IPFIX Working Group A. Johnson Internet-Draft B. Claise Intended status: Standards Track P. Aitken Expires: October 9, 2011 Cisco System, Inc. J. Schoenwaelder Jacobs University Bremen April 7, 2011 Exporting MIB Variables using the IPFIX Protocol draft-johnson-ipfix-mib-variable-export-01 Abstract This document specifies a way to complement IPFIX Flow Records with Management Base (MIB) objects, avoiding the need to define new IPFIX Information Elements for existing Management Information Base objects that are already fully specified. This method requires an extension to the current IPFIX protocol. New Template Set and Options Template Sets are specified to allow the export of Simple Network Management Protocol (SNMP) MIB Objects along with IPFIX Information Elements. 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 October 9, 2011. Copyright Notice Copyright (c) 2011 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 Johnson, et al. Expires October 9, 2011 [Page 1] Internet-Draft Exporting MIB Variables with IPFIX April 2011 (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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Motivation and Architectural Model . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. MIB OID Extended Template Formats . . . . . . . . . . . . . . 6 4.1. MIB OID Extended Template Record Format . . . . . . . . . 6 4.2. MIB OID Extended Options Template Record Format . . . . . 7 4.3. MIB OID Extended Field Specifier Format . . . . . . . . . 8 4.3.1. Standard Field Specifier Format . . . . . . . . . . . 8 4.3.2. Extended Field Specifier Format for non-indexed MIB Object . . . . . . . . . . . . . . . . . . . . . . 9 4.3.3. Extended Field Specifier Format for Indexed MIB Object . . . . . . . . . . . . . . . . . . . . . . . . 11 4.4. Identifying the SNMP Context . . . . . . . . . . . . . . . 15 4.5. Template Management . . . . . . . . . . . . . . . . . . . 15 5. Example Use Cases . . . . . . . . . . . . . . . . . . . . . . 15 5.1. Non-indexed MIB Object: Detailing CPU Load History . . . . 15 5.2. Indexed MIB Objects: Output Interface Queue Size in PSAMP Packet Report . . . . . . . . . . . . . . . . . . . 18 5.3. Indexed MIB Objects with an OID as indexed: ... . . . . . 21 6. Configuration Considerations . . . . . . . . . . . . . . . . . 22 7. The Collecting Process's Side . . . . . . . . . . . . . . . . 22 8. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 22 9. Security Considerations . . . . . . . . . . . . . . . . . . . 23 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 11.1. Normative References . . . . . . . . . . . . . . . . . . . 23 11.2. Informative References . . . . . . . . . . . . . . . . . . 24 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 24 Johnson, et al. Expires October 9, 2011 [Page 2] Internet-Draft Exporting MIB Variables with IPFIX April 2011 1. Introduction There is growing interest in using IPFIX as a push mechanism for exporting management information. Using a push protocol such as IPFIX instead of a polling protocol like SNMP is especially interesting in situations, where large chunks of repetitive data need to be exported periodically. While initially targeted at different problems, there is a large parallel between the information transported via IPFIX and SNMP. Furthermore, certain Management Information Base (MIB) objects are highly relevant to flows as they are understood today. For example, in the IPFIX information model [RFC5102], Information Elements coming from the SNMP world have already been specified, e.g., ingressInterface and egressInterface both refer to the ifIndex defined in [RFC2863]. Rather than mapping existing MIB objects to IPFIX Information Elements on a case by case basis, it would be advantageous to enable the export of any existing or future MIB objects as part of an IPFIX Flow Record. This way, the duplication of data models [RFC3444], both as SMI MIB objects and IPFIX Information Elements, out of the same information model [RFC3444] would be avoided. In this document, new Template Sets for Flow Records and Options Records are specified to allow Templates to contain any combination of fields defined by traditional IPFIX Information Elements and/or MIB Object Identifiers. The MIB Object Identifiers can reference either non-indexed or indexed MIB objects. When an indexed MIB object is exported, a method to identify how that MIB object was indexed is specified so that the full meaning of the information being exported can be conveyed. A set of example use cases is used to illustrate how these specifications can be used. 2. Motivation and Architectural Model Most Flow Records contain the ingressInterface and/or the egressInterface Information Element. These Information Elements carry an ifIndex value, a MIB object defined in [RFC2863]. In order to retrieve additional information about the identified interface, a Collector could simply poll relevant objects from the device running the Exporter via SNMP. However, approach has several problems: o It requires implementing a mediation function between two data models, i.e., MIB objects and IPFIX Information Elements. Johnson, et al. Expires October 9, 2011 [Page 3] Internet-Draft Exporting MIB Variables with IPFIX April 2011 o Confirming the validity of simple mappings (e.g., ifIndex to ifName) requires to either check on a regular basis that the Exporter's network management system did not reload, or to impose ifIndex persistence across an Exporter's reload. o Synchronization problems occur since counters carried in Flow Records and counters carried in SNMP messages are retrieved from the Exporter at different points in time amd thus can't be correlated. In the best case, assuming very tight integration of an IPFIX Collector with and SNMP polling engine, SNMP data is retrieved shortly after Data Records have been received, which implies the sum of the active or inactive timeouts (if not null) plus the time to export the Flow Record to the Collector. If, however, the SNMP data is retrieved by a generic Network Management Station (NMS) polling interface statistics, then the time lag between IPFIX counters and SNMP counters can be significant. The intended scope of this work is the addition of MIB variable(s) to IPFIX Information Elements in Flow Records, in order to complement the Flow Records with useful and already standardized information. The intended goal of this work is not a replacement of SNMP notifications, even if the specifications in this document could potentially allow this. Since IPFIX is a push mechanism, initiated from the Exporter with no acknowledgment method, this specification does not provide the ability to execute configuration changes. The Distributed Management Expression MIB [RFC2982], which is a mechanism to create new MIB variables based on the content of existing ones, could also be advantageous in this context of this specification. Indeed, newly created MIB object (for example, the link utilization MIB variable), created with the Distributed Management Expression MIB [RFC2982] could nice complement Flow Records. Another advantage of exporting MIB objects via IPFIX is that IPFIX would benefit from an extended series of types to be exported. The simple and application-wide data types specified in SMIv2 [RFC2578], along with a new textual conventions, can be exported within IPFIX and then decoded in the Collector. Johnson, et al. Expires October 9, 2011 [Page 4] Internet-Draft Exporting MIB Variables with IPFIX April 2011 +------+ +-------+ +.........+ +.....+ | SNMP | | IPFIX | : NETCONF : : CLI : +------+ +-------+ +.........+ +.....+ | | | | +--------------------------------------------+ | Instrumentation (specified in MIB modules) | +--------------------------------------------+ Figure 1: Architectural Model The overall architectural model is depicted in Figure 1. The IPFIX Exporter accesses the device's instrumentation, which follows the specifications contained in MIB modules. Other management interfaces such as NETCONF or the device's Command Line Interface (CLI) may provide access to the same instrumentation. 3. Terminology IPFIX-specific terminology (Information Element, Template, Template Record, Options Template Record, Template Set, Collector, Exporter, Flow Record, etc.) used in this document is defined in Section 2 of [RFC5101]. As in [RFC5101], these IPFIX-specific terms have the first letter of a word capitalized. This document prefers the more generic term "Data Record" as opposed to "Flow Record" as this specification allows the export of MIB objects. MIB Object Identifier (MIB OID) An ASCII character sequences of decimal non-negative sub- identifier values. Each sub-identifier value MUST NOT exceed 2^32-1 (4294967295) and MUST NOT have leading zeros. Sub- identifiers are separated by single dots and without any intermediate whitespace. MIB Object Identifier Information Element An IPFIX Information Element ("MIBObjectIdentifierMarker") that denotes that a MIB Object Identifier is exported in the (Options) Template Record. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. Johnson, et al. Expires October 9, 2011 [Page 5] Internet-Draft Exporting MIB Variables with IPFIX April 2011 4. MIB OID Extended Template Formats Extended Template Record Formats are required to send data defined by MIB Object Identifiers. New Template Sets are required for these extended Template Record Formats. 4.1. MIB OID Extended Template Record Format The format of the MIB Object Identifier Extended Template Record is shown in Figure 2. It consists of a Template Record Header and one or more Field Specifiers. +---------------------------------------------------+ | Template Record Header | +---------------------------------------------------+ | Field Specifier | +---------------------------------------------------+ | Field Specifier | +---------------------------------------------------+ ... +---------------------------------------------------+ | Field Specifier | +---------------------------------------------------+ Figure 2: MIB Object Identifier Extended Template Record Format A MIB Object Identifier Extended Template Record MUST contain at least one MIB Object Identifier Extended Field Specifier. It MAY also contain any combination of IANA-assigned and/or Enterprise- Specific Information Element identifiers as specified in [RFC5101]. The format of the Template Record Header is shown in Figure 3. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID (> 255) | Field Count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 3: Template Record Header Format Where: Template ID Template ID of this Template Record. This value is greater than 255. Johnson, et al. Expires October 9, 2011 [Page 6] Internet-Draft Exporting MIB Variables with IPFIX April 2011 Field Count Number of all fields in this Template Record. At this level of detail the layout of the Template Record Format, as specified in [RFC5101], and the MIB Object Identifier Extended Template Record Format are identical. It is only the structure of the Field Specifiers that is different (see Section 4.3). 4.2. MIB OID Extended Options Template Record Format The format of the MIB Object Identifier Extended Options Template Record is shown in Figure 4. It consists of an Options Template Record Header and one or more Field Specifiers. +---------------------------------------------------+ | Options Template Record Header | +---------------------------------------------------+ | Field Specifier | +---------------------------------------------------+ | Field Specifier | +---------------------------------------------------+ ... +---------------------------------------------------+ | Field Specifier | +---------------------------------------------------+ Figure 4: MIB Object Identifier Options Extended Template Record Format A MIB Object Identifier Extended Options Template Record MUST contain at least one MIB Object Identifier Extended Field Specifier, which MAY be a scope field. It MAY also contain any combination of IANA- assigned and/or Enterprise-Specific Information Element identifiers. The format of the Options Template Record Header is shown in Figure 5. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID (> 255) | Field Count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Scope Field Count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 5: Options Template Record Header Format Johnson, et al. Expires October 9, 2011 [Page 7] Internet-Draft Exporting MIB Variables with IPFIX April 2011 Where: Template ID Template ID of this Template Record. This value is greater than 255. Field Count Number of all fields in this Template Record, including the Scope Fields. Scope Field Count Number of scope fields in this Options Template Record. The Scope Fields are normal Fields except that they are interpreted as Scope at the Collector. The Scope Field Count MUST NOT be zero for an Options Template Record. As with the Template Record Format, the only difference between the standard Options Template Record Format as defined in [RFC5101] and the MIB Object Identifier Extended Template Options Record Format is the structure of the Field Specifier (see Section 4.3). 4.3. MIB OID Extended Field Specifier Format This section specifies how the Field Specifier format in [RFC5101] is extended to allow fields to be defined using a specified MIB Object. First for a MIB Object Identifier that is a non-indexed MIB object, then for an indexed MIB object. The Field Specifier formats are shown in Figure 6 to Figure 10 below. 4.3.1. Standard Field Specifier Format The Field Specifier format in Figure 6, along with the associated definitions, has been copied from [RFC5101], for an easier comparison with the MIB Object Identifier Extended Field Specifier Format in Figure 7 and Figure 10. When sending an IANA-assigned and/or Enterprise-Specific Information Element identifier, the Field Specifier Format is the same as shown below. Johnson, et al. Expires October 9, 2011 [Page 8] Internet-Draft Exporting MIB Variables with IPFIX April 2011 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| Information Element ident. | Field Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Enterprise Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 6: Standard Field Specifier format Where: E Enterprise bit. This is the first bit of the Field Specifier. If this bit is zero, the Information Element Identifier identifies an IETF specified Information Element, and the four octet Enterprise Number field MUST NOT be present. If this bit is one, the Information Element identifier identifies an enterprise-specific Information Element, and the Enterprise Number filed MUST be present. Information Element identifier A numeric value that represents the type of the Information Element. Refer to [RFC5102]. Field Length The length of the corresponding encoded Information Element, in octets. Refer to [RFC5102]. The field length may be smaller than the definition in [RFC5102] if reduced size encoding is used. The value 65535 is reserved for variable length Information Element. Enterprise Number IANA enterprise number [PEN] of the authority defining the Information Element identifier in this Template Record. 4.3.2. Extended Field Specifier Format for non-indexed MIB Object When a MIB object is to be exported, a special Information Element value is used to show that the extended Field Specifier is being used, as shown in Figure 7: Johnson, et al. Expires October 9, 2011 [Page 9] Internet-Draft Exporting MIB Variables with IPFIX April 2011 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| MIB OID IE | Field Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Index Count = 0|MIB Obj. ID Len| MIB Object Identifier ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 7: MIB Object Identifier Extended Field Specifier Format for a non-indexed MIB Object with an OID length < 255 Where: E Enterprise bit. This is the first bit of the Field Specifier. If this bit is zero, the Information Element Identifier identifies an IETF specified Information Element, and the four octet Enterprise Number field MUST NOT be present. If this bit is one, the Information Element identifier identifies an enterprise-specific Information Element, and the Enterprise Number filed MUST be present. MIB OID IE Special IPFIX Information Element, MIBObjectIdentifierMarker, that denotes that a MIB object is exported in the (Options) Template Record. When the MIB Object Identifier Information Element (MIB OID IE) is used, the MIB Object Identifier must be specified in the Field Specifier for the Collecting Process to be able to decode the Records. Field Length The definition is as [RFC5101]. Index Count The number of indexes for a MIB object, and zero for a non- indexed MIB object. MIB Object Identifier Length The length of the textual representation of the MIB Object Identifier that follows. This is encoded in the same manner as the variable length encoding in [RFC5101]. If the length of Johnson, et al. Expires October 9, 2011 [Page 10] Internet-Draft Exporting MIB Variables with IPFIX April 2011 the MIB Object Identifier is greater than or equal to 255 octets, the length is encoded into 3 octets before the MIB Object Name. The first octet is 255 and the length is carried in the second and third octets (as shown in Figure 8). MIB Object Identifier The textual representation of a MIB object identifier as defined in Section 3. If the MIB Object Identifier is longer than 254 characters then the length MUST be extended. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| MIB OID IE | Field Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Index Count = 0| 255 | MIB Object Identifier Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MIB Object Identifier ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 8: MIB Object Identifier Extended Field Specifier Format for a non-indexed MIB Object with an OID length >= 255 4.3.3. Extended Field Specifier Format for Indexed MIB Object The mechanism for "Extended Field Specifier Format for non-indexed MIB Object" in Section 4.3.2 can be used for exporting any MIB objects, including the indexed MIB objects. However, per the nature of indexing in MIB module, every indexed object is specified by a new MIB Objet Identifier, which in turn implies that a new Template Record must be used for every indexed object. For example, the ifInOctets for the interface represented by the interface ifIndex 1 is ifInOctets.1, the ifInOctets for the interface represented by the interface ifIndex 2 is ifInOctets.2, ... which causes the mechanism for "Extended Field Specifier Format for non-indexed MIB Object" to export indexed MIB objects completely inefficient. When an indexed MIB object is exported in IPFIX, the meaning of the exported value each index SHOULD be identified. This index (or indexes) MAY be an IPFIX Information Element or MIB Object Identifier. Note that the IPFIX Information Element MAY be an enterprise-specific Information Element. In all cases, MIB index information elements MUST be consistent with the MIB definition. Johnson, et al. Expires October 9, 2011 [Page 11] Internet-Draft Exporting MIB Variables with IPFIX April 2011 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| MIB OID IE | Field Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Index Count |MIB Obj. ID Len| MIB Object Identifier ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| Index Information Element 1 |E| Index Information Element 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Enterprise Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Figure 9: MIB Object Identifier Extended Field Specifier Format with an indexed MIB Object using a IPFIX I.E. as Index Where: E Enterprise bit. In the special case of a MIB Object Identifier export, the Enterprise bit MUST always be 0, even if the exported MIB object is specified in a proprietary MIB, therefore containing the private enterprise number in its OID. For any indexes identified using Information Elements the Enterprise bit can be 1, indicating that an Enterprise Number will follow the Information Element. MIB OID IE Special IPFIX Information Element, MIBObjectIdentifierMarker, that denotes that a MIB object is exported in the (Options) Template Record. When the MIB Object Identifier Information Element (MIB OID IE) is used, the MIB Object Identifier must be specified in the Field Specifier for the Collecting Process to be able to decode the Records. Field Length The definition is as [RFC5101]. Index Count The number of indexes for a MIB object, and zero for a non- indexed MIB object. The index count MUST be consistent with the INDEX definition of the corresponding MIB module. Johnson, et al. Expires October 9, 2011 [Page 12] Internet-Draft Exporting MIB Variables with IPFIX April 2011 MIB Object Identifier Length The length of the textual representation of the MIB Object Identifier that follows. This is encoded in the same manner as the variable length encoding in [RFC5101]. If the length of the MIB Object Identifier is greater than or equal to 255 octets, the length is encoded into 3 octets before the MIB Object Name. The first octet is 255 and the length is carried in the second and third octets (as shown in Figure 8). MIB Object Identifier The textual representation of a MIB object identifier as defined in Section 3. A MIB Object Identifier MAY be used as an index and sent as described in Figure 10. If a MIB Object Identifier with an index is used as an index then its indexes will not be identified. 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| MIB OID IE | Field Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Index Count | MIB OID Len 1 | MIB Object Identifier 1 ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier 1 continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| MIB OID IE | MIB OID Len 2 | MIB OID 2 ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier 2 continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Figure 10: MIB Object Identifier Extended Field Specifier Format with a MIB Index using a normal MIB Object Identifier as index Where: E Enterprise bit. In the special case of a MIB Object Identifier export, the Enterprise bit MUST always be 0, even if the exported MIB object is specified in a proprietary MIB, therefore containing the private enterprise number in its OID. For any indexes identified using Information Elements the Enterprise bit can be 1, indicating that an Enterprise Number will follow the Information Element. Johnson, et al. Expires October 9, 2011 [Page 13] Internet-Draft Exporting MIB Variables with IPFIX April 2011 MIB OID IE Special IPFIX Information Element, MIBObjectIdentifierMarker, that denotes that a MIB object is exported in the (Options) Template Record. When the MIB Object Identifier Information Element (MIB OID IE) is used, the MIB Object Identifier must be specified in the Field Specifier for the Collecting Process to be able to decode the Records. Field Length The definition is as [RFC5101]. Index Count The number of indexes for a MIB object, and zero for a non- indexed MIB object. MIB Object Identifier Length 1 The length of the textual representation of the MIB Object Identifier being exported. This is encoded in the same manner as the variable length encoding in [RFC5101]. If the length of the MIB Object Identifier is greater than or equal to 255 octets, the length is encoded into 3 octets before the MIB Object Name. The first octet is 255 and the length is carried in the second and third octets. MIB Object Identifier 1 The textual representation of a MIB object identifier as defined in Section 3. MIB Object Identifier Length 2 The length of the textual representation of the MIB Object Identifier being used as an index. This is encoded in the same manner as the variable length encoding in [RFC5101]. If the length of the MIB Object Identifier is greater than or equal to 255 octets, the length is encoded into 3 octets before the MIB Object Name. The first octet is 255 and the length is carried in the second and third octets. MIB Object Identifier 2 The textual representation of a MIB object identifier as defined in Section 3. Johnson, et al. Expires October 9, 2011 [Page 14] Internet-Draft Exporting MIB Variables with IPFIX April 2011 4.4. Identifying the SNMP Context Each MIB OID is looked up in a specific context, usually the default context. If exporting a MIB OID value that isn't in the default context then the context string MUST be identified and associated with the MIB OID. This can be done on a per template basis by exporting an Options Template Record. A new IPFIX Information Element has been allocated for this purpose... 4.5. Template Management Templates are managed as per [RFC5101]. The Set ID field MUST contain the value TBD1 for any Template Set that contains a MIB Object Identifier Extended Field Specifier. The Template Withdrawal Message for such a Template must also use a Set ID field containing the value TBD1. The Set ID field MUST contain the value TBD2 for any Option Template Set that contains a MIB Object Identifier Extended Field Specifier. The Template Withdrawal Message for such an Option Template must also use a Set ID field containing the value TBD2. 5. Example Use Cases 5.1. Non-indexed MIB Object: Detailing CPU Load History The CPU Usage of a remote network device could be monitored by configuring it to periodically send CPU usage information to a centralized Collector. In this example, the Exporter would send an IPFIX Message every 30 minutes that contained Data Records detailing the CPU 1 minute busy average at 1 minute intervals. The table of data that is to be exported would look like: Johnson, et al. Expires October 9, 2011 [Page 15] Internet-Draft Exporting MIB Variables with IPFIX April 2011 +-------------------------+---------------------+ | TIMESTAMP | CPU BUSY PERCENTAGE | +-------------------------+---------------------+ | StartTime + 0 seconds | 10% | | StartTime + 60 seconds | 14% | | StartTime + 120 seconds | 19% | | StartTime + 180 seconds | 16% | | StartTime + 240 seconds | 23% | | StartTime + 300 seconds | 29% | +-------------------------+---------------------+ Table 1: CPU Usage Data The Template Record for such a Data Record will detail two Information Elements: 1. flowStartSeconds from [RFC5102], Information Element 150: The absolute timestamp of the first packet of this Flow. 2. cpmCPUTotal1minRev from the proprietary CISCO-PROCESS-MIB, Object ID "1.3.6.1.4.1.9.9.109.1.1.1.1.7", The overall CPU busy percentage in the last one-minute period Figure 11 shows the exported Template Set detailing the Template Record for exporting CPU Load (see Section 5.1). Johnson, et al. Expires October 9, 2011 [Page 16] Internet-Draft Exporting MIB Variables with IPFIX April 2011 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = TBD1 | Length = 47 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 256 | Field Count = 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |E| IE = flowStartSeconds | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| MIBObjectIdentiferMarker | Field Length 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Index Count = 0|MIB OID Len=29 | MIB Object Identifier ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | = "1.3.6.1.4.1.9.9.109.1.1.1.1.7" | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MIB Object Identifier continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 11: Example of CPU Load Template Set Figure 12 shows the start of the data set for exporting the CPU Load information (see Section 5.1). Johnson, et al. Expires October 9, 2011 [Page 17] Internet-Draft Exporting MIB Variables with IPFIX April 2011 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = 256 | Length = 256 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | StartTime + 0 seconds | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 10 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | StartTime + 60 seconds | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 14 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | StartTime + 120 seconds | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 19 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | StartTime + 180 seconds | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 16 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ... Figure 12: Example of CPU Load Template Set 5.2. Indexed MIB Objects: Output Interface Queue Size in PSAMP Packet Report If a PSAMP Packet Report [RFC5476] was generated on any dropped packets on an interface then it may be desirable to know if the send queue on the output interface was full. This could be done be sending the size of the send queue (ifOutQLen) in the same Data Record as the PSAMP Packet Report. The exported data would look like: +-----------+-----------+--------+-----------+----------------------+ | SCR ADDR | DST ADDR | PAK | OUTPUT | OUTPUT Q. LEN | | | | LEN | I/F | (ifOutQLen) | +-----------+-----------+--------+-----------+----------------------+ | 192.0.2.1 | 192.0.2.3 | 150 | Eth 1/0 | 45 | | 192.0.2.4 | 192.0.2.9 | 350 | Eth 1/0 | 45 | | 192.0.2.3 | 192.0.2.9 | 650 | Eth 1/0 | 23 | | 192.0.2.4 | 192.0.2.6 | 350 | Eth 1/1 | 0 | +-----------+-----------+--------+-----------+----------------------+ Table 2: Packet Report with Interface Output Queue Length (ifOutQLen) Data Johnson, et al. Expires October 9, 2011 [Page 18] Internet-Draft Exporting MIB Variables with IPFIX April 2011 The MIB object for the Interface Output Queue Length, ifOutQLen ("1.3.6.1.2.1.2.2.1.21"), is indexed by the ifIndex interface index as detailed in the IF-MIB [RFC2863]. If, for example, the interface index of "Eth 1/0" in our example is 15, the full MIB Object Identifier for (ifOutQLen) would be "1.3.6.1.2.1.2.2.1.21.15". Without a method to specify the index the full MIB OID would have to be used, which would mean specifying a new Template Record. Rather than send a separate Template Record for each Interface Index, it would be much more convenient to identify the index in the Data Record itself. In fact, only how the indexed object was indexed is necessary, although it is often useful to specify the index value. In our example we identify the Egress Interface, but for other uses it may be sufficient to know that the ifOutQLen value was taken for the interface that the packet was switched out of, without identifying the actual interface. The Template Record for our example Data Record would contain the following Information Elements: 1. sourceIPv4Address 2. destinationIPv4Address 3. totalLengthIPv4 4. egressInterface 5. ifOutQLen indexed by: egressInterface Figure 13 shows the exported Template Set detailing the Template for exporting a PSAMP Report with Interface Output Queue Length (ifOutQLen) (see Section 5.2). Johnson, et al. Expires October 9, 2011 [Page 19] Internet-Draft Exporting MIB Variables with IPFIX April 2011 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = TBD1 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 257 | Field Count = 5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| IE = sourceIPv4Address | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| IE = destinationIPv4Address | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| IE = totalLengthIPv4 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| IE = egressInterface | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| MIBObjectIdentifierMark | Field Length 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Index Count=1 |MIB OID Len=20 | MIB Object Identifier ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | = "1.3.6.1.2.1.2.2.1.21" | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB OID continued |0| IE = egressInterface | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 13: Example of PSAMP Report with ifOutQLen Figure 14 shows the exported Template Set detailing the Template for exporting a PSAMP Report with Interface Output Queue Length (ifOutQLen) but using the ifIndex MIB object as the exported index, rather than the Egress Interface Information Element. Johnson, et al. Expires October 9, 2011 [Page 20] Internet-Draft Exporting MIB Variables with IPFIX April 2011 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Set ID = TBD1 | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Template ID = 257 | Field Count = 5 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| IE = sourceIPv4Address | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| IE = destinationIPv4Address | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| IE = totalLengthIPv4 | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0| IE = egressInterface | Field Length = 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0|IE=MIBObjectIdentifierMarker | Field Length 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Index Count=1 |MIB OID Len=20 | MIB Object Identifier ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | = "1.3.6.1.2.1.2.2.1.21" | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB OID continued |0|IE=MIBObjectIdentifierMarker | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | MIB Object Identifier = "1.3.6.1.2.1.2.2.1.1" | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued ... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ... MIB Object Identifier continued | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 14: Example of PSAMP Report with ifOutQLen using ifIndex from IF-MIB as an index [RFC2578] 5.3. Indexed MIB Objects with an OID as indexed: ... To be completed Johnson, et al. Expires October 9, 2011 [Page 21] Internet-Draft Exporting MIB Variables with IPFIX April 2011 6. Configuration Considerations When configuring a MIB OID for export, consideration should be given to whether the SNMP Context String should also be configurable. If a non-default Context String is used then it should be associated with the fields as per Section 4.4. 7. The Collecting Process's Side This section describes the Collecting Process when using SCTP and PR- SCTP as the transport protocol. Any necessary changes to the Collecting Process specifically related to TCP or UDP transport protocols are specified in section 10 of RFC 5101. The specifications in section 9 of RFC 5101 also apply to Collector's that implement this specification. In addition, the following specifications should be noted. A Collecting Process that implements this specification MUST be able to receive Set IDs TBD1 and TBD2, as specified in this document. A Collecting Process that implements this specification MUST have access to MIB modules in order to look up the received MIB Object Identifiers and find the type and name of MIB OID fields used in received templates. It should be noted that since reduced length encoding MAY be used by the Exporting Process then the Collecting Process cannot assume a received size for a field is the maximum size it should expect for that field. If a Collecting Process receives a MIB Object ID that it cannot decode, it SHOULD log an error. If a Collecting Process receives a MIB Object ID for an indexed MIB Object but isn't sent the appropriate number of indexes then it SHOULD log an error, but it MAY use the Template Record to decode the Data Records as the associated indexes are purely semantic information. 8. Applicability Making available the many and varied items from MIB modules opens up a wide range of possible applications for the IPFIX protocol, some quite different from the usual flow information. Some potential enhancements for traditional applications are detailed below: Some monitoring applications periodically export an interface id to Johnson, et al. Expires October 9, 2011 [Page 22] Internet-Draft Exporting MIB Variables with IPFIX April 2011 interface name mapping using IPFIX Options Templates. This could be expanded to include the MIB object "ifInUcastPkts" of the IF-MIB [RFC2863] indexed using the ingressInterface Information Element, as a index. This would give the input statistics for each interface which can be compared to the flow information to ensure the sampling rate is expected. Or, if there is no sampling, to ensure that all the expected packets are being monitored. 9. Security Considerations For this extension to the IPFIX protocol, the same security considerations as for the IPFIX protocol apply [RFC5101]. The access to MIB objects is controlled by the configuration of the IPFIX exporter. This is consistent with the way IPFIX controls access to other Information Elements in general. The configuration of an IPFIX exporter determines which MIB objects are included in IPFIX flow records sent to certain collectors. Network operators should take care that only MIB objects are included in IPFIX flow records that the receiving flow collector is allowed to receive. 10. IANA Considerations IPFIX Messages use two fields with assigned values. These are the IPFIX Version Number, indicating which version of the IPFIX Protocol was used to export an IPFIX Message, and the IPFIX Set ID, indicating the type for each set of information within an IPFIX Message. The previously reserved Set ID values of TBD1 and TBD2 are used as specified in this document. All other Set ID values are reserved for future use. Set ID values above 255 are used for Data Sets. A new Information Element, "MIBObjectIdentifierMarker", needs to be reserved. 11. References 11.1. Normative References [PEN] IANA, "Private Enterprise Numbers registry", . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Johnson, et al. Expires October 9, 2011 [Page 23] Internet-Draft Exporting MIB Variables with IPFIX April 2011 [RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999. [RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group MIB", RFC 2863, June 2000. [RFC5101] Claise, B., "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information", RFC 5101, January 2008. [RFC5102] Quittek, J., Bryant, S., Claise, B., Aitken, P., and J. Meyer, "Information Model for IP Flow Information Export", RFC 5102, January 2008. 11.2. Informative References [RFC2982] Kavasseri, R., "Distributed Management Expression MIB", RFC 2982, October 2000. [RFC3444] Pras, A. and J. Schoenwaelder, "On the Difference between Information Models and Data Models", RFC 3444, January 2003. [RFC5476] Claise, B., Johnson, A., and J. Quittek, "Packet Sampling (PSAMP) Protocol Specifications", RFC 5476, March 2009. Authors' Addresses Andrew Johnson Cisco System, Inc. 96 Commercial Quay Commercial Street Edinburgh, EH6 6LX UK Phone: +44 131 561 3641 Email: andrjohn@cisco.com Johnson, et al. Expires October 9, 2011 [Page 24] Internet-Draft Exporting MIB Variables with IPFIX April 2011 Benoit Claise Cisco System, Inc. De Kleetlaan 6a b1 Diegem, 1813 Belgium Phone: +32 2 704 5622 Email: bclaise@cisco.com Paul Aitken Cisco System, Inc. 96 Commercial Quay Commercial Street Edinburgh, EH6 6LX UK Phone: +44 131 561 3616 Email: paitken@cisco.com Juergen Schoenwaelder Jacobs University Bremen Campus Ring 1 Bremen, 28725 Germany Phone: +49 421 200-3587 Email: j.schoenwaelder@jacobs-university.de Johnson, et al. Expires October 9, 2011 [Page 25]