Contents

Introduction

Prerequisites

Requirements

Components Used

Background Information

Configuration

Verify

Troubleshoot

Solution 1

Overlay-AS Case 1

Overlay-AS Case 2

Solution 2

SoO Loop Prevention Explanation

Related Information

Introduction

This document describes how to avoid a routing loop in SD-WAN fabric when Border Gateway Protocol (BGP) routing and Site of Origin (SoO) is used.

Prerequisites

Requirements

Cisco recommends that you have knowledge of these topics:

- Basic understanding of Overlay Management Protocol (OMP)

- Basic understanding of BGP

- SD-WAN components and interaction between them

Components Used

The information in this document is based on these software and hardware versions:

- 3 Cisco IOS® XE CSR1000v routers with Software Release 17.2.1v that run in controller mode (SD-WAN)

- 2 Cisco IOS XE CSR1000v routers with Software Release 16.7.3

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, ensure that you understand the potential impact of any command.

Background Information

For the purpose of this document, this topology is used:

Topology

R1 and R2 are generic Cisco IOS XE routers (or any other router capable of running BGPv4). cE1, cE2, and cE3 run Cisco IOS XE in controller (SD-WAN) mode. Here you can find a summary of assigned site-id and system-ip parameters to each SD-WAN router:

SD-WAN router

site-id

system-ip

cE1

214

192.168.30.214

cE2

215

192.168.30.215

cE3

216

192.168.30.216

Here is a set of events that took place initially:

1. R1 and R2 establish eBGP peering correspondingly with cE1, cE2, and cE3. cE1 and cE2 establish iBGP peering.

2. R2 originates BGP route 10.1.1.0/24 and advertises it via eBGP to cE3.

3. cE3 receives this BGP route on the service side in the VRF 1 address family and then redistributes this route into OMP.

4. cE3 advertises the 10.1.1.0/24 OMP route to the SD-WAN overlay (vSmart controllers are responsible for routing information dissemination via the OMP protocol to all other Edge routers joined to the SD-WAN overlay).

5. cE1 and cE2 receive the OMP route and redistribute it back via eBGP in VRF 1 to R1.

Configuration

Here is the relevant configuration of cE1. Note that send-comminity is not configured for neighbor 192.168.160.215:

router bgp 65401

bgp log-neighbor-changes

distance bgp 20 200 20

!

address-family ipv4 vrf 1

redistribute omp

propagate-aspath

neighbor 192.168.140.10 remote-as 65300

neighbor 192.168.140.10 activate

neighbor 192.168.140.10 send-community both

neighbor 192.168.160.215 remote-as 65400

neighbor 192.168.160.215 activate

exit-address-family

!

sdwan

omp

no shutdown

send-path-limit  4

ecmp-limit       4

graceful-restart

no as-dot-notation

timers

holdtime               60

advertisement-interval 1

graceful-restart-timer 43200

eor-timer              300

exit

address-family ipv4 vrf 1

advertise bgp

!

address-family ipv4

advertise connected

advertise static

!

address-family ipv6

advertise connected

advertise static

cE2:

router bgp 65401

bgp log-neighbor-changes

distance bgp 20 200 20

!

address-family ipv4 vrf 1

redistribute omp

propagate-aspath

neighbor 192.168.150.10 remote-as 65300

neighbor 192.168.150.10 activate

neighbor 192.168.150.10 send-community both

neighbor 192.168.160.214 remote-as 65401

neighbor 192.168.160.214 activate

neighbor 192.168.160.214 send-community both

exit-address-family

!

sdwan

omp

no shutdown

send-path-limit  4

ecmp-limit       4

graceful-restart

no as-dot-notation

timers

holdtime               60

advertisement-interval 1

graceful-restart-timer 43200

eor-timer              300

exit

address-family ipv4 vrf 1

advertise bgp

!

address-family ipv4

advertise connected

advertise static

!

address-family ipv6

advertise connected

advertise static

cE3:

router bgp 65401

bgp log-neighbor-changes

timers bgp 5 15

!

address-family ipv4 vrf 1

redistribute omp

propagate-aspath

neighbor 192.168.60.11 remote-as 65500

neighbor 192.168.60.11 activate

exit-address-family

!

sdwan

omp

no shutdown

send-path-limit  4

ecmp-limit       4

graceful-restart

no as-dot-notation

timers

holdtime               60

advertisement-interval 1

graceful-restart-timer 43200

eor-timer              300

exit

address-family ipv4 vrf 1

advertise bgp

!

address-family ipv4

advertise connected

advertise static

!

address-family ipv6

advertise connected

advertise static

!

Verify

1. In the initial state, the route is advertised from cE3 and learned by cE1 and cE2 via OMP. Both redistribute the route to BGP and announce to each other and to R1:

cE1#

show bgp vpnv4 unicast vrf 1 10.1.1.1/24

BGP routing table entry for 1:1:10.1.1.1/24, version 342041

Paths: (2 available, best #2, table 1)

Advertised to update-groups:

4          5

Refresh Epoch 1

65500

192.168.160.215 (via vrf 1) from 192.168.160.215 (192.168.109.215)

Origin incomplete, metric 1000, localpref 50, valid, internal

Extended Community: SoO:0:215 RT:1:1

rx pathid: 0, tx pathid: 0

Updated on Aug 21 2020 11:23:32 GMT

Refresh Epoch 1

65500

192.168.30.216 (via default) from 0.0.0.0 (192.168.109.214)

Origin incomplete, metric 1000, localpref 50, valid, sourced, best

Extended Community: SoO:0:214 RT:1:1

rx pathid: 0, tx pathid: 0x0

Updated on Aug 21 2020 11:23:32 GMT

cE2#

show bgp vpnv4 unicast vrf 1 10.1.1.1/24

BGP routing table entry for 1:1:10.1.1.1/24, version 327810

Paths: (2 available, best #2, table 1)

Advertised to update-groups:

5          6

Refresh Epoch 1

65500

192.168.160.214 (via vrf 1) from 192.168.160.214 (192.168.109.214)

Origin incomplete, metric 1000, localpref 50, valid, internal

Extended Community: RT:1:1

rx pathid: 0, tx pathid: 0

Updated on Aug 21 2020 11:23:32 GMT

Refresh Epoch 1

65500

192.168.30.216 (via default) from 0.0.0.0 (192.168.109.215)

Origin incomplete, metric 1000, localpref 50, valid, sourced, best

Extended Community: SoO:0:215 RT:1:1

rx pathid: 0, tx pathid: 0x0

Updated on Aug 21 2020 11:23:32 GMT

2. The WAN interface is disconnected or connectivity to SD-WAN fabric is lost on cE2, hence OMP peers (vSmart connections) go down. Only one route remains learned from iBGP:

ce2(config)#

interface GigabitEthernet 2

ce2(config-if)#

shutdown

ce2(config-if)#

end

Uncommitted changes found, commit them? [yes/no/CANCEL] yes

Commit complete.

ce2#

show bgp vpnv4 unicast vrf 1 10.1.1.1/24

BGP routing table entry for 1:1:10.1.1.1/24, version 345276

Paths: (1 available, best #1, table 1)

Advertised to update-groups:

6

Refresh Epoch 1

65500

192.168.160.214 (via vrf 1) from 192.168.160.214 (192.168.109.214)

Origin incomplete, metric 1000, localpref 50, valid, internal, best

Extended Community: RT:1:1

rx pathid: 0, tx pathid: 0x0

Updated on Aug 21 2020 11:23:32 GMT

cE1 still prefers the route via OMP (this is the only route that remains) originated by cE3:

ce1#

show bgp vpnv4 unicast vrf 1 10.1.1.1/24

BGP routing table entry for 1:1:10.1.1.1/24, version 342041

Paths: (1 available, best #1, table 1)

Advertised to update-groups:

4          5

Refresh Epoch 1

65500

192.168.30.216 (via default) from 0.0.0.0 (192.168.109.214)

Origin incomplete, metric 1000, localpref 50, valid, sourced, best

Extended Community: SoO:0:214 RT:1:1

rx pathid: 0, tx pathid: 0x0

Updated on Aug 21 2020 11:23:32 GMT

3. Connectivity on the WAN interface of cE2 is established again. The route is still preferred from cE1 via iBGP because of better Administrative Distance (AD).

ce2(config)#

interface GigabitEthernet 2

ce2(config-if)#

no shutdown

ce2(config-if)#

end

Uncommitted changes found, commit them? [yes/no/CANCEL] yes

Commit complete.

ce2#

show bgp vpnv4 unicast vrf 1 10.1.1.1/24

BGP routing table entry for 1:1:10.1.1.1/24, version 345276

Paths: (1 available, best #1, table 1)

Advertised to update-groups:

6

Refresh Epoch 1

65500

192.168.160.214 (via vrf 1) from 192.168.160.214 (192.168.109.214)

Origin incomplete, metric 1000, localpref 50, valid, internal, best

Extended Community: RT:1:1

rx pathid: 0, tx pathid: 0x0

Updated on Aug 21 2020 11:23:32 GMT

cE1 still prefers the route via OMP originated by cE3. Keep in mind that cE1 redistributes OMP into BGP:

ce1#

show bgp vpnv4 unicast vrf 1 10.1.1.1/24

BGP routing table entry for 1:1:10.1.1.1/24, version 569358

Paths: (1 available, best #1, table 1)

Advertised to update-groups:

4          5

Refresh Epoch 1

65500

192.168.30.216 (via default) from 0.0.0.0 (192.168.109.214)

Origin incomplete, metric 1000, localpref 50, valid, sourced, best

Extended Community: SoO:0:214 RT:1:1

rx pathid: 0, tx pathid: 0x0

Updated on Aug 21 2020 15:13:09 GMT

4. Something happens with cE3 connectivity to R2. To test, the interface is shut down, and the R2 BGP peer is lost:

ce3(config)#

interface GigabitEthernet 6

ce3(config-if)#

shutdown

ce3(config-if)#

commit

5. As a result, the routing loop is formed between cE1 and cE2 (cE2 redistributes the route from OMP and advertises to cE1 via BGP, cE1 redistributes BGP to OMP and advertises to cE2):

ce1#

show bgp vpnv4 unicast vrf 1 10.1.1.1/24

BGP routing table entry for 1:1:10.1.1.1/24, version 732548

Paths: (1 available, best #1, table 1)

Advertised to update-groups:

5

Refresh Epoch 1

65500

192.168.160.215 (via vrf 1) from 192.168.160.215 (192.168.109.215)

Origin incomplete, metric 1000, localpref 50, valid, internal, best

Extended Community: SoO:0:215 RT:1:1

rx pathid: 0, tx pathid: 0x0

Updated on Aug 21 2020 15:38:47 GMT

ce2#

show bgp vpnv4 unicast vrf 1 10.1.1.1/24

BGP routing table entry for 1:1:10.1.1.1/24, version 639650

Paths: (1 available, best #1, table 1)

Advertised to update-groups:

5          6

Refresh Epoch 1

65500

192.168.30.214 (via default) from 0.0.0.0 (192.168.109.215)

Origin incomplete, metric 1000, localpref 50, valid, sourced, best

Extended Community: SoO:0:215 RT:1:1

rx pathid: 1, tx pathid: 0x0

Updated on Aug 21 2020 15:38:47 GMT

Troubleshoot

There are two possible solutions.

Solution 1

Configure overlay-as for OMP. Then some Autonomous System (AS) number is assigned to the OMP overlay itself. For example:

config-transaction

sdwan

omp

overlay-as 64512

exit

By default, OMP is transparent to BGP even if propagate-aspath is configured. overlay-as is a feature that prepends AS specified as a parameter of this command to the BGP AS_PATH attribute of routes exported from OMP to BGP. If you configure the same overlay AS number on multiple devices in the overlay network, all these devices are considered to be part of the same AS. As a result, they do not forward any routes that contain the overlay AS number, hence the routing loop is prevented.

Keep in mind that overlay-as and propagate-aspath are dependent on each other. This feature is discussed in detail.

There are two cases that exist.

Overlay-AS Case 1

overlay-as configured on the global level under sdwan omp section and propagate-aspath is not configured (rest configuration is the same as described initially: advertise bgp is enabled under omp address-family ipv4 vrf 1 section, redistribute omp configured under router bgp <AS> address-family ipv4 vrf 1 section).

overlay-as 64512, configured on cE1/cE2 and cE3.

Topology for overlay-as demonstration

For the purpose of demonstration, BGP AS on cE1, cE2, and cE3 changed.

R1 - cE1/cE2 still peer via eBGP, AS 65300 and 65401 are used respectively.

cE3 - R2 still peer via eBGP, AS 65402 and 65500 are used respectively.

R1 sends route (for example, 192.168.41.11/32) to cE1/cE2. cE1/cE2 redistributes this route into OMP, without any AS_PATH attribute.

cE3 receives it and advertises it into BGP towards R2, only with its own AS (normal eBGP behavior).

Route route1 on R2 has AS_PATH: 65402.

R2#

sh ip bgp | i 192.168.41.11/32

*>   192.168.41.11/32 192.168.60.216        1000             0 65402 ?

Overlay-AS Case 2

propagate-aspath configured under router bgp section for the particular service side VPN (address-family ipv4 vrf 1). Here are sub-cases as well.

Case 2.1. With overlay-as enabled on cE3, propagate-aspath is also enabled under router bgp 65401 address-family ipv4 vrf 1 on cE1/cE2.

R1 sends route route1 to cE1/cE2. cE1/cE2 redistributes this route into OMP with an as-path that comes from the R1 site.

OMP route on vSmart has AS-Path: 65300.

vsmart1#

show omp routes vpn 1 192.168.41.11/32 | nomore | exclude not\ set

---------------------------------------------------

omp route entries for vpn 1 route 192.168.41.11/32

---------------------------------------------------

RECEIVED FROM:

peer            192.168.30.214

path-id         81

label           1001

status          C,R

Attributes:

originator       192.168.30.214

type             installed

tloc             192.168.30.214, biz-internet, ipsec

overlay-id        1

site-id          25

origin-proto     eBGP

origin-metric    0

as-path          "65300"

RECEIVED FROM:

peer            192.168.30.215

path-id         68

label           1002

status          C,R

Attributes:

originator       192.168.30.215

type             installed

tloc             192.168.30.215, biz-internet, ipsec

overlay-id        1

site-id          25

origin-proto     eBGP

origin-metric    0

as-path          "65300"

Case 2.1.a. With propagate-aspath disabled on cE3, cE3 receives it as an OMP route and advertises it into BGP, ignores any as-path attribute, overlays as, towards R2, and adds only its own BGP AS (normal eBGP behavior).

Route route1 on R2 AS-path: 65402.

R2#

sh ip bgp | i 192.168.41.11/32

*>   192.168.41.11/32 192.168.60.216        1000             0 65402 ?

Case 2.1.b. With propagate-aspath enabled on cE3, cE3 receives it as an OMP route and advertises it into BGP, prepends the received as-path attribute, towards R2 then adds the Overlay-AS followed by its own BGP AS.

Route route1 on R2 AS-path: 65402 64512 65300.

R2#

sh ip bgp | i 192.168.41.11/32

*>   192.168.41.11/32 192.168.60.216        1000             0 65402 64512 65300 ?

Case 2.1.c. With propagate-aspath disabled on cE1/cE2, cE3 receives it as an OMP route without any as-path attribute and advertises it into BGP, towards R2, prepends the Overlay-AS and adds only its own BGP AS.

Route route1 on R2 AS-path: 6540264512.

R2#

sh ip bgp | i 192.168.41.11/32

*>   192.168.41.11/32 192.168.60.216        1000             0 65402 64512 ?

Case 2.2. Without overlay-as configured on cE3, propagate-aspath is enabled under router bgp 65401 address-family ipv4 vrf 1 on cE1/cE2.

Case 2.2.a. With propagate-aspath disabled on cE3 only, cE3 receives it as an OMP route and advertises it into BGP, ignoring any AS_PATH attribute, towards R2, adds its own BGP AS (normal eBGP behavior).

Route route1 on R2 AS-path: 65402.

R2#

sh ip bgp | i 192.168.41.11/32

*>   192.168.41.11/32 192.168.60.216        1000             0 65402 ?

Case 2.2.b. When propagate-aspath is enabled on cE3, cE3 receives it as an OMP route and advertises it into BGP, prepends the received AS_PATH attribute, towards R2 then adds its own AS.

Route route1 on R2 AS-path: 6540265300.

R2#

sh ip bgp | i 192.168.41.11/32

*>   192.168.41.11/32 192.168.60.216        1000             0 65402 65300 ?

Note: When you send the AS-Path attribute into OMP, the Edge router does not add its own AS (as demonstrated in the article vEdge Does Not Advertise Its Own AS When BGP Routes Are Advertised Into OMP). If the remote Edge router receives an OMP route with its own AS in the AS_PATH attribute, it does not perform loop detection and it sends the route with the received AS path to the router on the service side.

Solution 2

Configure the same site-id on routers cE1 and cE2. Although the vSmart advertises routes back to the site with the same site-id as in the route itself, since the originator attribute of the route is different, loop prevention is not triggered, but the control plane routing loop does not form because the OMP route is not installed into the RIB. This is because the OMP route stays in the Inv,U (Invalid,Unresolved) state. By default, data plane tunnels cannot be established between sites that have the same site-id unless allow-same-site-tunnels is configured. If the data plane tunnel BFD session is in the down state, TLOC remains unresolved. In the example here, site-id 214215 was configured on both routers ce1 and ce2. Route 10.0.0.2/32 advertised by cE2 and cE1 does not install it into the routing table because no data plane sessions exist between cE1 and cE2:

ce1#

show sdwan omp route 10.0.0.2/32 det | exc not set

---------------------------------------------------

omp route entries for vpn 3 route 10.0.0.2/32

---------------------------------------------------

RECEIVED FROM:

peer            192.168.30.113

path-id         3

label           1004

status          Inv,U

Attributes:

originator       192.168.30.215

type             installed

tloc             192.168.30.215, mpls, ipsec

overlay-id        1

site-id          214215

origin-proto     connected

origin-metric    0

RECEIVED FROM:

peer            192.168.30.113

path-id         4

label           1004

status          Inv,U

loss-reason     tloc-id

lost-to-peer    192.168.30.113

lost-to-path-id 3

Attributes:

originator       192.168.30.215

type             installed

tloc             192.168.30.215, biz-internet, ipsec

overlay-id        1

site-id          214215

origin-proto     connected

origin-metric    0

ce1#

show sdwan omp tlocs "ip 192.168.30.215" | exclude not set

---------------------------------------------------

tloc entries for 192.168.30.215

mpls

ipsec

---------------------------------------------------

RECEIVED FROM:

peer            192.168.30.113

status          C,I,R

Attributes:

attribute-type    installed

encap-proto       0

encap-spi         256

encap-auth        sha1-hmac,ah-sha1-hmac

encap-encrypt     aes256

public-ip         192.168.110.215

public-port       12347

private-ip        192.168.110.215

private-port      12347

public-ip         ::

public-port       0

private-ip        ::

private-port      0

bfd-status        down

site-id           214215

preference        0

weight            1

version           3

gen-id             0x80000026

carrier           default

restrict          0

groups            [ 0 ]

bandwidth         0

qos-group         default-group

---------------------------------------------------

tloc entries for 192.168.30.215

biz-internet

ipsec

---------------------------------------------------

RECEIVED FROM:

peer            192.168.30.113

status          C,I,R

Attributes:

attribute-type    installed

encap-proto       0

encap-spi         256

encap-auth        sha1-hmac,ah-sha1-hmac

encap-encrypt     aes256

public-ip         192.168.109.215

public-port       12347

private-ip        192.168.109.215

private-port      12347

public-ip         ::

public-port       0

private-ip        ::

private-port      0

bfd-status        down

site-id           214215

preference        0

weight            1

version           3

gen-id             0x80000026

carrier           default

restrict          0

groups            [ 0 ]

bandwidth         0

qos-group         default-group

ce1#

You can check this command on the vSmart controller in order to understand which routes receive the particular prefix (see "ADVERTISED TO" section):

vsmart1#

show omp routes 10.1.1.0/24 detail | nomore | exclude not\ set

---------------------------------------------------

omp route entries for vpn 1 route 10.1.1.0/24

---------------------------------------------------

RECEIVED FROM:

peer            192.168.30.216

path-id         68

label           1002

status          C,R

Attributes:

originator       192.168.30.216

type             installed

tloc             192.168.30.216, biz-internet, ipsec

overlay-id        1

site-id          216

origin-proto     eBGP

origin-metric    0

as-path          65500

ADVERTISED TO:

peer    192.168.30.214

Attributes:

originator       192.168.30.216

label            1002

path-id          5525

tloc             192.168.30.216, biz-internet, ipsec

site-id          216

overlay-id        1

origin-proto     eBGP

origin-metric    0

as-path          65500

ADVERTISED TO:

peer    192.168.30.215

Attributes:

originator       192.168.30.216

label            1002

path-id          5287

tloc             192.168.30.216, biz-internet, ipsec

site-id          216

overlay-id        1

origin-proto     eBGP

origin-metric    0

as-path          65500

Thesite-id is also preserved as BGP site-of-origin (SoO) extended community attribute (you can notice SoO:0:<site-id> in the previous outputs). That is used to identify routes that have originated from a site so that the re-advertisement of that prefix back can be prevented. For this to function correctly, routers must send extended communities. Configure cE1 to send extended communities to router cE2:

router bgp 65401

address-family ipv4 vrf 1

neighbor 192.168.160.215 send-community both

SoO Loop Prevention Explanation

For the case where two routers at the same site are iBGP neighbors, SD-WAN has a built-in loop-prevention mechanism in order to prevent a routing loop from OMP to BGP and back from BGP to OMP. In order to demonstrate this, the topology was slightly updated and the same site-id 214215 was configured on both routers that run BGP AS65400 (cE1/cE2). In this example, a 10.1.1.0/24 prefix is advertised into OMP from the remote site (cE3) and learned in OMP at Site 214215 (cE1-cE2).

Topology for SoO demontration

In order to accomplish loop-prevention, the BGP extended community SoO is used to show which site originated the prefix. This community is added to a prefix when it is redistributed from OMP into BGP.

The send-community <both|extended> command must be configured on the neighbor statement in both devices as shown, in order for this functionality to work correctly.

cEdge1#

show run | sec router bgp

router bgp 65400

bgp log-neighbor-changes

!

address-family ipv4 vrf 1

redistribute omp

neighbor 192.168.160.215 remote-as 65400

neighbor 192.168.160.215 activate

neighbor 192.168.160.215 send-community both

exit-address-family

cEdge2#

show run | sec router bgp

router bgp 65400

bgp log-neighbor-changes

!

address-family ipv4 vrf 1

neighbor 192.168.160.214 remote-as 65400

neighbor 192.168.160.214 activate

neighbor 192.168.160.214 send-community both

exit-address-family

The extended community can be seen with the output of show bgp vpnv4 unicast vrf 1 <prefix> from either the advertising or receiving site.

Example

cEdge1#

show bgp vpnv4 unicast vrf 1 10.1.1.1

BGP routing table entry for 1:10:10.1.1.1/24, version 4

Paths: (1 available, best #1, table 1)

Advertised to update-groups:

1

Refresh Epoch 1

Local

192.168.30.215 (via default) from 0.0.0.0 (192.168.109.215)

Origin incomplete, metric 1000, localpref 50, valid, sourced, best

Extended Community: SoO:0:214215 RT:1:1

rx pathid: 0, tx pathid: 0x0

Updated on Jul 5 2152 23:30:55 UTC

On the router which advertises the prefix from OMP into BGP (cEdge1 in this example), only the OMP route must be present in the RIB.

Example

cEdge1#

show ip route vrf 1 10.1.1.1

Routing Table: 1

Routing entry for 10.1.1.1/32

Known via "omp", distance 251, metric 0, type omp

Redistributing via bgp 65400

Advertised by bgp 65400

Last update from 192.168.30.215 on Sdwan-system-intf, 15:59:54 ago

Routing Descriptor Blocks:

* 192.168.30.215 (default), from 192.168.30.215, 15:59:54 ago, via Sdwan-system-intf

Route metric is 0, traffic share count is 1

However, it can happen that a race condition occur on the second router which receives the advertised prefix and causes the BGP route to get installed in the RIB prior to the OMP route getting learned.

On cEdge2, the output of sh bpg vpnv4 unicast vrf 1 <prefix> shows these:

1. Not advertised to any peer.

2. Extended Community includes the site-id 214215 which is the same site this router is at.

Example

cEdge2#

show bgp vpnv4 unicast vrf 1 10.1.1.1

BGP routing table entry for 1:1:10.1.1.1/24, version 32

Paths: (1 available, best #1, table 1)

Not advertised to any peer

Refresh Epoch 1

Local

192.168.160.214 (via vrf 1) from 192.168.160.214 (192.168.54.11)

Origin incomplete, metric 1000, localpref 50, valid, internal, best

Extended Community: SoO:0:214215 RT:65512:10

rx pathid: 0, tx pathid: 0x0

Updated on Jul 6 2152 17:26:19 UTC

On cEdge2, the output of sh ip route vrf <vrf_number> <prefix> shows these:

1. The flag “SDWAN Down” is seen to show that this has been detected to have originated from the same site.

2. The administrative distance of the route is 252 (higher than OMP and different than the expected iBGP AD 200).

Example

cEdge2#

show ip route vrf 1 10.1.1.1

Routing Table: 1

Routing entry for 10.1.1.0/24

Known via "bgp 65400",

distance 252

, metric 1000, type internal

Redistributing via omp

Last update from 192.168.160.214 00:15:13 ago

Routing Descriptor Blocks:

* 192.168.160.214, from 192.168.160.214, 00:15:13 ago

opaque_ptr 0x7F9DD0B86818

SDWAN Down

Route metric is 1000, traffic share count is 1

AS Hops 0

MPLS label: none

When a site router detects that a BGP learned route originates from the same site-id, the route is not advertised back into OMP.

Related Information

- vEdge Does Not Advertise Its Own AS When BGP Routes Are Advertised Into OMP

- Cisco SD-WAN Routing Configuration Guide, Cisco IOS XE Release 17.x - Configure OMP Using CLI

- IP Routing: BGP Configuration Guide

- Configuring Unicast Overlay Routing

- Cisco SD-WAN Command Reference - overlay-as

- Cisco Technical Support & Downloads