Table Of Contents

Cisco ANA VNE Topology

Specifications

Physical Layer

CDP (Cisco Discovery Protocol)

Traffic Signature

Topology Types

ATM

BGP

Business

Ethernet

Frame Relay

MPLS

PPP or HDLC

Physical Layer

PWE3

GRE Tunnel

VPN

Cisco ANA VNE Topology

---

This chapter describes the Cisco ANA VNE Topology, as follows:

•Specifications

•Topology Types

Specifications

The table describes the type of topologies supported by Cisco ANA and the techniques used for their discovery. The discovery has two phases:

1. Discovery of existing links.

2. For discovered links, verification that the link still exists.

The Topology Type column information relates to the type of technology that the link type is related to.

The Link Type column displays the link type as exposed by Cisco ANA.

Table 20-1 Types of Topologies Supported by Cisco ANA 

Topology Type	Link Type	Discovery Technique	Verification Technique	Description
ATM	ATM	ATM VC Counters: 1. Same Active VCs 2. VC traffic signature, see Traffic Signature.	Physical layer counters. See physical layer counters in Physical Layer.	Active VCs: Each side identifies a set of active VCs and looks for a match with the same set on another port in the network. An active VC, is a VC that has a configured level of traffic. VC Traffic Signatures: Based on the VCs counters, see Traffic Signature.
		CDP	CDP. See CDP (Cisco Discovery Protocol).
		Static	Static
ATM	PNNI	PNNI Information	None	PNNI Information: In this technique each port in the ATM switch is identified with two values: 1. Node ID. 2. Port ID.
BGP	BGP	BGP Info	BGP Info	BGP Info: In this technique the following BGP information is used as matching criteria: 1. BGP Identifier.
Business	Business	N/A	N/A	Business links are not discovered at the VNE level, but rather created in the gateway. These links represent a relationship between any two objects in the model, which can be business or network related.
Ethernet	Ethernet	MAC	Ethernet Counters and physical layer counters. See physical layer counters in Physical Layer.	MAC: In this technique the Ethernet port MAC is tested to be the only one learned on other Ethernet port (using bridge and ARP tables). This technique discover links between two routers and links between the router and switch, but not between two switches. Ethernet Counters: Based on the Unicast Packets traffic signature, see Traffic Signature.
		CDP	CDP. See CDP (Cisco Discovery Protocol).
		Static	Static
Frame Relay	Frame Relay	Not Supported	Physical layer counters. See physical layer counters in Physical Layer.	Frame Relay links can be discovered dynamically only between Cisco devices with CDP enabled, or using static or manual configuration (Physical link discovery).
		CDP	CDP. See CDP (Cisco Discovery Protocol).
		Static	Static
MPLS	MPLS	IP Information	IP Information	IP Information: In this technique the IP address of these multiple MPLS interfaces are checked to be in the same subnet.
PPP or HDLC	PPP or HDLC	IP Information	IP Information and physical layer counters. See physical layer counters in Physical Layer.	IP Information: In this technique the IP address of this multiple PPP or HDLC interfaces are checked to be in the same subnet.
		CDP	CDP. See CDP (Cisco Discovery Protocol).
		Static	Static
Physical Layer	Physical Layer	A physical link is not discovered independently. Physical links are created as a result of the discovery of Layer 2 links, such as ATM and Ethernet.	Physical Layer Counters	By default the physical layer does not have specific techniques for discovery. Special cases are: 1. Ports from the same device will not be connected. 2. In Cisco devices if CDP is enabled it will be used. 3. Static topology may be used in the physical layer. For more information see Physical Layer. Physical Layer Counters: Based on the port traffic signature, using Octet based, or Octet and Packet based traffic, see Traffic Signature. Note In the discovery phase of physical topology Same Device test: In this technique the port is tested to be in separate VNEs depending on the type of managed equipment.
		CDP	CDP. See CDP (Cisco Discovery Protocol).
		Static	Static
PWE3 (Martini)	Tunnel	PWE3 Information	PWE3 Information	PWE3 Information: In this technique each pseudo wire is identified by the following criteria: 1. Local and Remote router IP. 2. Tunnel ID. The matching between two pseudo wire tunnels Pw1 and Pw2 is done by comparing: 1. The Pw1 local IP to Pw2 remote IP and Pw1 remote IP to Pw2 local IP. 2. Tunnel ID.
GRE Tunnel	Tunnel GRE	GRE Tunnel Information	GRE Tunnel Information	GRE Tunnel Information: In this technique each GRE tunnel is identified by the following criteria: 1. Source IP. 2. Destination IP. The matching between two tunnels T1 and T2 is done by comparing the T1 source to T2 destination and T1 destination to T2 source.
VPN (VRF)	VPN	Route Targets	Route Targets	Route Targets: In this technique each VRF is identified with the set of its import and export route targets. The matching criteria between two VRF entities will have at least one pair of Import or Export route targets of the one VRF to the Export or Import of the other VRF.

Physical Layer

In Cisco ANA's topology discovery implementation, the physical layer (Layer 1) discovery is coupled with data link layer (Layer 2) discovery. By default the physical layer does not have techniques for discovery, but rather complements the discovery of Layer 2, in the following ways:

•Ports from the same device are not connected, this validation is done in the physical layer.

•If static topology is configured it is used in the physical layer.

In addition the physical layer is used for topology verification, namely, if a link has already been discovered, it is tested periodically. This verification is done in the physical layer using counters. physical layer counters are based on the port traffic signature, using octet-based or octet and packet-based traffic.

CDP (Cisco Discovery Protocol)

For Cisco devices if CDP is enabled the CDP technique has a higher priority and it is the only one used for discovery and verification. This includes any upper layer techniques, such as VC related techniques in ATM or MAC in Ethernet.

In this technique the matching criteria is the CDP neighboring information.

Traffic Signature

Traffic signature is based on traffic pattern analysis. The underlying assumption of the traffic pattern analysis is that network traffic variety ensures that every active link or active ATM VC in the network maintains a differential traffic "fingerprint".

Consequently, any two connected ports or VCs will have similar trend functions, which can be matched within reliable statistical significance.

Topology Types

The following topology types are described in this section:

•ATM

•BGP

•Business

•Ethernet

•Frame Relay

•MPLS

•PPP or HDLC

•Physical Layer

•PWE3

•GRE Tunnel

•VPN

ATM

ATM topology represents a link between two ATM ports which are connected in the network. In the VNE model the end points of the link are ATM IMOs (ATM Interface (IAtm)) which represent the ATM port or interface.

BGP

BGP topology represents a TCP connection between two BGP entities which facilitate the "BGP neighborhood" in the network. In the VNE model the end points of the link are the MPBgp IMOs (Multi Protocol BGP Entity (IMpBgp)), which represent the BGP service running on the router.

Business

Business topology does not represent any specific link or relationship in the network. It can represent the relationship between any two objects in the model, which can be a business object or network objects. These links are created in the gateway.

Ethernet

Ethernet topology represents a link between two Ethernet ports, which are connected in the network. In the VNE model the end points of the link are Ethernet IMOs (Ethernet Interface (IEthernet)), which represent the Ethernet ports.

Frame Relay

Frame Relay topology represents a link between two Frame Relay ports, which are connected in the network. In the VNE model the end points of the link are FrameRelay IMOs (Frame Relay Interface (IFrameRelay/IFrTrunk)), which represent the Frame Relay ports.

MPLS

MPLS topology represents adjacent MPLS interfaces in the network, such adjacency represents that these MPLS interfaces forward MPLS (labels) traffic between them. Labels may be learned using discovery protocols, such as LDP, TDP (Cisco) or even be manually configured. In the VNE model the end points of the link are MPLS IMOs (MPLS Interface (IMpls)), which represent the MPLS interfaces.

PPP or HDLC

PPP or HDLC topology represents a link between two PPP or HDLC ports, which are connected in the network. In the VNE model the end points of the link are PPP and HDLC IMOs (High Level Data Link Control Encapsulation (IEncapsulation), which represent the ports.

Physical Layer

Physical Layer topology represents a link between the physical layers of two ports connected in the network. In the VNE model the end points are IMOs, which inherit from the physical layer 1 IMOs (Serial Interface (IPhysicalLayer)), such as SonetSdh, DS3Pdh, which represent physical layers of a port.

PWE3

PWE3 topology represents a link between the end points of an MPLS based pseudo wire tunnel in the network. In the VNE model the end points of the link are PTPLayer2MplsTunnel IMOs (PTP Layer 2 MPLS Tunnel Interface (IPTPLayer2MplsTunnel)), which represent the pseudo wire tunnel end points.

GRE Tunnel

GRE Tunnel topology represents a link between the end points of a GRE tunnel in the network. In the VNE model the end points of the link are TunnelGre IMOs (Generic Routing Encapsulation (GRE) Tunnel Interface (ITunnelGRE)), which represent the GRE tunnel end points.

VPN

VPN topology represents a link between two VRFs, which are part of a VPN, meaning VPN traffic can pass between customer sites connected to these VRFs. In the VNE model the end points of the link are Vrf IMOs (Virtual Routing Forwarding (VRF) Entity (IVrf)), which represent the VRF forwarding entities in the network element.