Exam 300-410 topic 1 question 306 discussion

"D" is more accurate. https://notes.networklessons.com/mpls-route-target MPLS Route Target When implementing MPLS VPNs, we use a Route Target or RT to allow PE routers to control the distribution of VPN routes to the appropriate VRFs. Now an RT is actually a BGP extended community attribute that is used to control the distribution of VPN routing information between PE routers.

D is corerct

Correct answer is D (Route Target) High level steps involved in sharing customer route from Site A to Site B Site A PE learns the routes from CE via IGP They are redistributed into BGP under the context of customer vrf To share these routes across to Ps and other PEs, they are exported into Global BGP table "route-target export 11:22" Now in Global BGP table on Site B's PE, they are imported into the customer vrf table with command "route-target import 11:22" They are then redistributed into the IGP between the vrf and Site B CE Same process to share Site B routes to A but with B setting different numeric value for the RT Yes, redistribution (technical word) between BGP and the IGPs is part of the process, but MP-BGP "controls and distributes" (non technical words) customer routes using RT

It is D. https://notes.networklessons.com/mpls-route-target

I was going for D until I found this in official cisco doc •Extended MP-BGP community attributes are used to control the distribution of customer routes. https://content.cisco.com/chapter.sjs?uri=/searchable/chapter/www.cisco.com/content/en/us/td/docs/net_mgmt/prime/fulfillment/6-2/theory/operations/guide/theory/mpls.html.xml#:~:text=Extended%20MP%2DBGP%20community%20attributes,the%20distribution%20of%20customer%20routes.&text=Each%20customer%20route%20is%20associated,correct%20egress%20customer%20edge%20router.

I feel like this should be a choose two kind of question, D is t the only part of customer Route distribution, MPIBGP uses the vpn4 address to redistribute the addresses.

https://www.ciscolive.com/c/dam/r/ciscolive/us/docs/2019/pdf/BRKMPL-1100.pdf • Between PE routers: customer routes exchanged via BGP (MP-BGP) https://www.rfc-editor.org/rfc/rfc2547.txt "PE routers use BGP to distribute VPN routes to each other" "the "Route Target" attribute ... identifies only a set of sites which will be able to use the route" https://networklessons.com/mpls/mpls-layer-3-vpn-explained The PE router will then redistribute everything in BGP (Multi Protocol BGP). https://www.ciscolive.com/c/dam/r/ciscolive/us/docs/2019/pdf/BRKMPL-1100.pdf • MP-iBGP: advertises VPNv4 prefixes + labels "Route Targets dictate which VRF will receive what routes" Interactions Between VRF and BGP VPN Signaling: PE1 redistributes VPNv4 route into MP-iBGP