re: [P2PSIP] Choice of STUN peer or TURN peer Cullen Jennings
- Re: [P2PSIP] Choice of STUN peer or TURN peer Dan Wing
- Re: [P2PSIP] Choice of STUN peer or TURN peer JiangXingFeng
- Re: [P2PSIP] Choice of STUN peer or TURN peer Bruce Lowekamp
- Re: [P2PSIP] Choice of STUN peer or TURN peer Francois Audet