Network Working Group S. Jeong Internet-Draft ETRI Intended status: Informational February 18, 2013 Expires: August 22, 2013 Network Proxy Protocol draft-jeong-eman-network-proxy-protocol-00.txt Abstract Climate change and cost drives all sectors of industry and society as a whole towards more energy-efficient technology, products and life styles. The collection of Internet infrastructure and the attached devices are a large user of electrical energy and therefore of course are no exception regarding this trend. This memo attempts to identify obstacles and more importantly technology options for an energy-efficient Internet with a focus on the protocols that are the product of the IETF. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on August 22, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must Jeong Expires August 22, 2013 [Page 1] Internet-Draft Network Proxy February 2013 include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 5 3. Overview of Network Proxy . . . . . . . . . . . . . . . . . . 6 4. Network Proxy Operation . . . . . . . . . . . . . . . . . . . 9 5. Message Formats . . . . . . . . . . . . . . . . . . . . . . . 12 6. Security Considerations . . . . . . . . . . . . . . . . . . . 17 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19 8.1. Normative References . . . . . . . . . . . . . . . . . . . 19 8.2. Informative References . . . . . . . . . . . . . . . . . . 19 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 20 Jeong Expires August 22, 2013 [Page 2] Internet-Draft Network Proxy February 2013 1. Introduction ICT sector is facing rapid growth and consuming a lot of power in order to provide large bandwidth and complex application services. According to ITU-T report, wired and wireless networks consume large volume of power for contents delivery. Also the volume of CO2 emissions caused by ICT sector is estimated 2% of total man-made emissions. It is also estimated that network sector contributes to 4% of world power consumption. Also, the ITU-T report has analyzed that almost 50% of power is used due to the operation of networks including wireless and wired networks. Further, the power consumption due to the operation of clouds and data centers shows approximately 23% of total power consumption. Therefore, it is observed that the power consumption is higher at the access part of the network and the operation of data centers, and how to reduce the power consumption in these areas is becoming an important issue [ITU]. According to recent surveys, many network equipments show a constant power consumption profile irrespective of their utilization level, i.e., energy-agnostic power profile. Such equipments represent the worst case in terms of utilization and power consumption profile. On the contrary, ideally, energy-aware equipments represent power consumption pattern proportional to their utilization or offered load. Practical approaches for realizing the energy-aware equipments are implementing multi-stepped power profiles in order to adapt to the utilization level [EPC][GreenSurvey] [EEE]. There is another researh drection for improving energy efficiency of network equipmnet using network proxy technology [I-D.winter-energy-efficient-internet][PROXZZZY] [NCP]. Network proxy describes technologies that maintain network connectivity for other devices so that these can go into low power sleep modes. This mainly targets the reduction of unnecessary energy waste through edge devices. ISO/IEC JTC 1 has published a proxying document [PROXZZZY]. This specification describes an overall architecture for network proxying and provides capabilities that a proxy may expose to a host. Also, information that must be exchanged between a host and a proxy, and required and optional behavior of a proxy during its operation are described. It is well known that many network hosts are in active state in order to maintain network presence and this behavior hinders hosts from entering energy saving state. Even when a node is idle with no running applications, background traffic is received that needs to be processed which inhibits the node from sleeping. Network proxy is one of the possible solution for resolve this issue. The general framework of network proxy was developed, but the control and Jeong Expires August 22, 2013 [Page 3] Internet-Draft Network Proxy February 2013 communication mechanisms between network hosts and proxies has not been developed. Thus, in order to promote the wider deployment of network proxy mechanism, the control and communication protocol should be specified. This document defines a control protocol for network proxy operation and relevant messages in order to increase energy efficiency of network hosts. Jeong Expires August 22, 2013 [Page 4] Internet-Draft Network Proxy February 2013 2. Conventions and Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Jeong Expires August 22, 2013 [Page 5] Internet-Draft Network Proxy February 2013 3. Overview of Network Proxy Network proxy refers to a set of mechanisms dedicated to put network interfaces and networked nodes into energy saving idle mode. Energy consumption in idle mode is less than active mode in general, so the longer the idle periods is, the higher the achievable energy saving can be. Network proxy is a technology that delegates some of networking functions in networked nodes to other network elements such as external nodes or other modules in the nodes. The network proxy enables network nodes to maintain network connectivity during idle mode. Figure 1 shows the typical operational scenario of network proxy. When a host wants to enter energy saving idle mode, the host delivers its network status and state to a network proxy and goes into idle mode. Then, the network proxy responds to periodic messages on behalf of the host in idle mode. If the proxy receives a message that it cannot process, it sends a wake-up message to the host so that the host can process the message after wake-up. Host Proxy Network | | | | | Full Network Connectivity | |<-------------------------------------->| | | Entering| | | Sleep | Context Exchange | | Mode |<------------------>| | | | | In | | | Sleep | |Seletive Net. Conn.| Mode | |<----------------->| . | | | . | | | | | Wake-up Event | | Wake-up |<------------------| |<-------------------| | | | | | Network Connectivity Resumed | Wake-up |<-------------------------------------->| | | Figure 1: Operational scenario of network proxy According to the survey, even though users are idle, background network traffic is nevertheless received and needs processing, preventing thus PCs from going in sleeping mode. Also, it is known that most of the incoming traffic received by a PC network interface during otherwise idle periods can simply be dropped or does not Jeong Expires August 22, 2013 [Page 6] Internet-Draft Network Proxy February 2013 require more than a minimal computation and response. For instance, most broadcast frames or traffic related to port scanning may simply be ignored. Usual exchanges, such as Address Resolution Protocol (ARP) processing, Internet Control Message Protocol (ICMP) echo answering or Dynamic Host Configuration Protocol (DHCP) rebinding, are simple tasks that could be easily performed directly by the network interface. The idea behind network interface proxying consists in delegating the processing of such traffic. Processing can imply plain filtering or may require simple responses (e.g., in the case of ARP, ICMP, DHCP), or even more complex task. Such tasks can be delegated from the CPUs of end devices to a number of different elements either local elements such as low-energy processor onboard of the Network Interface Card (NIC) of the same device, or to an external element in a LAN environment [GreenSurvey]. NIC proxy implements light processing function of the received packets in the NIC. The NIC may drop the periodic protocol message exchange and handle the traffic requiring minimal computation, while the full system will be woken up only when non-trivial packets needing further processing are received. The NIC proxy allows energy saving through power down the end hosts without losing their network connectivity. According to [GreenSurvey], the NIC proxy technique may be applied to more than 90% of the received packets on a host during idle periods. External proxy is offloading traffic processing to an external system within a LAN, so that the proxy acts for a number of end-devices. It can feature a more efficient CPU and thus offload the end-host from an even higher number of network maintenance tasks. Delegation of ARP processing is a typical example of external proxy. For example, a switch acts as a proxy for ARP traffic, allowing the target machine to sleep at least until data traffic is sent. Energy-aware proxies are instead implemented in [SKILL] as a modular routers. The authors implemented four different kinds of proxies, of increasing complexity, showing that, although the potential energy saving is considerable, nevertheless trivial approaches are not sufficient to fully exploit the potential saving. Indeed, while broadcast traffic is easily filtered, a significant implementation effort is needed to properly handle unicast traffic. Finally, it is noted that all the above work do not take into account the residential environment, where set-top-boxes are likely to offer opportunities for external proxy functionality [GreenSurvey]. Regarding the standardization activities for network proxy, ISO/IEC has published ISO/IEC 16317:2011 that specifies maintenance of network connectivity and presence by proxies to extend the sleep duration of hosts. It specifies capabilities that a proxy may expose to a host, information that must be exchanged between a host and a Jeong Expires August 22, 2013 [Page 7] Internet-Draft Network Proxy February 2013 proxy, and required and optional behavior of a proxy while it is operating, including responding to packets, generating packets, ignoring packets, and waking the host. However, the standard does not specify communication mechanisms between hosts and proxies and extension or modification of the referenced specifications, and support of security and communication protocols such as IPsec, MACSec, SSL, TLS, Mobile IP, etc [PROXZZZY]. Therefore, in order to promote the wider deployment of network proxy mechanism, the control and communication protocol should be specified. Jeong Expires August 22, 2013 [Page 8] Internet-Draft Network Proxy February 2013 4. Network Proxy Operation This section describes network proxy operation between proxy server and network nodes. Figure 2 shows network proxy operations. When a network node wants to enter sleep mode in order to save energy, the node exchanges Proxy Solicitation and Advertisement messages with proxy server in network. Proxy server can be implemented as a function within a switch or router, or it may be implemented as a separate server. Proxy Solicitation message queries to network, whether network proxy functionality can be supported within the node!_s network. If there is a network proxy server that can provide proxy functionality, it replies to the node by using Proxy Advertisement message. Jeong Expires August 22, 2013 [Page 9] Internet-Draft Network Proxy February 2013 Sleeping Proxy Remote Host Host | | | | Proxy Solicitation | | |------------------->| | | Proxy Advertisement| | |<-------------------| | | Full Network Connectivity | |<-------------------------------------->| | Sleep Request | | |------------------->| | | Sleep Confirm | | |<-------------------| | | | ARP Request for | | | Other Hosts | | ++ |<------------------| | Ignore+ | . | | ++ |<------------------| ==|====================|===================|== + | | ARP Request for | + + | | Sleeping Host | + Case1 + | Wake-up Packet |<------------------| + + |<-------------------| ARP Reply for | + + | | Sleeping Host | + + | |------------------>| + ==|====================|===================|=+ ==|====================|===================|=+ + | Wake-up Report | | + Case2 + |------------------->| | + + | Wake-up Confirm | | + + |<-------------------| | + +=|====================|===================|=+ | Full Network Connectivity | |<-------------------------------------->| | | Figure 2: Network proxy operation After the proxy server discovery procedure, the node sends ICMP Sleep request message to Proxy Server. The Request message contains the node!_s MAC address(es) and IP address(es). After receiving the Sleep Confirm message from the Proxy Server, the node enters sleep mode. Then the Proxy Server discards ARP Request messages sent from other hosts in the network. By doing so, the node can sleep without receiving or processing ARP broadcast message not destined to the node itself. If the Proxy Server receives an ARP request message for sleeping node, it sends a Wake-up packet to the sleeping node in order to wake it up. During its wake-up process, Proxy Server sends Jeong Expires August 22, 2013 [Page 10] Internet-Draft Network Proxy February 2013 an ARP Reply message for sleeping node. After the sleeping node wakes up, it can communicate with remote hosts. When Sleep Timer expires, the sleeping node wakes up and sends an ICMP Wake-up report message to the Proxy Server. Then, the Proxy Server cleans up the state information for the sleeping node and replies with Wake-up confirm message. Note that Figure 2 shows network proxy operation for processing APR messages and operation for other mandatory protocols specified in [PROXZZZY] will be defined later version of this document. Jeong Expires August 22, 2013 [Page 11] Internet-Draft Network Proxy February 2013 5. Message Formats Figure 3 depicts two types of new ICMP messages for Proxy Request/ Reply messages. The messages are defiend as follows. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Code | Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Message Sub-Type | Transaction ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options (variable size) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Proxy request message Type (Proxy Request) (Proxy Reply) Code 0 Success 1 Fail Checksum The 16-bit one's complement of the one's complement sum of the ICMP message, starting with the ICMP Type. Message Sub-Type 1 Proxy Solicitation Message 2 Proxy Advertisement Message 3 Sleep Request Message 4 Sleep Confirm Message 5 Wake-up Report Message 6 Wake-up Confirm Message Transaction ID Unique identifier created each time a host starts proxy operation Options Optional data for Sub-Type messages Figure 4 shows the Option format for Sub-Type messages. The Option format is defined as a TLV format. Jeong Expires August 22, 2013 [Page 12] Internet-Draft Network Proxy February 2013 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | Data ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Figure 4: Option format Type Indicates the particular sub-type option. 1 Proxy Solicitation Option 2 Proxy Advertisement Option 3 Sleep Request Option 4 Sleep Confirm Option 5 Wake-up Report Option 6 Wake-up Confirm Option Length Indicates the length (in bytes) of the data field within this option. The length does not include the Type and Length bytes. Data The particular data associated with this option. This field may be zero or more bytes in length. The format and length of the data field is determined by the type and length fields. Figure 5 depicts Option format of Proxy Solicitation Sub-Type message. The sub-type message is broadcasted in order to discover proxy in networks. It contains 2 bytes Identifier and 2 bytes sequence number. Currently the detail of Identifier has not been developed, but its format and allocation method will be determined later. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: Proxy solicitation option Figure 6 shows Option format for Proxy Advertisement Sub-Type message used for notifying the Proxy Server!_s presence in network. It is periodically broadcasted to networks and unicasted to a network node Jeong Expires August 22, 2013 [Page 13] Internet-Draft Network Proxy February 2013 that sent a Proxy Solicitation message. The Advertisement message contains the address of Proxy Server!_s IP address(es) and Preference(s). 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Num. of Addr |Addr Entry Size| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Lifetime | Proxy Address 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Proxy Address 1 | Address Preference 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address Preference 1 | Proxy Address 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Proxy Address 2 | Address Preference 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address Preference 2 | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6: Proxy advertisement option Figure 7 shows Optoin format for Sleep Request Sub-Type message. The message is unicasted to Proxy Server and it informs the client!_s entering to sleep mode. Hardware Address Type indicates hardware address type of client. Protocol Type contains protocol address type. H/W length means the length of hardware address. Finally, number of addresses indicates the number of hardware and protocol pairs. Jeong Expires August 22, 2013 [Page 14] Internet-Draft Network Proxy February 2013 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Hardware Address Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Protocol Type | H/W Length | Protocol Len. | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Number of Address | Sender Hardware Address 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sender Hardware Address 1 | Sender Protocol Address 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sender Protocol Address 1 | Sender Hardware Address 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sender Hardware Address 2 | Sender Protocol Address 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sender Protocol Address 2 | ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 7: Sleep request option Figure 8 describes Option format for Sleep Confirm Sub-Type message that is sent from a Proxy Server to Client as a response of Sleep Request message. Code indicates the result of Sleep Request operation. 0 indicates success and 1 indicates failure. Client Identifier is a unique ID for identifying Client and will be allocated by Proxy Server. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Client Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | All zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8: Sleep confirm option Figure 9 depicts Option format for Wake-up report message. It is sent by a client to Proxy Server in order to notify the wake-up event of the client. It is unicasted to the Proxy Server. Client Identifier is the same Identifier assigned by Sleep Confirm message. Jeong Expires August 22, 2013 [Page 15] Internet-Draft Network Proxy February 2013 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Client Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | All zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 9: Wake-up report option Figure 10 shows Option format for Wake-up Confirm message. It is unicasted to a Client as a reply of the Client!_s Wake-up Report message. Code 0 means success and 1 means failure. Client Identifier is the same Identifier assigned by Sleep Confirm message. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Client Identifier | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | All zero | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 10: Wake-up confirm option Jeong Expires August 22, 2013 [Page 16] Internet-Draft Network Proxy February 2013 6. Security Considerations [TBD] Jeong Expires August 22, 2013 [Page 17] Internet-Draft Network Proxy February 2013 7. IANA Considerations [TBD] Jeong Expires August 22, 2013 [Page 18] Internet-Draft Network Proxy February 2013 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 8.2. Informative References [EEE] "802.3az-2010", IEEE std , 2010. [EPC] Barroso, L. and U. Holzle, "The Case for Energy- Proportional Computing", Proc. IEEE International Conference on Network Protocols (ICNP) , December 2007. [GreenSurvey] Bianzino, A., Chaudet, C., Rossi, D., and J. Rougier, "A survey of green networking research", IEEE Communications Surveys Tutorials , 2012. [I-D.winter-energy-efficient-internet] Winter, R., Jeong, S., and J. Choi, "Towards an Energy- Efficient Internet", draft-winter-energy-efficient-internet-01 (work in progress), October 2012. [ITU] "Resolution 73 - Information and communication technologies and climate change", October 2008. [NCP] Jimeno, M., Christensen, K., and B. Nordman, "A Network Connection Proxy to Enable Hosts to Sleep and Save Energy", Proc. IEEE Internat. Performance Computing and Communications Conf , 2008. [PROXZZZY] "ProxZZZy for sleeping hosts", ISO/IEC JTC 1 ISO/IEC 16317, February 2011. [SKILL] Nedevschi, S., Liu, J., Nordman, B., Ratnasamy, S., and N. Taft, "Skilled in the Art of Being Idle: Reducing Energy Waste in Networked Systems", Proc. USENIX Symposium on Networked Systems Design and Implementation , 2009. Jeong Expires August 22, 2013 [Page 19] Internet-Draft Network Proxy February 2013 Author's Address Sangjin Jeong ETRI 218 Gajeongno, Yuseong Daejeon, 305-700 Korea Phone: +82 42 860 1877 Email: sjjeong@etri.re.kr Jeong Expires August 22, 2013 [Page 20]