In an MPLS VPN network, how are customer routes controlled and distributed?
In an MPLS VPN network, how are customer routes controlled and distributed?
In an MPLS VPN network, customer routes are controlled and distributed through the use of route targets. Route targets are BGP extended community attributes that dictate which Virtual Routing and Forwarding (VRF) instances will receive specific routes. By applying route targets, PE (Provider Edge) routers can manage the import and export of routes to the appropriate VRFs, effectively controlling the distribution of customer routing information.
"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.
Similar to Question #117 . https://www.ccexpert.us/mpls-design/chapter-5-packetbased-mpls-vpns.html The distribution of VPN routing information is controlled through the use of VPN route target communities...
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 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.
I had a typo, “D is not the only part of control and distribution”
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
The Q is how are customer routes controlled and distributed? D is correct. This is a classic cisco Q... I feel you tho
Hi Robi, I can accept route targets (D) as the answer because of the word "controlled". Still, MP-BGP could be an answer to how are routes distributed.
D is corerct
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.
Route Target is an extended community attribute in MP-BGP
C does not actually say "MP-BGP" it just says "BGP", so of course if it said "MP-BGP" it was considered a better answer, however, it just said "BGP".