Connectivity at the layer 3 network layer

There are a number of discovery agents that retrieve connectivity information from OSI model layer 3 (the Network Layer). Layer 3 is responsible for routing, congestion control, and sending messages between networks.

Table 1. Layer 3 network layer agents
Agent name	Function
AlteonVRRP	VRRP is not modelled for RCA. The AlteonVRRP agent only sets tags on VRRP interfaces that show the state of Alteon routers at the time of the discovery. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
CiscoBGPTelnet	The CiscoBGPTelnet agent downloads the following BGP data from Cisco routers: Peer data: the agent retrieves iBGP and eBGP data from peer routers. Route data: the agent retrieves routing information from BGP routing tables of peer routers. This option is off by default as it will retrieve huge amounts of data from a typical service provider network. This agent also provides the option to configure a filter to specify the route data that you would like to retrieve. Note: Before enabling this agent, configure Telnet access and the Telnet helper.
CiscoFrameRelay	The CiscoFrameRelay agent discovers Frame Relay interfaces and connections between two points on Frame Relay networks that incorporate Cisco devices. Frame Relay agents should be run in conjunction with the IP layer agents if you want to add DLCI information to the interfaces of Frame Relay devices. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
CiscoOSPFTelnet	The CiscoOSPFTelnet agent is responsible for discovery of Cisco devices running the Open Shortest Path First (OSPF) protocol. This agent provides complementary information to that of the StandardOSPF agent, such as what OSFP processes are running and virtual-link information. Note: Before enabling this agent, configure Telnet access and the Telnet helper.
ExtremeESRP	The ExtremeESRP agent discovers Extreme Standby Routing Protocol (ESRP) information from Extreme routing switches. ESRP is a feature of ExtremeWare that allows multiple switches to provide redundant routing services to users. The agent relies on the `extremeEsrpTable` and `extremeEsrpNeighborTable` of the EXTREME-ESRP-MIB being correctly populated. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
FoundryVRRP	VRRP is not modelled for RCA. The FoundryVRRP agent only sets tags on VRRP interfaces that show the state of Foundry routers at the time of the discovery. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
HSRPSnmp	The HSRPSnmp agent retrieves connectivity information using SNMP by means of the MIB from routing devices that use the HSRP (Hot Stand-by Routing Protocol) Virtual IP protocol. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
InetRouting	The InetRouting agent discovers connectivity.
Interfaces	This agent is triggered by the AssocAddress agent returns. The Interfaces agent downloads interface information primarily from the interfaces table of RFC1213.mib. The information will then be written to the m_LocalNbr field of the returned entities. You can increase or decrease the number of returned variables by modifying the Interfaces.agnt. Any basic MIB variable (sysDescr, sysName, and so on) or MIB variable that is indexed by the ifIndex can be added to the OIDs to download in the .agnt file. The Interfaces agent also retrieves IPv6 interface information. You must enable the Interfaces agent if you want to use interface filtering. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
IpBackupRoutes	The IpBackupRoutes agent finds links by looking through the IpNetToMedia MIB table, which gives the physical and IP address of devices connected to the router. This agent is not enabled by default because it retrieves a large amount of information that is not essential in order to determine layer 3 connections. Furthermore, this information may be obsolete because it is downloaded from a table that is not dynamic and requires manual refresh. If you are performing a layer 2 discovery, then the server connectivity that this agent discovers is often obsolete, as it may have been superseded by switch connectivity information. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
IpForwardingTable	The IpForwardingTable agent finds links in the more recent version of the routing tables, that is, the IP Forwarding table as specified in RFC 2096. It also exploits Open Shortest Path First (OSPF) information to enhance the discovery of Juniper devices. This agent downloads elements from the routing table based on discovery scoping. The default setting assumes that the SNMP agent for a particular device supports partial matching. If the device cannot partial match, this should be specified in the DiscoRouterPartialMatchRestrictions section of the .agnt file. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
IpRoutingTable	Retrieves generic connectivity information by looking through the router routing table, as specified in RFC1213. The agent downloads elements from the routing table based on discovery scoping. The default agent setting assumes that the SNMP agents for particular devices support partial matching. If a device cannot partial match, this should be specified in the DiscoRouterPartialMatchRestrictions section of the .agnt file. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
ISISExperimental	Discovers connectivity between routers that support the experimental ISIS MIBs. This agent should be used when some of your routers are configured with netmasks of 255.255.255.255, making them unsuitable for standard discovery. Before enabling this agent, configure SNMP access and the SNMP helper. Note: This agent is deprecated in Fix Pack 17 in favour of the StandardISIS agent.
LinkStateAdvOSPF	Retrieves link state advertisements (LSAs) from OSPF routers. These LSAs are used by the CreateOSPFNetworkLSAPseudoNodes stitcher to create OSPF pseudonodes. Pseudonodes overcome the problem of full meshing when representing OSPF area in Topoviz Network Views and enables connections within OSPF areas to be visualized in a clear, uncluttered manner.
JuniperBGPTelnet	Downloads BGP information from Juniper routers. It is not enabled by default because it gathers a very specific piece of information only, that is, whether devices are route reflectors. Note: Before enabling this agent, configure Telnet access and the Telnet helper.
NetScreenInterface	The NetScreenInterface agent retrieves information about all configured interfaces in Juniper Netscreen devices. The agent retrieves information about logical interfaces and other interfaces, which is not available from the standard IF-MIB, and requires both the NETSCREEN-INTERFACE-MIB.mib and NS-VPN-MON.mib files. The agent also retrieves VPN tunnel and tunnel connectivity information that is configured in Juniper NetScreen devices. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
NetScreenIpRoutingTable	The NetScreenIpRoutingTable agent retrieves information on IP routing tables configured on Netscreen devices. The agent determines the interfaces and sub-interfaces from the interface index of the Netscreen device. This agent performs the same function as the IpRoutingTable agent, but for Netscreen devices only, in order to take account of sub-interfaces which would not be discovered correctly by the IpRoutingTable agent. The NetScreenIpRoutingTable agent uses the IP-FORWARD-MIB Standard MIB and the NETSCREEN-INTERFACE-MIB. Note: The IpRoutingTable agent does not process the Netscreen devices processed by the NetScreenIpRoutingTable agent.
NokiaVRRP	Downloads VRRP information from routers that support the Nokia interpretation of the VRRP MIB. The information retrieved includes the VRRP state, ID, primary IP and associated addresses. This information is retrieved from the following MIB variables: vrrpOperState vrrpOperMasterIpAddr vrrpAssoIpAddrRowStatus Note: Before enabling this agent, configure SNMP access and the SNMP helper.
NortelPassport	The NortelPassport agent retrieves Layer 3 connectivity and containment information from Nortel Passport switches.
RFC2787VRRP	The RFC2787VRRP agent downloads Virtual Router Redundancy Protocol (VRRP) information from routers that run RFC2787-compliant VRRP and support the RFC2787 VRRP MIB. Some Nokia firewalls support this MIB. Note: Before enabling this agent, configure SNMP access and the SNMP helper. VRRP is not modelled for RCA. This agent sets tags on VRRP interfaces that show the state of the interfaces at the time of the discovery. The agent also downloads associated IP addresses, which are used to build VRRP collections. Tip: There are two subtly different versions of the VRRP MIB. They contain the same names but with different OIDs. If this agent does not work, use the other version of the VRRP MIB.
StandardBgp	The StandardBgp agent is responsible for discovery of networks running the Border Gateway Protocol. It supports any device that complies with the standard RFC1657 (BGP4-MIB) MIB and discovers the following information: Autonomous System IDs BGP Peer connections to external peers (EBGP) BGP Peer connections to internal peers (IBGP) BGP acquired route data (not recommended) The agent definition file is configured to accept all SNMP enabled devices by default, but the agent will only accept devices that support the BGP44-MIB, bgpIdentifier MIB variable. The agent has the following additional configuration parameters in the DiscoAgentDiscoveryScoping section of its .agnt file: GetPeerData – determines whether the agent should acquire BGP Peer data (activated by default). GetRouteData – determines whether the agent should acquire BGP routes (deactivated by default). This may result in a large amount of data being discovered. The StandardBgp agent does not currently support peer groups, confederations, per VRF BGP processes, or route reflection. Note: Before enabling this agent, configure SNMP access and the SNMP helper. It is also necessary to configure the Ping helper.
StandardOSPF	The StandardOSPF agent is responsible for the discovery of networks running the Open Shortest Path First (OSPF) protocol. It will support any device that complies with the standard RFC1850. Note: Before enabling this agent, configure SNMP access and the SNMP helper.
StandardISIS	This Phase 1 discovery agent discovers connectivity between routers that support the ISIS MIB (RFC4444). The agent retrieves ISIS neighbours and ISIS area and circuit information. Before enabling this agent, configure SNMP access and the SNMP helper. The agent requires the DIFFSERV and ISIS MIBs. To install the MIBs, complete the following steps: If you do not already have the MIBs, download them from https://www.rfc-editor.org/rfc/rfc3289.txt and https://www.rfc-editor.org/rfc/rfc4444.txt. Extract the MIBs to files. Keep the lines from the beginning of the MIB definition to the end, for example: `DIFFSERV-MIB DEFINITIONS ::= BEGIN` to `END`. Remove any headers from the files. For example: `Baker, et. al. Standards Track [Page 74] RFC 3289 Differentiated Services MIB May 2002` Save the files with the ending `.MIB` in the directory $NCHOME/precision/mibs. Load the updated MIB information by running the ncp_mib command-ine application.
TraceRoute	The TraceRoute agent finds links by tracing the route taken by an ICMP ping packet with a predetermined life span. If you are using this agent, you should increase the value of m_Timeout in the DiscoPingHelperSchema.cfg configuration file, as traceroute functionality takes longer than standard ICMP. This agent is not enabled by default as it does not only operate on SNMP-enabled devices. Therefore, if this agent were switched on by default, it would trace the route to every device on the network. The result could be incomplete connectivity in a meshed environment or inaccurate connectivity in a load-balanced environment. Note: Before enabling this agent, configure SNMP access and the SNMP helper.