DS-Lite Management Information Base (MIB)

Dual-Stack Lite [RFC6333] is a solution to offer both IPv4 and IPv6 connectivity to customers crossing an IPv6 only infrastructure. One of its key components is an IPv4-over-IPv6 tunnel, which is used to provide IPv4 connectivity across a service provider's IPv6 network. Another key component is a carrier-grade IPv4-IPv4 Network Address Translation (NAT) to share service provider IPv4 addresses among customers. This document defines a portion of the Management Information Base (MIB) for using with network management protocols in the Internet community. This MIB module may be used for configuration and monitoring devices in a Dual-Stack Lite scenario.

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 when they appear in ALL CAPS. When these words are not in ALL CAPS (such as "should" or "Should"), they have their usual English meanings, and are not to be interpreted as key words.

For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of . 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 , and .

The Interfaces MIB defines generic managed objects for managing interfaces. Each logical interface (physical or virtual)has an ifEntry. Tunnels are handled by creating a logical interface (ifEntry) for each tunnel. Each DS-Lite tunnel also acts as a virtual interface, which has a corresponding entry in the IP Tunnel MIB and Interface MIB. Those corresponding entries are indexed by ifIndex. The ifOperStatus in ifTable is used to represent whether the DS-Lite tunnel function has been originated. The ifInUcastPkts defined in ifTable will represent the number of IPv4 packets that have been encapsulated into IPv6 packets sent to a B4. The ifOutUcastPkts defined in ifTable contains the number of IPv6 packets that can be decapsulated to IPv4 in the virtual interface. Also, the IF-MIB defines ifMtu for the MTU of this tunnel interface, so DS-Lite MIB does not need to define the MTU for the tunnel.

The key technologies for DS-Lite are IP in IP (IPv4-in-IPv6) tunnels and NAT (IPv4 to IPv4 translation). Notes: According to section 5.2 of , DS-Lite only defines IPv4 in IPv6 tunnels at this moment, but other types of encapsulation could be defined in the future. So this DS-Lite MIB only supports IP in IP encapsulation, if another RFC defined other tunnel types in the future, this DS-Lite MIB will be updated then. The NAT MIB is designed to carry translation from any address family to any address family, therefore it supports IPv4 to IPv4 translation. The IP Tunnel MIB is designed for managing tunnels of any type over IPv4 and IPv6 networks, therefore it supports IP in IP tunnels. However, the NAT MIB and IP Tunnel MIB together are not sufficient to support DS-Lite. This document describes the specific MIB requirements for DS-Lite, as below. In a DS-Lite scenario, the tunnel type is IP in IP, more precisely, is IPv4 in IPv6. Therefore, it is unnecessary to describe tunnel type in DS-Lite MIB. In a DS-Lite scenario, the translation type is IPv4 private address to IPv4 public address. Therefore, it is unnecessary to describe the type of address in the corresponding tunnelIfLocalInetAddress and tunnelIfRemoteInetAddress objects which are defined in the IP Tunnel MIB for DS-Lite MIB. In a DS-Lite scenario, the AFTR is not only the tunnel end concentrator, but also a 4-4 translator. Within the Address Family Transition Router (AFTR), tunnel information and translation information MUST be mapped each other. But the tunnel entry defined in the IP Tunnel MIB and the NAT mapping entry defined in the NAT MIB are not able to reflect this mapping relationship. Therefore, a combined MIB is necessary. The implementation of the IP Tunnel MIB is required for DS-Lite. The tunnelIfEncapsMethod in the tunnelIfEntry should be set to dsLite("xx"), and a corresponding entry in the DS-Lite module will exist for every tunnelIfEntry with this tunnelIfEncapsMethod. The tunnelIfRemoteInetAddress must be set to "::".

The DS-Lite MIB provides a way to monitor and manage the devices (AFTRs) in DS-Lite scenario through SNMP. The DS-Lite MIB is configurable on a per-interface basis. It depends on several parts of the IF-MIB , IP Tunnel MIB , and NAT MIB .

This Group defines objects that are needed for DS-Lite MIB.

The dsliteTunnel subtree describes managed objects used for managing tunnels in the DS-Lite scenario. Because some objects defined in the IP Tunnel MIB are "not access", a few new objects are defined in DS- Lite MIB.

The dsliteNAT subtree describes managed objects used for configuration as well as monitoring of AFTR which is capable of a NAT function. Because the NAT MIB supports the NAT management function in DS-Lite, we may reuse it in DS-Lite MIB. The dsliteNAT subtree also provides the information of mapping relationship between the tunnel entry and NAT entry by extending the IPv6 address of B4 to the natMappingTableEntry in the NAT MIB.

The dsliteInfo subtree provides statistical information for DS-Lite.

This group defines some notification objects for DS-Lite.

The dsliteTrap subtree provides trap information in DS-Lite scenario.

The dsliteConformance subtree provides conformance information of MIB objects.

This MIB module IMPORTs objects from , , , , and .

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: Notification thresholds: An attacker setting an arbitrarily low treshold can cause many useless notifications to be generated. Setting an arbitrarily high threshold can effectively disable notifications, which could be used to hide another attack. dsliteAFTRAlarmConnectNumber 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: dsliteTunnelStartAddPreLen dsliteNATBindMappingIntRealm dsliteNATBindMappingIntAddressType dsliteNATBindMappingIntAddress dsliteNATBindMappingIntPort dsliteNATBindMappingPool dsliteNATBindMappingMapBehavior dsliteNATBindMappingFilterBehavior dsliteNATBindMappingAddressPooling dsliteStatisticDiscard dsliteStatisticTransmitted dsliteStatisticIpv4Session dsliteStatisticIpv6Session 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 SHOULD provide the security features described by the SNMPv3 framework (see [RFC3410]), and implementations claiming compliance to the SNMPv3 standard MUST include full support for authentication and privacy via the User-based Security Model (USM) [RFC3414] with the AES cipher algorithm [RFC3826]. Implementations MAY also provide support for the Transport Security Model (TSM) [RFC5591] in combination with a secure transport such as SSH [RFC5592] or TLS/DTLS [RFC6353]. 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.

The MIB module in this document uses the following IANA-assigned OBJECT IDENTIFIER values recorded in the SMI Numbers registry, and the following IANA-assigned tunnelType values recorded in the IANAtunnelType-MIB registry:

Notes: As Appendix A of the IP Tunnel MIB[RFC4087] described that it has already assigned the value direct(2) to indicate the tunnel type is IP in IP tunnel, but it is still difficult to distinguish DS-Lite tunnel packets from normal IP in IP tunnel packets in the scenario of the AFTR connecting to both a DS-lite tunnel and an IP in IP tunnel.

The authors would like to thanks the valuable comments made by Suresh Krishnan, Ian Farrer, Yiu Lee, Qi Sun, Yong Cui, Dave Thaler, Tassos Chatzithomaoglou and other members of SOFTWIRE WG. This document was produced using the xml2rfc tool .