The MPLS-OPS Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] RE: MPLS VPN Help!
Hello Here some basic explanations about RD and RT and how they are used --> RD Route Distinguisher aim: make routes unique, distinguish between VRF (virtual routing tables) on same PE set: on the vrf and attached to all routes when redistributed into MP-BGP rule 1: no 2 VRFs on the same PE may have the same RD rule 2: the combination of <RD>:<ipv4 address> (=VPNV4-address) needs to be unique in the provider network as BGP (or better MP-BGP) only forwards the best route --> RT Route Target aim: mechanism for implementing VPN policy; i.e. allowing the controlled interchange of routes between various VRF-tables on various PE`s set: as export on the VRF ( all or specific routes get one or more RTs attached as Extended Community Values) control: set as import RT (all or specific routes having at least one matching RT will be imported into local VRF) --> now why is RD different from RT ? the reason is that by separating both mechanisms you have more flexibility in combining complex VPN topologies ( hub&spoke, overlapping VPNs,.....) but both RD and RT can have the same value as they have nothing in common than the same recommended format of <AS-nr>:<number> some basic examples: -> simple VPN (any to any connectivity within an VPN) RD=RTexport=RTimport=100:1 all sites have the same RD, more than one site connected to the same PE can share the same VRF, all routes get exchanged between all sites -> central services VPN (any site of aVPN can connect to a central site but no site-to site connectivity allowed) one RD per site if more than one site connects to the same PE, sites on different PEs can have the same RD (only addresses within VPN have to be unique) all sites have RTexport= 100:2, RTimport=100:3 central site has RTexport= 100:3, RT import=100:2 so all central routes get exported to all sites, and teh routes of all other sites get exported to the central site, but there is no routing exchange between the sites, so only connectivity to the central site is given. -> and all other possibilities.... Hope that helps with best regards Alexander Marhold Senior Consultant PRO IN -----Original Message----- From: Dany Ang [mailto:ang.com@rocketmail.com] Sent: Saturday, March 31, 2001 8:53 AM To: mpls-ops@mplsrc.com Subject: MPLS VPN Help! HI: First of all I introduce myself. My name is Ang. Actually I'm building a java simulator for the MPLS VPN. I am confusing with the Route Target and Route Distinguisher. How we define the route target? is it service provider who manualy setup or how? Why we need another Route Target, although we have already use RD? . Any article about the attribute of VRF. Best Regards Ang ===== __________________________________________________ Do You Yahoo!? Get email at your own domain with Yahoo! Mail. http://personal.mail.yahoo.com/?.refer=text ------- The MPLS-OPS Mailing List Subscribe/Unsubscribe: http://www.mplsrc.com/mplsops.shtml Archive: http://www.mplsrc.com/mpls-ops_archive.shtml ------- The MPLS-OPS Mailing List Subscribe/Unsubscribe: http://www.mplsrc.com/mplsops.shtml Archive: http://www.mplsrc.com/mpls-ops_archive.shtml
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