Definition of Managed Objects for the Manet Simplified Multicast Framework Relay Set Process

This memo defines a portion of the Management Information Base (MIB) for use with network management protocols in the Internet community. In particular, it describes objects for configuring aspects of a process implementing Simplified Multicast Forwarding (SMF) for Mobile Ad-Hoc Networks (MANETs). SMF provides multicast Duplicate Packet Detection (DPD) and supports algorithms for constructing an estimate of a MANET Minimum Connected Dominating Set (MCDS) for efficient multicast forwarding. The SMF-MIB also reports state information, performance information, and notifications. In addition to configuration, this additional state and performance information is useful to operators troubleshooting multicast forwarding problems.

For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 . Managed objects are accessed via a virtual information store, termed the Management Information Base or MIB. MIB objects are generally accessed through the Simple Network Management Protocol (SNMP). Objects in the MIB are defined using the mechanisms defined in the Structure of Management Information (SMI). This memo specifies a MIB module that is compliant to the SMIv2, which is described in STD 58, RFC 2578 , STD 58, RFC 2579 and STD 58, RFC 2580 .

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 RFC 2119 .

SMF provides methods for implementing Duplicate Packet Detection (DPD)-based multicast forwarding with the optional use of Connected Dominating Set (CDS)-based relay sets. The CDS provides a complete connected coverage of the nodes comprising the MANET. The Minimum CDS (MCDS) is the smallest set of MANET nodes (comprising a connected cluster) which cover all the nodes in the cluster with their transmissions. As the density of the MANET nodes increase, the fraction of nodes required in an MCDS decreases. Using the MCDS as a multicast forwarding set then becomes an efficient multicast mechanism for MANETs. Various algorithms for the construction of estimates of the MCDS exist. The Simplified Multicast Framework describes some of these. It further defines various operational modes for a node which is participating in the collective creation of the MCDS estimates. These modes depend upon the set of related MANET routing and discovery protocols and mechanisms in operation in the specific MANET node. A SMF router's MIB contains SMF process configuration parameters (e.g. specific CDS algorithm), state information (e.g., current membership in the CDS), performance counters (e.g., packet counters), and notifications.

This section describes the management model for the SMF node process. Figure 1 (reproduced from Figure 4 of ) shows the relationship between the SMF Relay Set selection algorithm and the related algorithms, processes and protocols running in the MANET nodes. The Relay Set Selection Algorithm (RSSA) can rely upon topology information gotten from the MANET Neighborhood Discovery Protocol (NHDP), from the specific MANET routing protocol running on the node, or from Layer 2 information passed up to the higher layer protocol processes.

| Selection | | | neighbor | | |______________| info |____________| \ / \ / neighbor\ / forwarding info* \ _____________ / status \ | | / `-->| Forwarding |<--' | Process | ----------------->|_____________|-----------------> incoming packet, forwarded packets interface id*, and previous hop* Figure 1: SMF Router Architecture ]]>

The following definitions apply throughout this document: Configuration Objects - switches, tables, objects which are initialized to default settings or set through the management interfaces such as defined by this MIB. Tunable Configuration Objects - objects whose values affect timing or attempt bounds on the SMF Relay Set (RS) process. State Objects - automatically generated values which define the current operating state of the SMF RS process in the router. Performance Objects - automatically generated values which help an administrator or automated tool to assess the performance of the CDS multicast process on the router and the overall multicast performance within the MANET routing domain.

This section presents the structure of the SMF-MIB module. The objects are arranged into the following groups: smfMIBNotifications - defines the notifications associated with the SMF process. smfMIBObjects - defines the objects forming the basis for the SMF-MIB. These objects are divided up by function into the following groups: Capabilities Group - This group contains the SMF objects that the device uses to advertise its local capabilities with respect to, e.g., the supported RSSAs. Configuration Group - This group contains the SMF objects that configure specific options that determine the overall operation of the SMF process and the resulting multicast performance. State Group - Contains information describing the current state of the SMF process such as the Neighbor Table. Performance Group - Contains objects which help to characterize the performance of the SMF process, typically counters for statistical computations. smfMIBConformance - defines two, i.e., minimal and full, conformance implementations for the SMF-MIB.

The textual conventions defined within the SMF-MIB are: The SmfStatus is defined within the SMF-MIB. This contains the current operational status of the SMF process on an interface. The SmfOpModeID represents an index that identifies a specific SMF operational mode. The SmfRssaID represents an index that identifies, through reference, a specific RSSA available for operation on the device.

The SMF device supports a set of capabilities. The list of capabilities which the device can advertise are: Operational Mode - topology information from NHDP, CDS-aware unicast routing or Cross-layer from Layer 2. SMF RSSA - the specific RSSA operational on the device. Note that configuration, state and performance objects related to a specific RSSA must be defined within a separate MIB.

The SMF device is configured with a set of controls. Some of the prominent configuration controls for the SMF device are: Operational Mode - determines where topology information is derived from, e.g., NHDP, CDS-aware unicast routing or Cross-layer from Layer 2. SMF RSSA - the specific RSSA operational on the device. Duplicate Packet detection for IPv4 - Identification-based or Hash-based DPD. Duplicate Packet detection for IPv6 - Identification-based or Hash-based DPD. SMF Type Message TLV - if NHDP mode is selected, then the SMF Type Message TLV MAY be included in the NHDP exchanges. SMF Address Block TLV - if NHDP mode is selected, then the SMF Address Block TLV SHOULD be included in the NHDP exchanges.

The State sub-tree reports current state information, e.g., Node RSSA State - identifies whether the node is currently in or out of the Relay Set. Neighbors Table - a table containing current one-hop neighbors and their operational RSSA.

The Performance sub-tree reports primarily counters that relate to SMF RSSA performance. The SMF performance counters consists of per node and per interface objects: Total multicast packets received. Total multicast packets forwarded. Total duplicate multicast packets detected. Per interface statistics table with the following entries: Multicast packets received. Multicast packets forwarded. Duplicate multicast packets detected.

The Notifications Sub-tree contains the list of notifications supported within the SMF-MIB and their intended purpose and utility.

The SMF-MIB module contains a number of tables which record data related to: configuration and operation of packet forwarding on the local router, configuration and operation of local MANET interfaces on the router, and configuration and operation of various RSSA algorithms for packet forwarding. The SMF-MIB module's tables are indexed via the following constructs: smfOpModeCapabilitiesID - the index identifying the SMF modes. smfRssaCapabilitiesID - the index identifying the RSSAs supported by this specific device. smfConfiguredAddrForwardingAddrType and smfConfiguredAddrForwardingFirstAddr - indexes to configured multicast addresses which are forwarded by the SMF process. smfIfIndex - the IfIndex of the interface on the local router on which SMF is configured. smfDiscoveredAddrForwardingAddrType and smfDiscoveredAddrForwardingFirstAddr - indexes to discovered multicast addresses which are forwarded by the SMF process. smfNeighborIpAddrType, smfNeighborIpAddr, and smfNeighborPrefixLen - the interface index set of specific one-hop neighbor nodes to this local router. These tables and their associated indexing are: smfOpModeCapabilitiesTable - identifies the resident set of SMF Operational Modes on this router. This table has 'INDEX { smfOpModeCapabilitiesID }. smfRssaCapabilitiesTable - contains reference to the specific set of RSSAs currently supported on this device. This table has 'INDEX { smfRssaCapabilitiesID }'. smfConfiguredAddrForwardingTable - contains information on multicast addresses which are to be forwarded by the SMF process on this device. This table has 'INDEX { smfConfiguredAddrForwardingAddrType, smfConfiguredAddrForwardingFirstAddr, smfConfiguredAddrForwardingLastAddr }'. smfInterfaceTable - describes the SMF interfaces on this device that are participating in the SMF packet forwarding process. This table has 'INDEX { smfIfIndex }'. smfDiscoveredAddrForwardingTable - contains discovered address for SMF packet forwarding. This table has 'INDEX { smfDiscoveredAddrForwardingAddrType, smfDiscoveredAddrForwardingFirstAddr }'. smfNeighborTable - describes the current neighbor nodes, their addresses and the SMF RSSA and the interface on which they can be reached. This table has 'INDEX { smfNeighborIpAddrType, smfNeighborIpAddr, smfNeighborPrefixLen }'. smfIpv4InterfaceTable - contains the IPv4 related SMF statistics per each SMF interface on this device. This table has 'INDEX { smfIfIndex }'. smfIpv6InterfaceTable - contains the IPv6 related SMF statistics per each SMF interface on this device. This table has 'INDEX { smfIfIndex }'.

The 'system' group in the SNMPv2-MIB is defined as being mandatory for all systems, and the objects apply to the entity as a whole. The 'system' group provides identification of the management entity and certain other system-wide data. The SMF-MIB does not duplicate those objects.

The textual conventions imported for use in the SMF-MIB are as follows. The MODULE-IDENTITY, OBJECT-TYPE, NOTIFICATION-TYPE, Counter32, Unsigned32, Integer32 and mib-2 textual conventions are imported from RFC 2578 . The TEXTUAL-CONVENTION, RowStatus and TruthValue textual conventions are imported from RFC 2579 . The MODULE-COMPLIANCE, OBJECT-GROUP and NOTIFICATION-GROUP textual conventions are imported from RFC 2580 . The InterfaceIndexOrZero textual convention is imported from RFC 2863 . The SnmpAdminString textual convention is imported from RFC 3411 . The InetAddress, InetAddressType and InetAddressPrefixLength textual conventions are imported from RFC 4001 .

In a sense, the SMF-MIB is a general front-end to a set of, yet to be developed, RSSA-specific MIBs. These RSSA-specific MIBs will define the objects for the configuration, state, performance and notification required for the operation of these specific RSSAs. The SMF-MIB Capabilities Group allows the remote management station the ability to query the router to discover the set of supported RSSAs.

This section discusses security implications of the choices made in this SMF-MIB module. There are a number of management objects defined in this MIB module with a MAX-ACCESS clause of read-write and/or read-create. Such objects may be considered sensitive or vulnerable in some network environments. The support for SET operations in a non-secure environment without proper protection can have a negative effect on network operations. These are the tables and objects and their sensitivity/vulnerability: 'smfAdminStatus' - this writable configuration object controls the operational status of the SMF process. If this setting is configured inconsistently across the MANET multicast domain, then delivery of multicast data may be inconsistent across the domain; some nodes may not receive multicast data intended for them. 'smfRouterIDAddrType' and 'smfRouterID' - these writable configuration objects define the ID of the SMF process. These objects should be configured with a routable address defined on the local SMF device. The smfRouterID is a logical identification that MUST be configured as unique across inter-operating SMF neighborhoods and it is RECOMMENDED to be chosen as the numerically largest address contained in a node's 'Neighbor Address List' as defined in NHDP. A smfRouterID MUST be unique within the scope of the operating MANET network regardless of the method used for selecting it. 'smfConfiguredOpMode' - this writable configuration objects define the operational mode of the SMF process. The operational mode defines how the SMF process develops its local estimate of the CDS. 'smfConfiguredRssa' - this writable configuration object sets the specific Reduced Set Selection Algorithm (RSSA) for the SMF process. If this object is set inconsistently across the MANET domain, multicast delivery of data will fail. 'smfRssaMember' - this writable configuration object sets the 'interest' of the local SMF node in participating in the CDS. Setting this object to 'never(3)' on a highly highly connected device could lead to frequent island formation. Setting this object to 'always(2)' could support data ex-filtration from the MANET domain. 'smfIpv4Dpd' - this writable configuration object sets the duplicate packet detection method for forwarding of IPv4 multicast packets. 'smfIpv6Dpd' - this writable configuration object sets the duplicate packet detection method for forwarding of IPv6 multicast packets. 'smfMaxPktLifetime' - this writable configuration object sets the estimate of the network packet traversal time. If set too small, this could lead to poor multicast data delivery ratios throughout the MANET domain. 'smfDpdMaxMemorySize' - this writable configuration object sets the memory storage size (in Kilo-Bytes) for the cached DPD records for the combined IPv4 and IPv6 methods. If set too small this could lead to poor performance of the duplicate packet protection algorithms and lead to inefficient resource, e.g., link, utilization within the MANET domain. The local SMF device should protect itself against memory overruns in the event that too large a setting is requested. 'smfDpdEntryMaxLifetime' - this writable configuration object sets the maximum lifetime (in seconds) for the cached DPD records for the combined IPv4 and IPv6 methods. If the memory is running low prior to the MaxLifetimes being exceeded, the local SMF devices should purge the oldest records first. 'smfNhdpRssaMesgTLVIncluded' - this writable configuration object indicates whether the associated NHDP messages include the the RSSA Message TLV, or not. It is highly RECOMMENDED that this object be set to 'true(1)'. 'smfNhdpRssaAddrBlockTLVIncluded' - this writable configuration object indicates whether the associated NHDP messages include the the RSSA Address Block TLV, or not. The smfNhdpRssaAddrBlockTLVIncluded is optional in all cases as it depends on the existence of an address block which may not be present. If this SMF device is configured with NHDP, then this object should be set to 'true(1)'. 'smfConfiguredAddrForwardingTable' - the writable configuration objects in this table indicate which multicast IP address are to be forwarded by this SMF node. Misconfiguration of rows within this table can limit the ability of this SMF device to forward multicast data. 'smfInterfaceTable' - the writable configuration objects in this table indicate which SMF node interfaces are participating in the SMF packet forwarding process. Misconfiguration of rows within this table can limit the ability of this SMF device to forward multicast data. Some of the readable objects in this MIB module (i.e., objects with a MAX-ACCESS other than not-accessible) may be considered sensitive or vulnerable in some network environments. It is thus important to control even GET and/or NOTIFY access to these objects and possibly to even encrypt the values of these objects when sending them over the network via SNMP. These are the tables and objects and their sensitivity/vulnerability: 'smfNodeRsStatusIncluded' - this readable state object indicates that this SMF node is part of the CDS, or not. Being part of the CDS makes this node a distinguished device. It could be exploited for data ex-filtration, or denial of service attacks. 'smfDiscoveredAddrForwardingTable' - the readable state objects in this table indicate which, dynamically discovered, multicast IP address are to be forwarded by this SMF node. 'smfNeighborTable' - the readable state objects in this table indicate current neighbor nodes to this SMF node. Exposing this information to an attacker could allow the attacker easier access to the larger MANET domain. The remainder of the objects in the SMF-MIB are performance counter objects. While these give an indication of the activity of the SMF process on this node, it is not expected that exposing these values pose a security risk to the MANET network. SNMP versions prior to SNMPv3 did not include adequate security. Even if the network itself is secure (for example by using IPSec), even then, there is no control as to who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in this MIB module. Implementations MUST provide the security features described by the SNMPv3 framework (see ), including full support for authentication and privacy via the User-based Security Model (USM) with the AES cipher algorithm . Implementations MAY also provide support for the Transport Security Model (TSM) in combination with a secure transport such as SSH or TLS/DTLS . Further, deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security. It is then a customer/operator responsibility to ensure that the SNMP entity giving access to an instance of this MIB module is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them.

This document describes objects for configuring parameters of the Simplified Multicast Forwarding process on a Mobile Ad-Hoc Network (MANET) router. This MIB module, denoted SMF-MIB, also reports state and performance information and notifications. This section provides some examples of how this MIB module can be used in MANET network deployments. A fuller discussion of MANET network management use cases and challenges will be provided elsewhere. SMF is designed to allow MANET routers to forward IPv4 and IPv6 packets over the MANET and cover the MANET nodes through the automatic discovery of efficient estimates of the Minimum Connected Dominating Set (MCDS) of nodes within the MANET. The MCDS are estimated using the Relay Set Selection Algorithms (RSSAs) discussed within this document. In the following, three scenarios are listed where this MIB module is useful, i.e., For a Parking Lot Initial Configuration Situation - it is common for the vehicles comprising the MANET being forward deployed at a remote location, e.g., the site of a natural disaster, to be off-loaded in a parking lot where an initial configuration of the networking devices is performed. The configuration is loaded into the devices from a fixed location Network Operation Center (NOC) at the parking lot and the vehicles are stationary at the parking lot while the configuration changes are made. Standards-based methods for configuration management from the co-located NOC are necessary for this deployment option. The set of interesting configuration objects for the SMF process are listed within this MIB module. For Mobile vehicles with Low Bandwidth Satellite Link to a Fixed NOC - Here the vehicles carrying the MANET routers carry multiple wireless interfaces, one of which is a relatively low-bandwidth on-the-move satellite connection which interconnects a fix NOC to the nodes of the MANET. Standards-based methods for monitoring and fault management from the fixed NOC are necessary for this deployment option. For Fixed NOC and Mobile Local Manager in Larger Vehicles - for larger vehicles, a hierarchical network management arrangement is useful. Centralized network management is performed from a fixed NOC while local management is performed locally from within the vehicles. Standards-based methods for configuration, monitoring and fault management are necessary for this deployment option.

The MIB module in this document uses the following IANA-assigned OBJECT IDENTIFIER value recorded in the SMI Numbers registry:

Descriptor OBJECT IDENTIFIER value ---------- ----------------------- SMF-MIB { experimental XXXX } IANA EDITOR NOTE: please assign XXXX, and remove this note.

This MIB document uses the template authored by D. Harrington which is based on contributions from the MIB Doctors, especially Juergen Schoenwaelder, Dave Perkins, C.M.Heard and Randy Presuhn.

The authors would like to acknowledge the valuable comments from Sean Harnedy in the early phases of the development of this MIB-module. The authors would like to thank James Nguyen for his careful review and comments on this MIB-module and his work on the definitions of the follow on MIB-modules to configure specific RSSA algorithms related to SMF. Further, the authors would like to acknowledge to work of James Nguyen, Brian Little, Ryan Morgan and Justin Dean on their software development of the SMF-MIB.