Virtual Routing and Forwarding

Cisco Active Network Abstraction 3.6.7 TechnologyOL-19646-01

VRFVirtual Routing and Forwarding (VRF) is an IP tetable to co-exist on the same router at the same timsame or overlapping IP addresses can be used withtable instance that can exist in one or multiple inschnology that allows multiple instances of a routing C H A P T E R

4Virtual Routing and Forwarding

This chapter describes the level of support that Cisco ANA provides for Virtual Routing and Forwarding (VRF), as follows:

Technology Description, page 4-1 Inventory and Information Model Objects (IMOs), page 4-2 Network Topology, page 4-4 Service Alarms, page 4-5

Technology Description

VPNBGP/MPLS VPNs, as defined in RFC 2547 and related drafts and standards, provide a Layer 3 VPN. With Layer 3 VPNs, each Provider Edge (PE) device acts like a set of virtual routers, one per VPN. The network provider configures the VPN membership of each PE router interface. In most cases, one port is used for multiple interfaces where each is associated with different VPNs. The port's view of the network is restricted to the VPNs of which it is a member, and it cannot address devices outside that environment. Conventional IP routing is the interface between Customer Edge (CE) and PE devices: Static routes can be provisioned on both the CE and PE, or for more complex scenarios, a routing protocol (such as RIP, OSPF or BGP) is run between CE and PE.The network provider can also establish a suitable mesh of MPLS Label Switched Paths (LSPs) between all the PE routers that need to communicate. The PE devices qualify each external IP address that they learn with a per VPN identifier, and broadcast them to all other PE routers using an extended form of BGP depending on BGP connectivity. They also include an MPLS label that is specific to the destination route (or, in some implementations, the destination port). Through this process, the PE devices build up a complete map of the VPNs and destination labels. The PE routers then use this information to route the packets across the backbone network to the correct destination within the relevant VPN.4-1 Support and Information Model Reference Manual

e. Because the routing instances are independent, the out conflict. VRF is also used to refer to a routing

tances per each VPN on a Provider Edge (PE) router.

Chapter 4 Virtual Routing and Forwarding Inventory and Information Model Objects (IMOs)VRF-Lite (Multi-VRF)VRF-Lite is an application based on VRF that extends the concept of VRF to the customer-premises router. It supports multiple, overlapping, independent routing and forwarding tables per customer. Any routing protocol supported by normal VRF can be used in a VRF-Lite CE implementation. The CE supports traffic separation between customer networks. As there is no MPLS functionality on the CE, no label exchange happens between the CE and PE.

Inventory and Information Model Objects (IMOs)This section describes the following IMOs:

Virtual Routing Forwarding (VRF) Entity (IVrf) Equivalent Routing Entry (IRoutingEntries) Virtual Routing Entry (IVrfEntry) Multi Protocol BGP Entity (IMpBgp) Equivalent Cross Virtual Routing Entry (ICrossVrf) Cross Virtual Routing Entry (ICrossVrfRoutingEntry)

Virtual Routing Forwarding (VRF) EntityThe Virtual Routing Forwarding (VRF) Entity object describes the routing and address resolution protocols independent forwarding component of a MPLS-BGP based VPN router. It is bound by its Logical Sons attribute to all the Network layer IP Interface objects among which it is routing IP Packets.

Table 4-1 Virtual Routing Forwarding (VRF) Entity (IVrf)

Attribute Name Attribute Description Scheme Polling Interval

Virtual Routing Table Array of Equivalent Routing Entries IPCore ConfigurationExported Route Targets Array of route target identifiers IPCore ConfigurationImported Route Targets Array of route target identifiers IPCore ConfigurationAddressFamilies List of the address families (IPv4, IPv6, or both) IPCore ConfigurationRoute Distinguisher Route distinguisher IPCore ConfigurationARP Entity Address Resolution Entity (ARP Entity) (see Internet Protocol) IPCore ConfigurationName VRF name IPCore ConfigurationLogical Sons Array of all IP Interfaces among which this Virtual Routing Forwarding

(VRF) Entity is routing IP packetsIPCore N/A4-2Cisco Active Network Abstraction 3.6.7 Technology Support and Information Model Reference Manual

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Chapter 4 Virtual Routing and Forwarding Inventory and Information Model Objects (IMOs)Equivalent Routing EntryThe Equivalent Routing Entry and Virtual Routing Entry objects describe a routing tables entries. Each is an array of Virtual Routing Entries sharing a single IP Subnetwork destination.

Virtual Routing Entry

Multi Protocol BGP EntityThe Multi Protocol BGP Entity object describes the BGP component of a MPLS-BGP based VPN router. It is bound by its Logical Sons attribute to all Virtual Routing Forwarding (VRF) Entity objects among which it is routing IP Packets.

Table 4-2 Equivalent Routing Entry (IRoutingEntries)


Routing Entries Array of Virtual Routing Entries sharing a single destination IPCore Configuration

Table 4-3 Virtual Routing Entry (IVrfEntry)


Next Hop BGP Address Next hop BGP IP address IPCore ConfigurationIncoming and Outgoing Inner Label

Incoming and outgoing inner MPLS label IPCore Configuration

Outer Label Outer MPLS label IPCore ConfigurationDestination IP Subnet Final destination IP subnet IPCore ConfigurationNext Hop IP Address Next hop IP address IPCore ConfigurationType Route entry type (Null, Other, Invalid, Direct, Indirect, Static) IPCore ConfigurationRouting Protocol Type Routing protocol type (Null, Other, "Local, Network Managed,

ICMP, EGP, GGP, Hello, RIP, IS-IS, ES-IS, Cisco IGRP, BBN SPF IGP, OSPF, BGP, EIGRP)

IPCore Configuration

Outgoing Interface Name Outgoing IP interface name IPCore Configuration

Table 4-4 Multi Protocol BGP Entity (IMpBgp)


BGP Identifier Border Gateway Protocol (BGP) identifier IPCore ConfigurationLocal Autonomous System Local peer autonomous system IPCore ConfigurationCross Virtual Routing Table Array of Equivalent Cross Virtual Routing Entry IPCore ConfigurationBGP Neighbors Array of BGP neighbor entries (see Routing Protocols) IPCore ConfigurationLogical Sons Array of all Virtual Routing Forwarding (VRF) Entity objects

among which this Multi Protocol BGP Entity is routing IP Packets

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Chapter 4 Virtual Routing and Forwarding Vendor-Specific Inventory and IMOsEquivalent Cross Virtual Routing EntryThe Equivalent Cross Virtual Routing Entry and Cross Virtual Routing Entry objects describe the first dimension of a cross virtual routing table, as an array of Cross Virtual Routing Entry objects sharing a single Virtual Routing Forwarding (VRF) Entity destination.

Cross Virtual Routing Entry

Vendor-Specific Inventory and IMOsThere are no vendor-specific inventory or IMOs for this technology.

Network TopologyCisco ANA discovers MPLS-BGP based Virtual Private (VPN) network topology by searching for the existence of the local Virtual Routing Forwarding (VRF) Entitys imported route targets in any remote side's VRF entity exported route targets.

Table 4-5 Equivalent Cross Virtual Routing Entry (ICrossVrf)


Virtual Routing Entries Array of Cross Virtual Routing Entry objects sharing a single destination


Virtual Routing Entity Name Virtual Routing Entity (VRF) name IPCore Configuration

Table 4-6 Cross Virtual Routing Entry (ICrossVrfRoutingEntry)


Outgoing Virtual Routing Entity Identifier

Outgoing virtual routing entity Object Identifier (OID) IPCore Configuration

Incoming and Outgoing Virtual Routing Tags

Incoming and outgoing virtual routing tags IPCore Configuration

Destination IP Subnet Final destination IP subnet IPCore ConfigurationNext Hop IP Address Next hop IP address IPCore ConfigurationType Route entry type (Null, Other, Invalid, Direct, Indirect, Static) IPCore ConfigurationRouting Protocol Type Routing protocol type (Null, Other, "Local, Network Managed,

ICMP, EGP, GGP, Hello, RIP, IS-IS, ES-IS, Cisco IGRP, BBN SPF IGP, OSPF, BGP, EIGRP)


Outgoing Interface Name Outgoing IP interface name IPCore Configuration4-4Cisco Active Network Abstraction 3.6.7 Technology Support and Information Model Reference Manual

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Chapter 4 Virtual Routing and Forwarding Service AlarmsService AlarmsThe following alarm is supported for this technology:

Duplicate IP on VPN Found/Duplicate IP on VPN Fixed. This alarm is disabled by default.For detailed information about alarms and correlation, see the Cisco Active Network Abstraction 3.6.7 User Guide.4-5Cisco Active Network Abstraction 3.6.7 Technology Support and Information Model Reference Manual

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Chapter 4 Virtual Routing and Forwarding Service Alarms4-6Cisco Active Network Abstraction 3.6.7 Technology Support and Information Model Reference Manual

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Virtual Routing and ForwardingTechnology DescriptionVPNVRFVRF-Lite (Multi-VRF)

Inventory and Information Model Objects (IMOs)Virtual Routing Forwarding (VRF) EntityEquivalent Routing EntryVirtual Routing EntryMulti Protocol BGP EntityEquivalent Cross Virtual Routing EntryCross Virtual Routing Entry

Vendor-Specific Inventory and IMOsNetwork TopologyService Alarms

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Virtual Routing and Forwarding