Transcript VoCCN: Voice-over Content

Review of the literature :
VoCCN:
Voice-over Content-Centric Networks
Takashima Daiki
Waseda University, Japan
2012.5.17
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Outline
1. Introduction
2. VoIP background
3. VoCCN architecture
-VoCCN/VoIP Interoperability
4. Simulation
5. Conclusion
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Introduction
Fact: 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.
Doubt: How well the idea fits more conversational traffic such as
email, e-commerce transactions or VoIP?
phone call
Figure 1: Use case of Voice-over-IP
Goal: To investigate Voice Over CCN – a real-time, conversational,
telephony application over Content-Centric Networking (CCN).
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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).
Figure 2: Voice-over-IP data flows.
As VoIP endpoints are often mobile, signaling path exchanges are
mediated by VoIP that receive and forward messages on behalf of
their client endpoints.
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Background (2) ~SIP~
INVITE sip:[email protected] SIP/2.0
Via: SIP/2.0/CCN parc.com:5060
From: Alice Briggs <sip:[email protected]>
To: Bob Jacobs <sip:[email protected]>
Call-ID: 1911287229
CSeq: 20 INVITE
ccnx.org
parc.com
Alice
proxy
Bob Content-Type: application/sdp
proxy
Max-Forwards: 70
① INVITE
② INVITE
User-Agent: Linphone/3.0.0 (eXosip2/3.1.0)
③ 100 Trying
Subject: Phone call
④ INVITE
Expires: 120
⑤ 100 Trying
⑥ 180 Ringing Content-Length: 1477
⑦ 180 Ringing
[...
⑧ 180 Ringing
⑨ 200 OK
o=alice 123456 654321 IN IP4 13.2.117.34
⑩ 200 OK
c=IN IP4 13.2.117.34
⑪ 200 OK
a=key-mgmt: mikey AQQFgE3dV+ACAA...
m=audio 7078 RTP/AVP 111 110 0 3 8 101
⑫ ACK (session-establishment is accepted)
...]
Figure 4: Example of SIP INVITE message.
Session is established (conversation is done)
⑬ BYE(session disconnect request)
⑭ 200 OK (session disconnect)
Figure 3: Sequence diagram of SIP INVITE message.
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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.
Figure 2: Voice-over-IP data flows.
One strong point of content-oriented networking is that this
translation (typically referred to as middleware) is not needed.
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VoCCN architecture (1)
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.
Figure 5: Voice-over-CCN data flows.
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.
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VoCCN architecture (2)
Figure 6: Protocol exchange.
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
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Componets of
Interest
VoCCN/VoIP Interoperability
VoIP
VoCCN
VoIP-VoCCN gateway
Signaling Path
Signaling and Media Path
Media Path
Fig 7.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.
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.
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.
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Simulation (1)
・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)
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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Simulation (2)
CDF: Proportion of Packets
LinPhone Packet Interarrival Time
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
Stock LinPhone
CCN LinPhone - Encrypted
Packet interarrival Time (ms)
Limitations/Open Issues
・Constructable names: flexibility may
require partial names that are not unique
Figure 4: Cumulative distribution of inter-packet ・ Pipeline of Interest packets: not
intervals, or jitter, for a 10-minute voice call.
proved to perform
The VoCCN call has slightly fewer packet. With almost equal
delivery performance, VoCCN and VoIP have same call quality.
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Conclusion
・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.
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Reference
[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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