Monitoring BGP Parameters Using BMP

Terminology This memo makes use of the terms defined in . BMP: BGP Monitoring Protocol BMS: BGP Monitoring Station Initiation message: Reports to the monitoring server such information as the router vendor and its software version.

Introduction The Border Gateway Protocol (BGP) is a dynamic routing protocol operating on an Autonomous System (AS) and typically configured on a network device. The BGP typically can support a number of optional parameters, e.g., IPv4 Unicast, IPv4 Multicast, IPv6 Unicast, and other Multiple-Protocol Extended Capabilities, Route Refresh Capability, Outbound Route Filtering Capability, Graceful Restart Capability, Support for 4-octet AS number capability etc., and the different BGP implementations may support a different number of different capabilities. The network device configured with the BGP typically may not enable all optional capabilities supported in the configured BGP, but enable some currently required BGP optional capabilities as required for a current task. The BGP Monitoring Protocol (BMP) introduces the availability of monitoring BGP running status, such as BGP peer relationship establishment and termination and route updates. Without BMP, manual query is required if you want to know about BGP running status. With BMP, a router can be connected to a monitoring station and configured to report BGP running statistics to the station for monitoring, which improves the network monitoring efficiency. BMP facilitates the monitoring of BGP running status and reports security threats in real time so that preventive measures can be taken promptly. In order to monitor and manage effectively the operating states of the BGP configured on the respective network devices in the network, the existing practice is that a monitoring station obtains BGP information of the respective network devices in the network to monitor and manage centrally the network devices configured with the BGP in the network. By way of an example of a flow in which the monitoring station obtains the BGP information, after a BGP connection is set up between network devices A and B configured with the BGP (or between peers), taking the network device A as an example, the network devices A and B negotiate about their own enabled BGP optional capabilities in OPEN messages under a BGP rule, and the network device A further includes a BGP Monitoring Protocol (BMP) module connected with the monitoring station, where the BMP module can obtain the enabled BGP optional capabilities of the network device A, and the enabled BGP capabilities of the network device B as a result of negotiation about the enabled BGP capabilities, so that if the BMP module of the network device A sends the configured BGP information of the network device to the monitoring station in a Peer Up Notification message, then the BGP optional capabilities will include only the BGP capabilities enabled on the network device A. However, sometimes it's not sufficient to report only the capabilities currently enabled at the monitored device to the BMS. In order to better optimize the network, the BMS may want to access all the capabilities that are supported at each monitored devices, as well as the current configuration informations.

Use cases

BGP Optional Parameters Supported/Enabled: The Open Message reported to BMS contains only the currently enabled capabilities at the monitored device. If all the supported capabilities of the monitored devices, both the enabled and not yet enabled ones, are informed to the BMS, the BMS can use the more comprehensive and valid inputs to make decisions about the whole network optimization. For example, if the Graceful Restart Capability is not enabled for a BGP Peer, and thus the BGP Open Message (i.e., the Peer Up Notification in BMP) would not include the GR capability. However, if the BMS or the operator has the knowledge that both devices support the GR capability, and enables it at both devices, it could improve the operational stability of the network.
BGP Default Behavior Parameters: As one of the concern from the operators, that in multi-vendor environment, some default configurations or behaviors of devices are vendor-specific, and may cause various issues during the interoperation test or any time after. Take the protocol preferences (distance) of different BGP routes for example: Vendor A assigns value 255 to eBGP, iBGP and BGP local routes by default, while vendor B assigns 20 to eBGP, 200 to iBGP and 200 to BGP local routes by default. In addition, value 255 is not recognized by vendor B, and routes assigned such distance would be ignored.

Extension of BMP Initiation Message As described in Section 4.3 of , the initiation message provides a means for the monitored router to inform the monitoring station of its vendor, software version, and so on. The initiation message consists of the common BMP header followed by two or more Information TLVs (Section 4.4 of ) containing information about the monitored router. Currently defined types are:

This document defines 3 new categories of TLV types: the BGP Optional Parameters and the BGP Default Behavior Parameters.

BGP Optional Parameters Information TLV . 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... | Parm. Type | Parm. Length | Parameter Value (variable) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-... ]]> Parameter Type is a one octet field that unambiguously identifies individual parameters. Parameter Length is a one octet field that contains the length of the Parameter Value field in octets. Parameter Value is a variable length field that is interpreted according to the value of the Parameter Type field. RFC 5492 defines the Capabilities Optional Parameter.

Default Behavior Parameters sub TLV , which is defined 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 +-------------------------------+-------------------------------+ | Default Beh. Type | Def Beh. Length | +-------------------------------+-------------------------------+ + Default Beh. Value (variable) + ~ ~ +---------------------------------------------------------------+ ]]> The Default Behavior Type is a one octet field that identifies the default behavior type parameter. Parameter Length is a one octet field that contains the length of the Parameter Value field in octets. Parameter Value is a variable length field that is interpreted according to the value of the Parameter Type field:

Type = TBD4, (32-bit integer ) Value of default Protocol Preference for Local route
Type = TBD5, (32-bit integer ) Value of default Protocol Preference for EBGP route
Type = TBD6, (32-bit integer ) Value of default Protocol Preference for IBGP route
Type = TBD7, (32-bit integer ) Value of default BGP connect-retry timer time
Type = TBD8, (32-bit integer ) Value of default BGP Keepalive time
Type = TBD9, (32-bit integer ) Value of default BGP hold time
Type = TBD10, (32-bit integer ) Value of EBGP route-update-interval
Type = TBD11, (32-bit integer ) Value of IBGP route-update- interval
Type = TBD12, (32-bit integer ) Value of Default local-preference
Type = TBD13, (32-bit integer ) Value of Default MED

Acknowledgements TBD.

IANA Considerations TBD.

Security Considerations TBD.