Which Private TLOC Colors Form Control Over Public IP?
Refer to the exhibit. The sites are connected over different ISP carriers. The client requested that the engineer choose private TLOC colors that would form the control connections over the public IP. Which configuration accomplishes this task?
Community Insight
The question tests whether you can distinguish private TLOC colors from public ones and pair the color with the correct carrier index shown in the exhibit; the trap is selecting a public color like lte or custom1, or a private color bound to the wrong carrier.
Private TLOC colors such as metro-ethernet and mpls are the only colors that build control connections directly over the public IP of each WAN transport. In this exhibit, option B is the configuration that satisfies the client because it uses a private color (metro-ethernet) together with the carrier index that matches each site's ISP link.
Option C is the popular wrong pick because learners assume custom1 is meant for an ISP-facing link, but custom1 is treated as a public color rather than a private one; option D also fails because its mpls color is paired with a carrier index that does not match Site B (vEdge2) in the exhibit.
Community Discussion (4 comments)
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Expert Analysis
Why the Answer Is Correct
Option B configures metro-ethernet, which is one of Cisco SD-WAN's documented private TLOC colors (along with mpls and private1–private6). Because the color is private, the TLOC forms its control connection directly to the remote TLOC's public IP address rather than depending on public-color NAT behavior, which is exactly what the client requested. Option B also binds that private color to carrier 2 for Site B (vEdge2), matching the ISP carrier assignment shown in the exhibit, so the control connection is built over the intended transport link. Both required constraints — private color and correct carrier — are therefore satisfied at the same time.Why the Other Options Are Wrong
Option A and option C rely on lte and custom1, which are public colors, so they cannot be the answer to a request that explicitly says "choose private TLOC colors." Choosing a public color would also change how the control connection is sourced, defeating the stated design intent of building control traffic over the public IP from a private-color TLOC. Option D is the subtle trap: mpls is genuinely a private color, but the carrier index it assigns does not line up with the per-site ISP carriers in the exhibit, so the control connection would not form on the correct link. A private color bound to the wrong carrier is just as unusable as a public color, which is why D is rejected.Community Comment Notes
Daniel_666, whose comment drew the most likes, anchored on the wording "choose private TLOC colors" and observed that lte and custom1 are public colors, concluding B. cc37f90 independently listed the private color set (mpls, metro-ethernet, private1 through private6) and added "Carrier 2 is for Site B (vEdge2)", which is the detail that separates the passing option from a merely private-colored one. westh4m1234 asked "what is the difference in colors for B & D both are private?", and the answer lies in the carrier index rather than in the color itself. A single dissenting vote went to C on the reasoning "custom1 for ISP", which mistakes a public/custom color for a private one.Exam Strategy
When a question says "private TLOC colors," immediately eliminate every option containing biz-internet, public-internet, lte, or custom-style colors before comparing anything else. Among the surviving options, verify the carrier index against the exhibit's per-site ISP link, because that is the usual tiebreaker between two private-colored choices.
Frequently Asked Questions
Why are lte and custom1 not valid private TLOC colors here?
They are public colors in Cisco SD-WAN, so a TLOC using them is treated as a public color and does not meet the client's request for private TLOC colors.
Why is option D wrong if mpls is also a private color?
mpls is private, but option D binds it to the wrong carrier index; the exhibit requires carrier 2 for Site B (vEdge2) so the control connection uses the correct ISP link.
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