Supported Protocols
This section explains the protocols supported for unicast routing.
OMP Routing Protocol
The Cisco Catalyst SD-WAN Overlay Management Protocol (OMP) is the protocol responsible for establishing and maintaining the Cisco Catalyst SD-WAN control plane. It provides the following services:
-
Orchestration of overlay network communication, including connectivity among network sites, service chaining, and VPN or VRF topologies
-
Distribution of service-level routing information and related location mappings
-
Distribution of data plane security parameters
-
Central control and distribution of routing policy
OMP is the control protocol that is used to exchange routing, policy, and management information between Cisco Catalyst SD-WAN Controllers and Cisco IOS XE Catalyst SD-WAN devices in the overlay network. These devices automatically initiate OMP peering sessions between themselves, and the two IP end points of the OMP session are the system IP addresses of the two devices.
OMP is an all-encompassing information management and distribution protocol that enables the overlay network by separating services from transport. Services provided in a typical VRF setting are usually located within a VRF domain, and they are protected so that they are not visible outside the VRF. In such a traditional architecture, it is a challenge to extend VRF domains and service connectivity.
OMP addresses these scalability challenges by providing an efficient way to manage service traffic based on the location of logical transport end points. This method extends the data plane and control plane separation concept from within routers to across the network. OMP distributes control plane information along with related policies. A central Cisco Catalyst SD-WAN Controller makes all decisions related to routing and access policies for the overlay routing domain. OMP is then used to propagate routing, security, services, and policies that are used by edge devices for data plane connectivity and transport.
OMP Route Advertisements
On Cisco Catalyst SD-WAN Controllers and Cisco IOS XE Catalyst SD-WAN devices, OMP advertises to its peers the routes and services that it has learned from its local site, along with their corresponding transport location mappings, which are called TLOCs. These routes are called OMP routes or vRoutes to distinguish them from standard IP routes. The routes advertised are actually a tuple consisting of the route and the TLOC associated with that route. It is through OMP routes that the Cisco Catalyst SD-WAN Controllers learn the topology of the overlay network and the services available in the network.
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.
Because OMP operates in an overlay networking environment, the notion of routing peers is different from a traditional network environment. From a logical point of view, the overlay environment consists of a centralized controller and a number of 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 never advertise routing information to each other, either using OMP or any other method. The OMP peering sessions between the centralized controller and the edge devices are used exclusively to exchange control plane traffic; they are never, in any situation, used for data traffic.
Registered edge devices automatically collect routes from directly connected networks as well as static routes and routes learned from IGP protocols. The edge devices can also be configured to collect routes learned from BGP.
Route map AS path and community configuration, for example, AS path prepend, are not supported when route-maps are configured for protocol redistribution. The AS path for redistributed OMP routes can be configured and applied by using 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.
Note |
Route advertisements to OMP are done by either 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. |
Note |
Any recursive lookup for service side routes over OMP protocol is not supported on Cisco Catalyst SD-WAN. Starting from Cisco IOS XE SD-WAN Release 17.12.1a, the recursive route lookup on service side routes over OMP protocol on Cisco IOS XE Catalyst SD-WAN is supported. |
OMP advertises the following types of routes:
-
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).
-
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.
The following 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 Catalyst SD-WAN device can advertise one of the following types of site-local routes:
-
Connected (also known as direct)
-
Static
-
BGP
-
EIGRP
-
LISP
-
OSPF (inter-area, intra-area, and external)
-
OSPFv3 (inter-area, intra-area, and external)
-
IS-IS
OMP routes advertise the following attributes:
-
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:
-
System IP address of the OMP speaker that originates the OMP route
-
Color to identify the link type
-
Encapsulation type on the transport tunnel
-
-
Origin—Source of the route, such as BGP, OSPF, connected, and static, and the metric associated with the original route.
-
Originator—OMP identifier of the originator of the route, which is the IP address from which the route was learned.
-
Preference—Degree of preference for an OMP route. A higher preference value is more preferred.
-
Site ID—Identifier of a site within the Cisco Catalyst SD-WAN overlay network domain to which the OMP route belongs.
-
Tag—Optional, transitive path attribute that an OMP speaker can use to control the routing information it accepts, prefers, or redistributes.
-
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 the following attributes:
-
TLOC private address—Private IP address of the interface associated with the TLOC.
-
TLOC public address—NAT-translated address of the TLOC.
-
Carrier—An identifier of the carrier type, which is generally used to indicate whether the transport is public or private.
-
Color—Identifies the link type.
-
Encapsulation type—Tunnel encapsulation type.
-
Preference—Degree of preference that is used to differentiate between TLOCs that advertise the same OMP route.
-
Site ID—Identifier of a site within the Cisco Catalyst SD-WAN overlay network domain to which the TLOC belongs.
-
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.
-
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 that 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.
OMP Route Advertisements for Cisco Catalyst SD-WAN Controllers
Feature Name |
Release Information |
Description |
---|---|---|
Increased OMP Path Limit for Cisco Catalyst SD-WAN Controllers |
Cisco IOS XE Catalyst SD-WAN Release 17.5.1a |
This feature extends the limit on the number of OMP routes that can be exchanged between Cisco Catalyst SD-WAN Controllers to 128. Prior to this release, the limit was 16. |
Overview
The transport location (TLOC) information is advertised to the OMP peers including Cisco Catalyst SD-WAN Controllers and its local-site branches. Starting from Cisco IOS XE Catalyst SD-WAN Release 17.5.1a , the limit on the number of OMP paths that can be exchanged between Cisco Catalyst SD-WAN Controllers per VPN per prefix is extended to a maximum of 128.
Limitations
-
Multitenant Cisco Catalyst SD-WAN Controllers only support global OMP configuration.
-
The number of paths that are shared is dependent upon factors such as memory and the organization of internal data structure.
Configure Path Limit
The following example shows how to configure the number of paths that a Cisco Catalyst SD-WAN Controller can send to another Cisco Catalyst SD-WAN Controller:
Device(config)# omp
Device(config-omp)# controller-send-path-limit 100
Use the controller-send-path-limit command to configure maximum 128 send path limit to be exchanged between Cisco Catalyst SD-WAN Controllers. Use the no form of this command to set the send path limit to default. The default configuration enables the controllers to send the information of all the paths available up to maximum of 128.
Note |
We recommend using the default configuration, which sends information about all available paths, subject to a limit of 128 paths. This ensures that you have network visibility across controllers. We recommend not to change the path limit frequently. For any changes on the peers, Cisco Catalyst SD-WAN Controller performs a full route database update. This leads to complete network updates. |
For more information about configuring path limits, see controller-send-path-limit command page.
OMP Route Redistribution
OMP automatically redistributes the following types of routes that it learns either locally or from its routing peers:
-
Connected
-
Static
-
OSPF intra-area routes
-
OSPF inter-area routes
-
OSPFv3 intra-area routes (Address-Family IPv6)
-
OSPFv3 inter-area routes (Address-Family IPv6)
To avoid routing loops and less than optimal routing, redistribution of following types of routes requires explicit configuration:
-
BGP
-
EIGRP
-
LISP
-
IS-IS
-
OSPF external routes
-
OSPFv3 external route (Address-Family IPv6)
-
OSPFv3 all routes (Address-Family IPv4)
The advertise network<ipv4-prefix> command can be used to advertise a specific prefix when a non-OMP route corresponding to the prefix is present in the VRF IPv4 routing table. Note that this command is only supported for address-family ipv4 .
The following is an example for advertise network configuration:
omp
no shutdown
graceful-restart
address-family ipv4 vrf 1
advertise connected
advertise static
advertise network X.X.X.X/X
!
To avoid propagating excessive routing information from the edge to the access portion of the network, the routes that devices receive via OMP are not automatically redistributed into the other routing protocols running on the routers. If you want to redistribute the routes received via OMP, you must enable this redistribution locally on each device.
OMP sets the origin and sub-origin type in each OMP route to indicate the route's origin (see the table below). When selecting routes, the Cisco Catalyst SD-WAN Controller and the router take the origin type and subtype into consideration.
To configure redistribution of OSPF routes into OMP for VRF1, you need to configure advertise ospf route-map <route-map-name> external. The OSPF internal routes are redistributed into OMP by default without any explicit configuration.
The following example shows the redistribution of OSPF external routes on all VRFs:
omp
no shutdown
ecmp-limit 6
graceful-restart
no as-dot-notation
timers
holdtime 300
graceful-restart-timer 120
exit
address-family ipv4
advertise ospf external <-- This configuration implies OSPF Inter-Area/Intra-Area routes & External routes are redistributed into OMP
advertise connected
advertise static
!
The following example shows the redistribution of OSPF external routes for a specific VRF:
omp
no shutdown
ecmp-limit 6
graceful-restart
no as-dot-notation
timers
holdtime 300
graceful-restart-timer 120
exit
address-family ipv4 vrf 1
advertise ospf external
advertise ospf route-map RLB
!
With the external keyword, the configuration applies the supplied route-map to both external and internal OSPF routes (Intra-Area/Inter-Area).
The following example shows the redistribution of OSPFv3 external routes:
omp
no shutdown
ecmp-limit 6
graceful-restart
no as-dot-notation
timers
holdtime 300
graceful-restart-timer 120
exit
address-family ipv6
advertise ospfv3
advertise ospf external
!
Note |
Starting from Cisco IOS XE Catalyst SD-WAN Release 17.7.2, the real-time display of omp routes received and advertised in Cisco SD-WAN Manager are limited to only 4001 routes to avoid excessive CPU usage. |
OMP Route Origin Type |
OMP Route Origin Subtype |
---|---|
BGP |
External Internal |
Connected |
— |
OSPF |
Intra-area, Inter-area, External-1, External-2, NSSA-External-1 and NSSA-External-2 |
OSPFv3 |
Intra-area, Inter-area, External-1, External-2, NSSA-External-1 and NSSA-External-2 |
Static |
— |
EIGRP |
|
LISP |
— |
IS-IS |
Level 1 and level 2 |
OMP also carries the metric of the original route. A metric of 0 indicates a connected route.
Administrative Distance
Administrative distance is the metric used to select the best path when there are two or more different routes to the same destination from multiple routing protocols. When the Cisco Catalyst SD-WAN Controller or the router is selecting the OMP route to a destination, it prefers the one with the lowest administrative distance value.
The following table lists the default administrative distances used by the Cisco Catalyst SD-WAN devices:
Protocol |
Administrative Distance |
---|---|
Connected |
0 |
Static |
1 |
NAT (NAT and static routes cannot coexist in the same VPN; NAT overwrites static routes) |
1 |
Learned from DHCP |
1 |
EIGRP Summary |
5 |
EBGP |
20 |
EIGRP |
Internal: 90, External: 170 |
OSPF |
110 |
OSPFv3 |
110 |
IS-IS |
115 |
IBGP |
200 |
OMP |
251 |
OMP Best-Path Algorithm
Cisco Catalyst SD-WAN devices advertise their local paths to the Cisco Catalyst SD-WAN Controller using OMP. Depending on the network topology, some paths might be advertised from multiple devices. Cisco Catalyst SD-WAN devices use the following algorithm to choose the best path:
Step |
Applies to |
Description |
||
---|---|---|---|---|
1 |
Edge devices Cisco Catalyst SD-WAN Controller |
Path validity Check whether the OMP path is valid. If not, ignore it. |
||
2 |
Edge devices Cisco Catalyst SD-WAN Controller |
Active vs. stale paths Prefer an active path over a stale path. An active path is a one from a peer with which an OMP session is up. A stale path is one from a peer with which an OMP session is in Graceful Restart mode.
|
||
3 |
Edge devices |
Administrative distance Select the OMP path with the lower administrative distance. Example: A path that the device learns locally via BGP would be preferred over a path that it learns from a Cisco SD-WAN Controller via OMP. For information about administrative distance, see Administrative Distance. |
||
4 |
Edge devices Cisco Catalyst SD-WAN Controller |
OMP path preference Select the OMP path with the higher OMP path preference value. |
||
5 |
Cisco Catalyst SD-WAN Controller |
Access region Cisco SD-WAN Controller drops advertisement from border router (BR) to BR in the same region. |
||
6 |
Edge devices |
Core region Cisco SD-WAN Controller allows advertisement between BRs in the same access region, but receiving BR drops advertisement. |
||
7 |
Multi-Region Fabric scenario only Edge devices |
Region path length Compare region-path-length. Prefer lower. If region-path-length-ignore is configured, then skip this step. (This addresses secondary regions in Multi-Region Fabric.) |
||
8 |
Multi-Region Fabric scenario only Border routers |
Access region vs. core region Prefer access region paths over core region paths. |
||
9 |
Edge devices |
Direct vs. transport gateway path Prefer a direct path over a transport gateway path. This step can be modified by the transport gateway path preference options, which can (a) cause the transport gateway path to be preferred, or (b) result in the paths to be considered equal. See Configure the Transport Gateway Path Preference in the Cisco Catalyst SD-WAN Multi-Region Fabric (also Hierarchical SD-WAN) Configuration Guide. |
||
10 |
Multi-Region Fabric scenario only Edge devices |
Multi-Region Fabric subregion comparison
|
||
11 |
Multi-Region Fabric scenario only Edge devices |
Border router preference Prefer a path with a higher border router preference value. |
||
12 |
Edge devices |
Derived affinity Prefer a path with a lower derived affinity value. |
||
13 |
Edge devices with an affinity preference configured |
Affinity preference Depending on the affinity preference configured on the device, prefer a path whose affinity is earlier in the preference list (higher priority). If the device uses affinity-preference-auto, then prefer a path with a numerically lower affinity group.
|
||
14 |
Edge devices |
TLOC preference Select an OMP path with a higher TLOC preference value. |
||
15 |
Edge devices Cisco Catalyst SD-WAN Controller |
Origin type and subtype Compare the origin type and subtype, and select the first match in the following list:
|
||
16 |
Edge devices Cisco Catalyst SD-WAN Controller |
Origin metric Select an OMP path that has a lower origin metric. |
||
17 |
Cisco Catalyst SD-WAN Controller |
Path source Prefer a path sourced from an edge router over the same path coming from a Cisco Catalyst SD-WAN Controller. |
||
18 |
Edge devices Cisco Catalyst SD-WAN Controller |
Private IP address If the router IDs are equal, a Cisco IOS XE Catalyst SD-WAN device selects the OMP path with the lower private IP address. If a Cisco Catalyst SD-WAN Controller receives the same prefix from two different sites and if all attributes are equal, it chooses both of them. |
Note |
From all equal cost multi-paths for a given prefix selected as a best-paths and accepted by policy, advertise not more than number of paths specified in send-path-limit. |
Here are some examples of choosing the best path:
-
A Cisco Catalyst SD-WAN Controller receives an OMP path to 10.10.10.0/24 via OMP from a Cisco IOS XE Catalyst SD-WAN device with an origin code of OSPF, and it also receives the same path from another Cisco Catalyst SD-WAN Controller, also with an origin code of OSPF. If all other things are equal, the best-path algorithm chooses the path that came from the Cisco IOS XE Catalyst SD-WAN device.
-
A Cisco Catalyst SD-WAN Controller learns the same OMP path, 10.10.10.0/24, from two Cisco IOS XE Catalyst SD-WAN devices in the same site. If all other parameters are the same, both paths are chosen and advertised to other OMP peers. By default, up to four equal-cost paths are selected and advertised.
A Cisco IOS XE Catalyst SD-WAN device installs an OMP path in its forwarding table (FIB) only if the TLOC to which it points is active. For a TLOC to be active, an active BFD session must be associated with that TLOC. BFD sessions are established by each device which creates a separate BFD session with each of the remote TLOCs. If a BFD session becomes inactive, the Cisco Catalyst SD-WAN Controller removes from the forwarding table all the OMP paths that point to that TLOC.
OMP Graceful Restart
Graceful restart for OMP allows the data plane in the Cisco Catalyst SD-WAN overlay network to continue functioning if the control plane stops functioning or becomes unavailable. With graceful restart, if the Cisco SD-WAN Controller in the network goes down, or if multiple Cisco SD-WAN Controllers go down simultaneously, Cisco IOS XE Catalyst SD-WAN device can continue forwarding data traffic. They do this using the last known good information that they received from the Cisco SD-WAN Controller. When a Cisco SD-WAN Controller is again available, its DTLS connection to the device is re-established, and the device then receives updated, current network information from the Cisco SD-WAN Controller.
When OMP graceful restart is enabled, Cisco IOS XE Catalyst SD-WAN devices and a Cisco SD-WAN Controller (that is, two OMP peers) cache the OMP information that they learn from their peers. This information includes OMP routes, TLOC routes, service routes, IPsec SA parameters, and centralized data policies. When one of the OMP peers is no longer available, the other peer uses the cached information to continue operating in the network. So, for example, when a device no longer detects the presence of the OMP connection to a Cisco SD-WAN Controller, the device continues forwarding data traffic using the cached OMP information. The device also periodically checks whether the Cisco SD-WAN Controller has again become available. When it does come back up and the device re-establishes a connection to it, the device flushes its local cache and considers only the new OMP information from the Cisco SD-WAN Controller to be valid and reliable. This same scenario occurs when a Cisco SD-WAN Controller no longer detects the presence of Cisco IOS XE Catalyst SD-WAN devices.
Note |
When a change to an OMP graceful restart configuration is made, the OMP session between the Cisco SD-WAN Controllers and the device is flapped. This causes all OMP routes belonging to different address families, such as TLOC, IPv4 or IPv6 unicast, IPv4 multicast, and other families to be withdrawn locally and relearned a few seconds later when the OMP session with the Cisco SD-WAN Controllers comes back up. As the TLOC routes are temporarily removed and added back, Bidirectional Forwarding Detection (BFD) sessions also flap momentarily. This is the expected behavior. |
BGP and OSPF Routing Protocols
The Cisco Catalyst SD-WAN overlay network supports BGP and OSPF unicast routing protocols. These protocols can be configured on Cisco IOS XE Catalyst SD-WAN devices in any VRF except for transport and management VRFs to provide reachability to networks at their local sites. Cisco IOS XE Catalyst SD-WAN devices can redistribute route information learned from BGP and OSPF into OMP so that OMP can better choose paths within the overlay network.
When the local site connects to a Layer 3 VPN MPLS WAN cloud, the devices act as an MPLS CE devices and establish a BGP peering session to connect to the PE router in the L3VPN MPLS cloud.
When the devices at a local site do not connect directly to the WAN cloud but are one or more hops from the WAN and connect indirectly through a non-Cisco SD-WAN device, standard routing must be enabled on the devices’ DTLS connections so that they can reach the WAN cloud. Either OSPF or BGP can be the routing protocol.
In both these types of topologies, the BGP or OSPF sessions run over a DTLS connection created on the loopback interface in VRF 0, which is the transport VRF that is responsible for carrying control traffic in the overlay network. The Cisco Catalyst SD-WAN Validator learns about this DTLS connection via the loopback interface and conveys this information to the Cisco Catalyst SD-WAN Controller so that it can track the TLOC-related information. In VRF 0, you also configure the physical interface that connects the Cisco IOS XE Catalyst SD-WAN device to its neighbor—either the PE router in the MPLS case or the hub or next-hop router in the local site—but you do not establish a DTLS tunnel connection on that physical interface.
BGP Community Propagation
Feature Name |
Release Information |
Description |
---|---|---|
Ability to Match and Set Communities during BGP to OMP Redistribution |
Cisco IOS XE Catalyst SD-WAN Release 17.4.1a Cisco vManage Release 20.4.1 |
This feature enhances the implementation of match and set clauses for redistribution of routes from BGP to OMP and vice versa
on Cisco IOS XE Catalyst SD-WAN devices. You can redistribute the routes from a BGP into an OMP routing to allow route traffic to help increase the accessibility
within the network. The
|
BGP Community Propagation |
Cisco IOS XE Catalyst SD-WAN Release 17.3.1a Cisco vManage Release 20.3.1 |
This feature enables propagation of BGP communities between routing protocols during route redistribution. On one node, the OMP redistributes routes from BGP and on the other node, the BGP redistributes routes from OMP. In addition to configurable AS path attribute propagation, there is an option to propagate BGP communities. The BGP community propagation helps in propagating BGP communities between Cisco Catalyst SD-WAN sites, across VPNs using OMP redistribution. To propagate the BGP communities during route redestribution from OMP, use the propagate-community command. |
Starting from Cisco IOS XE Catalyst SD-WAN Release 17.3.1a, the community propagation feature is supported. Without this option, no BGP communities are sent to the BGP neighbor, even if they are attached. With this feature, the Cisco IOS XE Catalyst SD-WAN device can start propagating the communities attached to the BGP entries to the neighbor. The BGP overlay is migrated to a Cisco Catalyst SD-WAN overlay where BGP route attributes are propagated between Cisco Catalyst SD-WAN sites across VPNs. For more information on propagate-community command, refer propagate-community.
Starting from Cisco IOS XE Catalyst SD-WAN Release 17.4.1a, you can manipulate communities when propagating communities from BGP to OMP and back from OMP to BGP using the route-map
command. It defines the conditions for redistributing routes from one routing protocol into another routing protocol. Each
route-map
command has a list of match
and set
commands associated with it. The match
commands specify the match communities
, the conditions under which redistribution is allowed. The set
commands specify the set communities
, the particular redistribution actions to perform if the criteria enforced by the match
commands are met. For more information on the commands, refer Command Reference Guide.
OSPFv3
Feature Name |
Release Information |
Description |
---|---|---|
OSPFv3 Support on Cisco IOS XE Catalyst SD-WAN Devices |
Cisco IOS XE Catalyst SD-WAN Release 17.3.2 Cisco vManage Release 20.3.1 |
Open Shortest Path First version 3 (OSPFv3) is an IPv4 and IPv6 link-state routing protocol that supports IPv6 and IPv4 unicast address families. |
OSPFv3 is a routing protocol for IPv4 and IPv6 address families. It is a link-state protocol that makes its routing decisions based on the states of the links that connect source and destination machines. The state of a link is a description of that interface and its relationship to its neighboring networking devices. The interface information includes the IPv6 prefix of the interface, the network mask, the type of network it is connected to, the devices connected to that network, and so on. This information is propagated in various type of link-state advertisements (LSAs).
Much of OSPFv3 is the same as in OSPF version 2. OSPFv3, which is described in RFC 5340, expands on OSPF version 2 to provide support for IPv6 routing prefixes and the larger size of IPv6 addresses.
For address family IPv6, OSPFv3 routes are referred to OSPF routes and OSPFv3 internal routes (intra-area and inter-area) are implicitly advertised to OMP. OSPFv3 external routes (both AS-External and NSSA) can be explicitly advertised in OMP using the advertise OSPF external configuration. This is consistent with OSPF routes in address family IPv4 where OSPF internal routes are implicitly advertised in OMP. Similarly, OSPF external routes can be explicitly advertised to OMP using the advertise OSPF external configuration.
For address family IPv4, OSPFv3 routes are referred to as OSPFv3 routes and OSPFv3 internal routes are not implicitly advertised in OMP. All OSPFv3 IPv4 routes can be advertised in OMP using the advertise OSPFv3 configuration. OSPFv3 integration in controller mode is not supported.
EIGRP
Cisco EIGRP (Enhanced Interior Gateway Routing Protocol) is a Cisco proprietary routing protocol. It is an open-standard Interior Gateway Protocol (IGP). EIGRP is an enhancement to the original Interior Gateway Routing Protocol (IGRP developed) by Cisco. EIGRP does not fully update if there are no changes in the network. This reduces the flooding activities in other IGPs. It also can use both equal cost and unequal cost paths, which is unique among IGPs.
EIGRP is supported only on Cisco IOS XE Catalyst SD-WAN devices.
See Introduction to EIGRP for more information in EIGRP.
Benefits of EIGRP
-
Increased network width from 15 to 100 hops
-
Fast convergence
-
Incremental updates, minimizing bandwidth
-
Protocol-independent neighbor discovery
-
Easy scaling
Limitations and Restrictions
-
EIGRP is not supported on the transport side network on Cisco IOS XE Catalyst SD-WAN devices.
-
EIGRP route match is not supported in Cisco SD-WAN Controller centralized control policy.
Routing Information Protocol (RIP)
Feature Name |
Release Information |
Description |
---|---|---|
RIPv2 Support on Cisco IOS XE Catalyst SD-WAN Devices |
Cisco IOS XE Catalyst SD-WAN Release 17.7.1a Cisco vManage Release 20.7.1 Cisco SD-WAN Release 20.7.1 |
This feature enables you to configure RIPv2 on Cisco IOS XE Catalyst SD-WAN devices. Routers redistribute RIPv2 routes to Overlay Management Protocol (OMP) for advertisement in the Cisco Catalyst SD-WAN overlay, and to Open Shortest Path First version 3 (OSPFv3) for service-side routing. |
RIPng (IPv6) Support on Cisco IOS XE Catalyst SD-WAN Devices |
Cisco IOS XE Catalyst SD-WAN Release 17.8.1a Cisco vManage Release 20.8.1 Cisco SD-WAN Release 20.8.1 |
This feature adds support for IPv6 addresses and prefixes on Cisco IOS XE Catalyst SD-WAN devices. It also supports redistribution of connect, static, Overlay Management Protocol (OMP), and Open Shortest Path First (OSPF) routes into Routing Information Protocol next generation (RIPng). |
Information About Routing Information Protocol Support
The Routing Information Protocol (RIP) uses broadcast or multicast User Datagram Protocol (UDP) data packets to exchange routing information. RIP is a commonly used routing protocol in small to medium TCP/IP networks. RIP uses a distance-vector algorithm to calculate routes. Cisco IOS software sends routing information updates every 30 seconds, which is termed as advertising. RIP sends routing-update messages at regular intervals, and when the network topology changes.
RIPv2 (RIP for IPv4)
In the Cisco IOS software implementation of RIP Version 2 (RIPv2), each RIP process maintains a local database. The RIP local database contains a set of best-cost RIP routes that are learned from all the networking devices neighboring to RIP-enabled routers. Route redistribution allows routes to be specified by a prefix, using a route map and prefix list.
The Cisco implementation of RIPv2 supports plain text and message digest algorithm 5 (MD5) authentication, route summarization, classless interdomain routing (CIDR), and variable-length subnet masks (VLSMs). If you are sending and receiving RIPv2 packets, we recommend that you enable RIP authentication on an interface because RIPv1 does not support authentication. Plain text authentication is the default authentication in every RIPv2 packet.
By default, the software receives RIP Version 1 (RIPv1) and RIPv2 packets, but sends only RIPv1 packets. You can configure the software to receive and send only RIPv1 packets. Alternatively, you can configure the software to receive and send only RIPv2 packets. To override the default behavior, you can configure the RIP version that an interface sends. Similarly, you can also control how packets that are received from an interface are processed. RIP v2 is supported on both service side and transport side.
Note |
For network configuration, we recommend that you use Classful IP Network ID Addressing. |
See Configure Routing Information Protocol Using the CLI for more details on configurations using the CLI.
RIPng (RIP for IPv6)
Routing Information Protocol next generation (RIPng) is a UDP-based protocol for communicating routing information that is used to compute routes through IPv6 networks. RIP enhancements for IPv6, which are detailed in RFC 2080, include support for IPv6 addresses and prefixes.
RIPng as an Interior Gateway Protocol (IGP) supports redistribution of the following:
-
OMP routes into RIP
-
RIP routes into OMP
-
RIP routes into OSPFv3
-
OSPFv3 routes into RIP
-
Static routes into RIP
-
RIP routes into static
-
Connect routes into RIP
-
RIP routes into connect
Each router that implements RIPng requires a routing table containing the following fields:
-
The IPv6 prefix of the destination.
-
Metric: Total cost of the metric advertised for the address.
-
Route Tag: A route attribute that must be advertised and redistributed with the route.
-
Next-hop IPv6 address of the destination.
-
Various timers associated with the routes.
When not in Virtual Routing and Forwarding (VRF) mode, every IPv6 RIPng process and the configuration that is associated with it keeps all the routes in the same routing table. The IPv6 RIPng VRF-aware support enables isolation, modularity, and potential performance improvement by reducing the number of routes stored in a single routing table. It also allows a network administrator to create different RIP routing tables and share the same protocol configuration that is stored in a single RIP protocol configuration block.
RIPng in large networks is prone to routing loops, making the traffic take a longer path. To avoid route looping, RIP and RIPng routes are identified using the well-known OMP RIP tag.
The following figure illustrates the RIPv2 and RIPng OMP route tagging process:
-
Core-Router1 advertises RIPv2 and RIPng routes to Site1.
As a general rule, the RIPv2 and RIPng routes have a default administrative distance of 120. The default administrative distance for OMP routes is 251.
-
The RIPv2 and RIPng route is redistributed and advertised in OMP.
-
The Cisco Catalyst SD-WAN Controller advertises an OMP route to the other branch.
-
Site-2 Edge1 router adds an OMP route tag of a unique value of 44270, and redistributes the OMP-learned route into RIPv2 and RIPng.
-
When the Site-2 Edge2 router receives this route with the tag 44270, it will not install this route because it is already learning a route through OMP, which has AD 251.
If the OMP route is withdrawn, the Site-2 Edge2 router installs the route, which is learned through the RIPv2 and RIPng protocol through service-side VPN with the tag 44270, into the routing table with an administrative distance of 252 (one value higher than that of OMP).
Additionally, a Cisco Catalyst SD-WAN tagged route will not be readvertised in OMP when the RIPv2 and RIPng route is redistributed to OMP.
See Configure RIPng Using the CLI for more details on RIPng configurations using the CLI.
Prerequisites for Using Routing Information Protocol
-
Version 2 must be configured to send and receive only RIPv2 packets. By default, RIP Version 1 (RIPv1) and RIP Version 2 (RIPv2) packets are received, but only RIPv1 packets are sent.
Restrictions for Using Routing Information Protocol
RIPv2 (IPv4)
RIP uses hop count as the metric to rate the value of different routes. Hop count is the number of devices that can be traversed in a route. A directly connected network has a metric of zero; an unreachable network has a metric of 16. This limited metric range makes RIP unsuitable for large networks.
RIPng (IPv6)
-
Only the sdwan keyword can be used to configure the IPv6 RIP routing process name (ripng-instance ) in the configuration commands.
-
VRF-aware support in IPv6 RIP allows only one RIP instance at a given time. More than one RIP instance is not allowed.
-
You can configure RIPng on only GigabitEthernet, TenGigabitEthernet, and VLAN interfaces.