Network Working Group Srinivasa Nalluri Internet Draft Ericsson Intended status: Informational May 15, 2015 Expires: August 03, 2015 PPPoE-Bulk-Session Tag extension to PPPoE PADT message draft-snalluri-pppoe-bulk-session-tag-01 Abstract This draft introduces a new PPPoE Tag to PADT message to carry multiple PPPoE session information to BRAS. New tag is intended to reduce processing load on Access Node and BRAS in abnormal network conditions. Status of This Memo 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 theydescribe your rights and restrictions with respect to this document. Code Components extracted from this document must include implified 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. 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 03, 2015. Copyright Notice Copyright (c) 2014 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 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. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Table of Contents 1. Terminology 2. Introduction 3. PPPoE discover phase 4. PPPoE termination stage 5. PPPoE-Bulk-Session Tag format 5.1. TAG_TYPE 5.2. TAG_LENGTH 5.3. TAG_VALUE definition 5.3.1. SESSION_COUNT 5.3.2. RESERVED 5.3.3. SESSION ID list 6. Access Node implementation considerations 7. BRAS implementation considerations 8. IANA considerations 9. Security considerations10.Acknowledgements11.References 11.1 Informative References 11.2 Normative References 1. 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 [3]. ATM - Asynchronous Transfer Mode PPP - Point-to-Point Protocol PPPoA - PPP over AAL5. PPPoE - PPP over Ethernet. MTU - Maximum Transmit Unit PC - Personal Computer. CPE - Customer Premises Equipment RG - Residential Gateway BRAS - Broadband Remote Access Server DSLAM - Digital Subscriber Line Access Multiplexer PPPoE client - PC, RG or CPE which initiates a PPPoE session PPPoE server - BRAS terminating PPPoE sessions initiated by client 2. Introduction In the network designs shown in Figure 1 and Figure 2, which are studied by the Broadband-Forum in the context of the migration to Ethernet for broadband aggregation networks, there exist some scenarios in which PPP clients cannot terminate session as defined in RFC 2516 or in RFC 1661.As studied by Broadband-Forum when LOS is detected on DSL or PON line, Access Node considers that PPP client is not reachable and sends a PADT message to BRAS so that BRAS can clean session as in normal session teardown scenario. In network design shown in Figure 1, when RG sends LCP configure request, Access node generates PPPoE PADI message towards BRAS with self MAC address as source MAC address. In network design shown in Figure 2, when RG sends PPPoE PADI message, Access Node replaces source MAC address in Ethernet header with self MAC address and forwards towards BRAS. In Both cases mentioned above BRAS receives PADI message with source MAC address as Access Node MAC address. Thus BRAS allows multiple PPPoE session for same MAC address. This draft leverages the idea of establishing multiple PPPoE sessions with same MAC address to optimize session teardown scenarios. <----- IPoE -----> <---- PPPoA ----> <- PPPoE session -> +------+ +-----+ +--+ +---+ | | | | |PC|--------------| RG|------------|Access|------------| BRAS| +--+ +---+ | Node | | | +------+ +-----+ Figure 1. Broadband network design with PPPoA to PPPoE conversion <----- IPoE -----> <---- PPPoE ----> <-- PPPoE session --> +------+ +-----+ +--+ +---+ | | | | |PC|--------------| RG|------------|Access|------------|BRAS | +--+ +---+ | Node | | | +------+ +-----+ Figure 2. Broadband network design with DSLAM as PPPoE intermediate agent When LOS observed on multiple access lines, Access node sends one PADT message for each PPP client that is not reachable. In specific scenarios like Access node component crash, geographical power failures or subtended access node failure the scale of PADT messages sent by access node towards BRAS is very high. High number of PADT messages results in high processing load on both Access node and BRAS.This draft introduces a new PPPoE Tag to PADT message to carry multiple PPPoE session information to BRAS. 3. PPPoE discover phase Introduction of this draft does not impact PPPoE discovery phase defined in RFC 2516. 4. PPPoE termination stage If Access Node wants to use bulk PPPoE session teardown capability then it MUST include an optional PPPoE-Bulk-Session tag in PADT message generated towards BRAS. Tag-name: PPPoE-Bulk-Session Tag Type: 0x0122 Tag-Length: Dynamic value as calculated Tag-Value: Binary encoded value as defined in Section 5.3 5. PPPoE-Bulk-Session Tag format 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TAG_TYPE | TAG_LENGTH | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TAG_VALUE ...... ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 5.1. TAG_TYPE Tag Type 0x0122 SHOULD be registered with IANA 5.2. TAG_LENGTH Total length of PPPoE-Bulk-Session tag in octets 5.3. TAG_VALUE definition 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SESSION_COUNT | RESERVED | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SESSION ID_1 | SESSION_ID 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SESSION_ID 3 | SESSION_ID 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | .......... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | .......... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SESSION_ID N-1 | SESSION_ID N | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 5.3.1. SESSION_COUNT Number of Session records encoded in TAG_VALUE. This value depends on MTU supported between Access Node and BRAS. In order to make sure PADT message is transmitted between Access Node and BRAS implementations MUST consider MTU values. 5.3.2. RESERVED Three octets field reserved for future use and MUST be filled with zero. 5.3.3. SESSION ID list List of PPPoE Session IDs served by PPPoE server during PPPoE session discover phase. 6. Access Node implementation considerations Destination MAC address in PADT message Ethernet header SHOULD be PPPoE server MAC address. Source MAC address in PADT message Ethernet header MUST be same as source MAC address used during PPPoE session discover phase. Access node MUST NOT bundle PPPoE session IDs mapped to different source MAC addresses in one PADT message. PPPoE Session ID MUST in PADT message with PPPoE Bulk Session Tag MUST be 0xFFFE. In order to maintain backward compatibility, Access node MUST be capable of generating PADT message as defined in RFC 2516. Access node MUST consider operator configuration as selection criteria between legacy and new PADT formats. 7. BRAS implementation considerations BRAS or PPPoE server that can handle PPPoE-Bulk-session tag MUST handle PADT messages with PPPoE session ID 0xFFFE and tag type 0x0122. When received such message, BRAS should perform following. - Extract Ethernet source MAC address from Ethernet header that is SOURCE_ADDR. - Extract Ethernet destination MAC address from Ethernet header that is DESTINATION_ADDR. - For each session ID in tag value, identify PPPoE session uniquely by {session ID, SOURCE_ADDR, DESTINATION_ADDR} and clean the session. PPPoE server that cannot support PPPoE-Bulk-Session tag SHOULD ignore and silently drop any PADT message with PPPoE-Bulk-Session tag. In order to maintain backward compatibility BRAS MUST support processing of PADT message format as defined in RFC 2516. 8. IANA considerations IANA considerations required to register new PPPoE Tag type as follows TAG Value TAG Name ---- ------ --------- 290 0x0122 PPPoE_Bulk_Session 9. Security considerations This document introduces no new security threat 10. Acknowledgements This document is based on concepts described in several forums, including Broad Band forum and IETF. Many thanks to David Allan I, Natarajan Venkataraman, Narayana Pai and Suresh Gangadharan for useful inputs and feedback. 11. References 11.1 Informative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 11.2 Normative References [2]. Mamakos L., Lidl K., Evarts J., Carrel D., Simone D., Wheeler R., "A Method for Transmitting PPP Over Ethernet (PPPoE)", RFC 2516, February 1999 [3]. W. Simpson "The Point-to-Point Protocol (PPP)", RFC 1661, July 1994 Author's Addresses Srinivasa Rao Nalluri Ericsson Level-5 Ferns Icon, Outer Ring Road, Doddanakundi Marathahalli, Bangalore India-560037 Email: srinivasa.rao.nalluri@ericsson.com