Overview
Describes how OMP learns and advertises vRoutes (prefixes) and TLOCs (transport locations) to establish network reachability.
On Cisco Catalyst SD-WAN Controllers and Cisco IOS XE Catalyst SD-WAN devices, OMP advertises to its peers and services the routes it has learned from its local site, along with their corresponding transport location mappings, which are called TLOCs. These routes, known as OMP routes or vRoutes, are tuples consisting of the route and its associated TLOC. The Cisco Catalyst SD-WAN Controllers learns the topology of the overlay network and the services available in the network through OMP routes.
OMP interacts with traditional routing at local sites in the overlay network. It imports information from traditional routing protocols, such as OSPF and BGP, and this routing information provides reachability within the local site. The importing of routing information from traditional routing protocols is subject to user-defined policies.
In an overlay networking environment, OMP uses a different notion of routing peers than in traditional networks. Logically, the overlay environment consists of a centralized controller and several edge devices.
Each edge device advertises its imported routes to the centralized controller and based on policy decisions, this controller distributes the overlay routing information to other edge devices in the network. Edge devices do not advertise routing information to each other using OMP or any other method. The OMP peering sessions between the centralized controller and the edge devices are exclusively for exchanging control plane traffic. They do not transmit data traffic.
Registered edge devices automatically collect routes from directly connected networks, static routes, and routes learned from IGP protocols. The edge devices can also be configured to collect routes learned from BGP.
When route maps are configured for protocol redistribution, AS path and community configuration—such as AS path prepend—are not supported. To configure and apply the AS path for redistributed OMP routes, use a route map on the BGP neighbor outbound policy.
OMP performs path selection, loop avoidance, and policy implementation on each local device to decide which routes are installed in the local routing table of any edge device.
Route advertisements to OMP are done by applying the configuration at the global level or at the specific VPN level. To configure route advertisements to OMP at the global level, use the OMP feature template. On the other hand, to configure route advertisements to OMP at the specific VPN level, use the VPN feature template. For more information about configuring route advertisements to OMP, see Configure OMP using templates.
Any recursive lookup for service side routes over OMP protocol is not supported on Cisco Catalyst SD-WAN. Starting from Cisco IOS XE Catalyst SD-WAN Release 17.12.1a, the recursive route lookup on service side routes over OMP protocol is not supported.
In releases prior to Cisco IOS XE Catalyst SD-WAN Release 17.18.1a, controllers experience high CPU and memory usage in large-scale environments. It is recommended to avoid running commands that generate large outputs. Such commands can place substantial load on the system, potentially causing temporary delays or disruptions in command execution. High resource utilization in these situations may result in longer convergence times or, in some cases, process instability.
The system is designed to recover automatically once CPU and memory activity return to normal. To minimize operational impact, monitor system resources and schedule commands thoughtfully.
OMP advertises these types of routes:
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OMP routes (also called vRoutes): Prefixes that establish reachability between end points that use the OMP-orchestrated transport network. OMP routes can represent services in a central data center, services at a branch office, or collections of hosts and other end points in any location of the overlay network. OMP routes require and resolve into TLOCs for functional forwarding. In comparison with BGP, an OMP route is the equivalent of a prefix carried in any of the BGP AFI/SAFI NLRI fields (Address Family Indicator (AFI), Subsequent Address Family Identifiers (SAFI), Network Layer Reachability Information (NLRI)) fields).
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Transport locations (TLOCs): Identifiers that tie an OMP route to a physical location. The TLOC is the only entity of the OMP routing domain that is visible to the underlying network, and it must be reachable via routing in the underlying network. A TLOC can be directly reachable via an entry in the routing table of the physical network, or it can be represented by a prefix residing on the outside of a NAT device and must be included in the routing table. In comparison with BGP, the TLOC acts as the next hop for OMP routes.
This figure illustrates the two types of OMP routes.
OMP routes
Each device at a branch or local site advertises OMP routes to the Cisco Catalyst SD-WAN Controllers in its domain. These routes contain routing information that the device has learned from its site-local network.
A Cisco IOS XE Catalyst SD-WAN device can advertise one of the following types of site-local routes:
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Connected (also known as direct)
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Static
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BGP
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EIGRP
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LISP
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OSPF (inter-area, intra-area, and external)
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OSPFv3 (inter-area, intra-area, and external)
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IS-IS
OMP routes advertise these attributes:
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TLOC: Transport location identifier of the next hop for the vRoute. It is similar to the BGP NEXT_HOP attribute. A TLOC consists of three components:
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System IP address of the OMP speaker that originates the OMP route.
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Color to identify the link type.
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Encapsulation type on the transport tunnel.
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System IP: System IP address of the OMP speaker that originates the OMP route. Only applicable to optimized advertisement. Fo rmore information, see OMP vRoute advertisement optimization using system path.
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Origin: Source of the route, such as BGP, OSPF, connected, and static, and the metric associated with the original route.
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Originator: OMP identifier of the originator of the route, which is the IP address from which the route was learned.
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Preference: Degree of preference for an OMP route. A higher preference value is more preferred.
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Site ID: Identifier of a site within the Cisco Catalyst SD-WAN overlay network domain to which the OMP route belongs.
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Tag: Optional, transitive path attribute that an OMP speaker can use to control the routing information it accepts, prefers, or redistributes.
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VRF: VRF or network segment to which the OMP route belongs.
You configure some of the OMP route attribute values, including the system IP, color, encapsulation type, carrier, preference, service, site ID, and VRF. You can modify some of the OMP route attributes by provisioning control policy on the Cisco Catalyst SD-WAN Controller.
TLOC routes
TLOC routes identify transport locations. These are locations in the overlay network that connect to physical transport, such as the point at which a WAN interface connects to a carrier. A TLOC is denoted by a 3-tuple that consists of the system IP address of the OMP speaker, a color, and an encapsulation type. OMP advertises each TLOC separately.
TLOC routes advertise these attributes:
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TLOC private address: Private IP address of the interface associated with the TLOC.
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TLOC public address: NAT-translated address of the TLOC.
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Carrier: An identifier of the carrier type, which is generally used to indicate whether the transport is public or private.
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Color: Identifies the link type.
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Encapsulation type: Tunnel encapsulation type.
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Preference: Degree of preference that is used to differentiate between TLOCs that advertise the same OMP route.
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Site ID: Identifier of a site within the Cisco Catalyst SD-WAN overlay network domain to which the TLOC belongs.
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Tag: Optional, transitive path attribute that an OMP speaker can use to control the flow of routing information toward a TLOC. When an OMP route is advertised along with its TLOC, both or either can be distributed with a community TAG, to be used to decide how to send traffic to or receive traffic from a group of TLOCs.
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Weight: Value that is used to discriminate among multiple entry points if an OMP route is reachable through two or more TLOCs.
The IP address used in the TLOC is the fixed system address of the device itself. The reason for not using an IP address or an interface IP address to denote a TLOC is that IP addresses can move or change; for example, they can be assigned by DHCP, or interface cards can be swapped. Using the system IP address to identify a TLOC ensures that a transport end point can always be identified regardless of IP addressing.
The link color represents the type of WAN interfaces on a device. The Cisco Catalyst SD-WAN solution offers predefined colors, which are assigned in the configuration of the devices. The color can be one of default, 3g, biz-internet, blue, bronze, custom1, custom2, custom3, gold, green, lte, metro-ethernet, mpls, private1, private2, public-internet, red, or silver.
The encapsulation is the one used on the tunnel interface. It can be either IPsec or GRE.
You configure some of the TLOC attributes, including the system IP address, color, and encapsulation, and you can modify some of them by provisioning control policy on the Cisco Catalyst SD-WAN Controller. See Centralized Control Policy.