OSPF extension for priority allocation support in the PCE discovery
draft-wu-pce-discovery-priority-allocation-00

Abstract

Each network domain may contain multiple PCE servers. It provides redundancy to the PCCs in the event of a server failure. However load balance decision is made by PCC,it doesn’t enable real load balance across the PCE servers if PCC still tries PCE one by one and PCE doesn’t indicate the load status to the PCC.

This document proposes new PCE discovery sub-TLV that can be announced as attribute in the OSPF advertisement (defined in [RFC5088 ]) to distribute priority information.

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 January 16, 2014.

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 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
• 2. Conventions used in this document
• 3. PCE-ALLOCATION-PRIORITY Sub-TLV for PCE Load Balancing
• 3.1. Use of PCE-ALLOCATION-PRIORITY sub-TLV for PCE discovery
• 4. Security Considerations
• 5. IANA Considerations
• 6. Normative References
• Author's Address

1. Introduction

Usually a single PCE server sits per domain in the nework. The PCE server disseminates its address in the network using OSPF [RFC5088] or ISIS [RFC5089] and the PCCs connect to it automatically. However in some cases, each network domain may contain multiple PCE servers. It provides redundancy to the PCCs in the event of a server failure.

However load balance decision is made by PCC,it doesn’t enable real load balance across the PCE servers if PCC still tries PCE one by one and PCE doesn’t indicate the load status to the PCC (e.g., the number of incoming requests that have already targeted to the PCE).

This document proposes new PCE discovery TLV that can be announced as attribute in the OSPF advertisement (defined in [RFC5088 ]) to distribute priority information.

2. Conventions used in this document

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 [RFC2119].

3. PCE-ALLOCATION-PRIORITY Sub-TLV for PCE Load Balancing

The PCE-Allocated-Priority sub-TLV is an optional sub-TLV used to indicate allocated priority of each PCE. The format of the sub-TLVs is identical to the TLV format used by the Traffic Engineering Extensions to OSPF [RFC3630]. It MAY be present within the PCED TLV. It MUST NOT be present more than once. If it appears more than once, only the first occurrence is processed and any others MUST be ignored.

The value field of the PCE-ALLOCATED-PRIORITY sub-TLV is expressed as 32-bit unsigned integer value..

The format of the PCE-ALLOCATED-PRIORITY sub-TLV is 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 = TBD         |            Length           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    Allocated Priority                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Type:     TBD
      Length:   4 octets
      Value:    This contains allocated priority value for each PCE 
                server. The priority value can be allocated based 
                on PCE load or incoming request to the PCE server.

3.1. Use of PCE-ALLOCATION-PRIORITY sub-TLV for PCE discovery

Multiple servers can be present in a single network for redundancy in which case each PCE server is allocated with a priority value. The priority can be allocated based on PCE load (e.g., incoming request to the PCE server) announced as attribute in the OSPF advertisement. The PCC can be configured to use the highest priority PCE server that is available or specify the priority of a computation request when multiple PCEs has already been found using OSPF[RFC5088].

4. Security Considerations

This document raises no new security issues beyond those described in [RFC5088].

5. IANA Considerations

IANA maintains the registry for the TLVs. PCE-allocated-priority sub-TLV will require one new type code per sub-TLV defined in this document.

6. Normative References

Author's Address