2012.5.17

Review of the literature :

VoCCN:

Voice-over Content-Centric Networks

Takashima DaikiWaseda University, Japan

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Outline

1. Introduction

2. VoIP background

3. VoCCN architecture

-VoCCN/VoIP Interoperability

4. Simulation

5. Conclusion

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IntroductionFact: There is widespread agreement that content should have a more central role in future network architectures than the Internet’s current host-to-host conversation model.

Goal: To investigate Voice Over CCN – a real-time, conversational, telephony application over Content-Centric Networking (CCN).

Doubt: How well the idea fits more conversational traffic such as email, e-commerce transactions or VoIP?

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phone call

Figure 1: Use case of Voice-over-IP

Background (1) ~VoIP~Voice over Internet Protocol (VoIP) is dominant open protocol for Internet telephony.

When making a phone call, VoIP phones set up a signaling path by using the Session Initiation Protocol (SIP).

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As VoIP endpoints are often mobile, signaling path exchanges are mediated by VoIP that receive and forward messages on behalf of their client endpoints.

Figure 2: Voice-over-IP data flows.

Background (2) ~SIP~

5/13Figure 3: Sequence diagram of SIP INVITE message.

INVITE sip:bob@parc.com SIP/2.0Via: SIP/2.0/CCN parc.com:5060From: Alice Briggs <sip:alice@ccnx.org>To: Bob Jacobs <sip:bob@parc.com>Call-ID: 1911287229CSeq: 20 INVITEContent-Type: application/sdpMax-Forwards: 70User-Agent: Linphone/3.0.0 (eXosip2/3.1.0)Subject: Phone callExpires: 120Content-Length: 1477[...o=alice 123456 654321 IN IP4 13.2.117.34c=IN IP4 13.2.117.34a=key-mgmt: mikey AQQFgE3dV+ACAA...m=audio 7078 RTP/AVP 111 110 0 3 8 101...]

Figure 4: Example of SIP INVITE message.

① INVITE② INVITE

④ INVITE③ 100 Trying⑤ 100 Trying ⑥ 180

Ringing⑦ 180 Ringing⑧ 180

Ringing⑨ 200 OK

⑩ 200 OK⑪ 200 OK

⑫ ACK (session-establishment is accepted)

Session is established (conversation is done)

⑬ BYE(session disconnect request)

⑭ 200 OK (session disconnect)

Aliceccnx.org

proxyparc.com

proxy Bob

Background (3) ~Mismatch in VoIP~VoIP Signaling and Media paths result from a mismatch between the user’s goal and the network’s meaning of achieving it.Alice simply wants to talk to Bob but the network requires that the communication be addressed to the IP address of Bob’s phone.

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One strong point of content-oriented networking is that this translation (typically referred to as middleware) is not needed.

Figure 2: Voice-over-IP data flows.

VoCCN architecture (1)

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Figure 5: Voice-over-CCN data flows.

A caller maps a SIP INVITE into an Interest packet asking for new content from callee, which generates a piece of Data with the requested name containing the SIP response, thus completing SIP signaling in a single round trip.

Challenges:

・ Support service rendezvous: request a connection and get a confirmation response.

・ On-demand publishing is needed: request data that was not published yet.

・ Transition phase: from rendezvous to a bi-directional conversation.

Inline message security:

・ Caller: encrypt and authenticate SIP invite using random-Inline message encriptation generated symmetric key (sk)

・ Caller: encrypt sk using callee’s public key (pk B)

・ Callee: decrypt interest using his/her private key

・ Callee: uses sk to verify and decrypt SIP invite message

VoCCN architecture (2)

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Figure 6: Protocol exchange.

Componets of Interest

VoCCN/VoIP Interoperability

The VoCCN/VoIP proxy serves as the SIP proxy for external inbound VoIP calls, and translates from VoIP packets (SIP and SRTP) to VoCCN packets and vice versa.

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The proxy then performs the CCN-specific parts of the call on behalf of the VoIP client – generating and sending an Interest in the next packet of the exchange.

The proxy examines a VoIP packet and generates a corresponding CCN packet whose name is determined based on information in the original inbound packet header.

Fig 7.VoCCN/VoIP Interoperability

VoIP VoCCN

Media Path

Signaling and Media Path

Signaling Path VoIP-VoCCN gateway

To evaluate CCN’s ability to support timely delivery or realtime data the authors looked at the packet arrival times for their VoCCN implementation.

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・ Proof-of-concept of real-time CCN

・ Extension of Linux VoIP phone (libeXoSIP, liboRTP)

・ Open CCN toolkit (CCNx): routers run on endpoints.

・ Support multi-point routing (mobility)

・ Easy to build advanced services (e.g. conference calls)

Simulation (1)

Simulation (2)

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LinPhone Packet Interarrival Time

Packet interarrival Time (ms)

CD

F:

Pro

port

ion o

f Pack

ets

CCN LinPhone - EncryptedStock LinPhone

The VoCCN call has slightly fewer packet. With almost equal delivery performance, VoCCN and VoIP have same call quality.

Figure 4: Cumulative distribution of inter-packet intervals, or jitter, for a 10-minute voice call.

Limitations/Open Issues

・ Constructable names: flexibility may require partial names that are not unique

・ Pipeline of Interest packets: not proved to perform

Performance for a 10 minutes conversation:

・ More packets below the expected inter-packet interval

・ Small number of long-interval packets

・ No packets loss for both cases

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・ CCN can not only move

content scalably and efficiently, they can also implement IP-like conversational services like voice calls, email or transactions.

・ Voice-over-CCN is functionally and performance equivalent to Voice-over-IP.

・ It is more simpler in architecture, implementation and configuration.

・ VoCCN is completely interoperable with VoIP via simple, stateless gateways.

Conclusion

[1] V.Jacobson, D. K. Smetters, N. H. Briggs, M. F. Plass, P. Stewart, J. D. Thornton, and R. L. Braynard, “VoCCN: Voice-over Content-Centric Networks,” Rome, Italy. , 2009.

[2] Project CCNx . http://www.ccnx.org, Sep.2009.

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Reference