The way I understand it is the remote recieving router uses it to decide which RT's to look at. For example say your remote PE has connections to both customer A and B. The route arrives with the RD A 10.0.0.0/8, ok then look in the RD A set of RT's, ok those RT's tell us to import this route. Now something arrives with RD B 10.0.0.0/8, now look in the RD B set of RT's to decide if we should import. If something just arrived 10.0.0.0/8 how would it know which RT to use?
On Fri, Jan 15, 2010 at 6:38 AM, Taqdir Singh <[email protected]> wrote: > Hi Marko, > > Thanks, but please help me in understanding more on this.. > > Suppose we have One PE router (Se0/0 is connected to customer A (VRF A), > Se0/1 is connected to customer B that is VRF B > > When route (10.0.0.0/8) hit on se0/0 from customer A router, PE router > will put those routes in VRF A routing table > > and > > when route (10.0.0.0/8) hit on se0/1 from customer B router, PE router will > put those routes in VRF B routing table. > > and then finally MP-BGP will send those VPN prefixes to Remote PE router > > and remote PE router will only just match RT and then will put into > corresponding VRFs. > > So when we say RD keeps the prefixes unique by adding RD in front of it but > in what manner ? > > we have RT that is also going along with it and on remote PE only RT is > checked and on the remote end also customer A route 10.0.0.0/8 will be put > into VRF A by matching its RT and customer B route 10.0.0.0/8 will be put > into VRF B by mathcing its RT > > So all the way along where is RD actually helping in keeping the routes > unique ? > > > > On Fri, Jan 15, 2010 at 3:45 PM, Marko Milivojevic <[email protected]> > wrote: >> >> > I know RD keeps 10.0.0./8 of customer A separate from 10.0.0./8 of >> > customer >> > B. >> >> And this is good understanding. Now, for the final bit - that's the >> ONLY thing it does! >> >> > But if the final import export is done on the basis of RT, where RD is >> > actually being compared ? >> >> Nowhere. The only purpose of RD is to keep prefixes "unique", i.e. >> allow overlapping IPv4 address space by prepending them with RD. >> >> -- >> Marko Milivojevic - CCIE #18427 >> Senior Technical Instructor - IPexpert >> >> Mailto: [email protected] >> Telephone: +1.810.326.1444 >> Fax: +1.810.454.0130 >> Community: http://www.ipexpert.com/communities > > > > -- > TAQDIR SINGH > Network Engineering > (+91) 991.170.9496 | (+91) 801.041.5988 > > One who asks is a fool for a moment, one who doesn't ask remains fool for > ever > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
