Flow high availability through PCP
draft-vinapamula-flow-ha-01

Network Working Group                                      S. Vinapamula
Internet-Draft                                          Juniper Networks
Intended status: Standards Track                            S. Sivakumar
Expires: December 15, 2014                                 Cisco Systems
                                                           June 13, 2014

                   Flow high availability through PCP
                      draft-vinapamula-flow-ha-01

Abstract

   This document describes a mechanism for a host to signal various
   network functions' High Availability (HA) module to checkpoint
   interested connections through PCP.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Issues with the existing implementations  . . . . . . . . . .   2
   4.  Proposed Solution . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Some Usage Examples . . . . . . . . . . . . . . . . . . . . .   4
   6.  Signaling HA for other network function . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   9.  Normative references  . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Internet service continuity is critical in service provider
   environment.  To achieve this, most service providers have active-
   backup systems.

   For some of the network functions, a state would be maintained for
   every connection for processing subsequent packets of that
   connection.  For service continuity of those connections on backup
   when active fail, that corresponding state had to be checkpointed on
   the backup.

   NAPT is one such network function, where a state is maintained for
   every connection.

   This document describes some of the existing issues in the way
   checkpointing is done today, and tries to address them.

2.  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.  Issues with the existing implementations

   In a high availability (HA) deployment, it is expensive in terms of
   memory, CPU and other resources to checkpoint all connections state.
   Also checkpointing may not be required for all connections as all
   connections may not be critical.  But, this leaves a challenge to
   identify what connections to checkpoint.

   Typically, this is addressed by identifying long lived connections
   and checkpointing state of only those connections that lived long
   enough, to the backup for service continuity.

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   However, following are the issues with that approach:

   1.  A connection which could potentially be long-lived would face
       disruption in service on failure of active system, before it had
       not lived long enough for it to be checkpointed.

   2.  A connection may not be long lived but critical like shorter
       phone conversations.

   3.  Similarly not every long lived connection need to be critical,
       say a free-service connection of a hosted service need not be
       checkpointed while a paid-service connection has to be
       checkpointed.

4.  Proposed Solution

   This proposal is based on the assumption that an application or user
   is the best judge to decide which of its connections' are critical.

   An application or user MUST indicate that one or more of its
   connections is critical and disruption is not desired.  This will
   trigger checkpointing of state to the backup.

   An application/user may indicate the desire for checkpoint through
   PCP client, and PCP client MUST mark bit zero of "Reserved" bits in
   the PCP request header as below.  Here after in the document, this
   bit is referred as HA bit.

   All other bits in the "Reserved" field MUST be marked zero on
   transmissions and MUST be ignored on reception.

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       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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |  Version = 2  |R|   Opcode    |         Reserved             1|
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                 Requested Lifetime (32 bits)                  |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                                                               |
       |            PCP Client's IP Address (128 bits)                 |
       |                                                               |
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       :                                                               :
       :             (optional) Opcode-specific information            :
       :                                                               :
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       :                                                               :
       :             (optional) PCP Options                            :
       :                                                               :
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   PCP request header with HA bit being the zero bit in the "Reserved"
   field.

   PCP server MAY honor this request depending on whether resources are
   available for checkpointing.  If there are no resources available for
   checkpointing, but there are resources available to honor request say
   PCP MAP/PEER request, request is honored and there is no error
   returned.

   What information to checkpoint and how to checkpoint is out of scope
   of this document, and is left for implementation.

   It is RECOMMENDED to checkpoint state on backup for honored requests
   before a response is sent to the PCP client.

   Communication between application/user and PCP client is
   implementation specific.

5.  Some Usage Examples

   1.  Disruption in a phone connection is not desired.  Application
       that is initiating a phone connection MUST mark connection HA bit
       in the header, while initiating a PCP request for checkpointing.

   2.  Similarly disruption in media streaming is not desired.  A user
       hosting a media service, MUST mark HA bit in the header while
       initiating a mapping request, and MAY mark connection associated

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       with that mapping, depending on whether the connection is from a
       paid subscriber or from a free subscriber through a PEER request.
       So checkpointing mapping doesn't result in auto checkpointing of
       connections, as it gives flexibility to the end user to pick
       specific connections only to checkpoint.

6.  Signaling HA for other network function

   In conjunction with NAT, other network functions that MAY maintain
   state for each conneciton such as Stateful Firewall, IPSec, Load
   balancing etc..., MAY register to PCP server, and MAY be triggered
   for checkpointing respective state of that connection.

7.  Security Considerations

   A network function device can always override the end user signalling
   if the administrator specified rules are not in policy with the end
   user signaling.

   There is a risk that every client may wish to checkpoint every
   connection, which can potentially load the system.  Admin may
   restrict number of connections and the rate of checkpointing on per
   PCP client.

8.  IANA Considerations

   This document does not require any action from IANA.

9.  Normative references

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6887]  Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
              Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
              2013.

Authors' Addresses

   Suresh Vinapamula
   Juniper Networks
   1194 North Mathilda Avenue
   Sunnyvale, CA  94089
   USA

   Phone: +1 408 936 5441
   EMail: sureshk@juniper.net

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   Senthil Sivakumar
   Cisco Systems
   7100-8 Kit Creek Road
   Research Triangle Park, NC  27760
   USA

   Phone: +1 919 392 5158
   EMail: ssenthil@cisco.com

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