Which OMP Route Wins From the Same SD-WAN Device?
Configure OMP
Answer
Correct answer: D — when the OMP route is valid and learned from the same Cisco SD-WAN device at location S4406T9E02F15, the route with the lower administrative distance is selected.
Which OMP route is selected if it was learned from the same Cisco SD-WAN device at location S4406T9E02F15?
Community Insight
The test is whether you know the same-device branch of the OMP path-selection algorithm, and the trap is reflexively choosing the higher OMP route preference instead of the administrative-distance tie-breaker that applies only on vEdge routers in that specific case.
This 300-415 question probes the Cisco Catalyst SD-WAN OMP best-path tie-breaker that applies when competing routes to the same destination were learned from the one vEdge/Catalyst 8000 device at location S4406T9E02F15. Because device-identifying criteria cannot separate the routes, the documentation directs selection of the OMP route with the lower administrative distance.
Most learners pick B, the higher OMP route preference value, because eVo3000's popular step list puts "prefer highest route preference" early; but administrative distance is evaluated before route preference, and it is the explicit tie-breaker Cisco documents for routes learned from the same device.
Community Discussion (20 comments)
cc37f90
👍 1
Selected: B
correct is B
d656971
👍 2
Selected: B
Cant be C, as it's the same router. Cant be D as it's only OMP. That leaves A or B, and B makes more sense.
mikidvd51
👍 1
Vague question. Such questions cannot be on paid exams.
Loi2525
👍 2
Selected: D
See Shahansa's comment for the link, answer is verified.
Shahansa
👍 5
It is D https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/bridging-routing-segmentation-qos/vedge/bridging-routing-segmentation-qos-book/unicast-overlay-routing.html#:~:text=If%20the%20OMP%20route%20is,higher%20OMP%20route%20preference%20value.
Seba_o_s
👍 1
Selected: C
The AD and the preference should be the same, it says nothing that changes were made to those values. So there are the values that are different such as the metric and the system IP, it does not say anything about the metric either so they should be the same therefore yes or yes the system IP should be different and the one with a higher value has greater preference
Seba_o_s
👍 1
it is a choice between the same source protocol (OMP), therefore they have the same AD, I discard answer D for me.
Knowledge33
👍 2
Selected: D
https://www.networkacademy.io/ccie-enterprise/sdwan/omp-best-path-selection
Outlaw_87
👍 3
Selected: D
D is correct
Outlaw_87
👍 1
From Official Book (authors Jason, Dana, Dustin and John): Chapter 3 - Control Plane and Data Plane Operations Path Selection: The best-path selection occurs in the following order: 1. Valid OMP route 2. Locally sourced OMP route 3. Lower administrative distance 4. Higher OMP Preference 5. Higher TLOC Preference 6. Prefer Origin 7.
Outlaw_87
👍 1
sorry for typo 7. Lowest Origin metric 8. Highest System IP 9. Highest TLOC private address So, I'll go with D.
Aldebeer
👍 1
B is the correct answer according to me
PepaZdepa33
👍 3
Selected: D
1) Prefer ACTIVE routes over STALE routes. 2) Select routes that are Valid. 3) Prefer routes with lower administrative distance (AD) (on vEdge only). AD is a locally-significant value on each router and depends on the OS. 4) Prefer routes with a higher route preference value. By default, all omp routes have 0 preference. 5) Prefer routes with a higher TLOC preference value (on vEdge only). TLOC preference is a parameter in TLOC routes. 6) Compare the origin type 7) Compare the origin metric - prefer lower metric so I would go with D
hamidreza0010
👍 1
Selected: D
D is the correct answer
Roger95
👍 3
Selected: B
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. But this question does not mention about multiple routing protocols from remote site.
sdwanlove
👍 3
Please disregards my previous post. I found this: https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/routing/ios-xe-17/routing-book-xe/m-unicast-routing.html "If the OMP route is valid and if it has been learned from the same Cisco SD-WAN device, select the OMP route with the lower administrative distance." So it should be D.
sdwanlove
👍 1
AD does not take part of OMP as it is no listed here: https://www.cisco.com/c/en/us/support/docs/routers/sd-wan/217479-omp-best-path-selection-peculiarities-an.html So it should be B "route with the higher OMP route preference value"
eVo3000
👍 4
Selected: B
https://www.cisco.com/c/en/us/support/docs/routers/sd-wan/217479-omp-best-path-selection-peculiarities-an.html 1. Route Resolvability Next-hop TLOC is Reachable (data plane BFD session is here) 2. Prefer highest route preference 3. Prefer highest TLOC preference 4. Prefer best origin code (Connected, Static, eBGP, EIGRP Internal, OSPF Intra, OSPF Inter, OSPF External, EIGRP External iBGP, Unknown/Unset 6. Route Source Preference On vSmart: prefer Edge router-sourced route over vSmart-sourced route 5. Prefer OMP Route with lowest origin metric 7. Prefer route received from lowest System-IP 8. Prefer route from highest Private TLOC IP-address originated from the same site-id 9. outbound control policy 10. send-path-limit
Jervv
👍 1
Please confirm if B or D. How can AD be different if it came from the same device?
Neil_Neo234
👍 1
https://www.networkacademy.io/ccie-enterprise/sdwan/omp-best-path-selection Prefer routes with lower administrative distance (AD) (on vEdge only). AD is a locally-significant value on each router and depends on the OS. Different platforms may have different AD values for different protocols. For example, OMP has AD of 250 on vEdges and 251 on cEdges. Additionally, network admins can define floating static routes with various ADs for the same prefix. AD is only compared when the same WAN edge router receives the same site-local prefix from multiple routing protocols. AD is not a parameter in OMP, is not advertised, and does not influence vSmart.
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Expert Analysis
Why the Answer Is Correct
Cisco's unicast overlay routing documentation states verbatim: "If the OMP route is valid and if it has been learned from the same Cisco SD-WAN device, select the OMP route with the lower administrative distance." The algorithm first discards non-active and invalid routes, then — on vEdge platforms — compares administrative distance of routes coming from the same device, and only afterwards proceeds to route preference, TLOC preference, origin metrics, and router ID. Since both candidate routes at location S4406T9E02F15 originate from one identical device, the administrative distance is the deciding attribute, making D correct.Why the Other Options Are Wrong
Option A, the lower origin metric, and the origin-code comparison sit much later in the sequence and are reached only after administrative distance, route preference, and TLOC preference have failed to produce a winner; moreover all OMP routes learned from one device carry the same origin code. Option B, the higher OMP route preference value, is a real tie-breaker but is applied after administrative distance, and by default every OMP route carries preference 0, so it is not the same-device discriminator described here. Option C, the higher router ID, is a last-resort comparison that only distinguishes routes advertised by different vSmart controllers/devices — a single device has one router ID, so both routes are identical on that field.Community Comment Notes
Shahansa linked the Cisco unicast overlay routing page ending in the fragment about the higher OMP route preference, and Loi2525 endorsed that link as verification of the answer. sdwanlove recalculated and quoted the IOS XE routing book: "select the OMP route with the lower administrative distance," concluding "So it should be D." PepaZdepa33's ordered list likewise places "Prefer routes with lower administrative distance (AD) (on vEdge only)" ahead of "Prefer routes with a higher route preference value." eVo3000 and cc37f90 argued for B with a path-selection list that omits the administrative-distance step, while Roger95 pushed back on D claiming AD is only for multiple routing protocols, and d656971 eliminated C and D by reasoning that AD "is only OMP" — both underestimating that AD is the documented same-device tie-breaker.Official Reference
Exam Strategy
When an OMP question pins both routes to the same device, immediately discard tie-breakers that depend on device identity (router ID, TLOC location) and apply the ordering: active/valid, then lower administrative distance, then higher route preference, TLOC preference, origin, and finally router ID. Remember administrative distance only breaks ties on vEdge, never on IOS XE Catalyst 8000 edges.
Frequently Asked Questions
Why doesn't the higher OMP route preference value win when routes come from the same device?
Administrative distance is evaluated before route preference in the OMP path-selection sequence on vEdge, so it settles the tie first; route preference only applies once AD values are equal.
Why is router ID useless as a tie-breaker for routes from one SD-WAN device?
Router ID comparison only separates routes advertised by different devices. Both routes here are learned from the same vEdge at S4406T9E02F15, so they share one router ID.
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