Hi,
I hope someone can convince me the reason behind advertising RD in the BGP update message as this will impose extra consideration and caution during RD assignment. I provided a test scenario to illustrate my point of view more clearly. As far as i know RD is a prefix added to IP address in order to split the TCAM space into distinguish domains for each customer to make sure routing updates of one customer won't be leaking into another. So the purpose of RD is in fact lie on the shared TCAM a router used and the way to make it split ( that's why TCAM capacity decrease once we enable vrf). This reason is enough to claim that RD is local significant assuming that RT is responsible for importing/exporting routes between VPNV4 BGP peers. So I cannot see any point in advertising RD between iBGP peers and in fact it will violate its sheer purposes and somehow interfere with the RT purposes from BGP routing information point of view. To make it clarify i did a test scenario and I attached required show commands on the PEs. To prove that RD is local signifanct in practice, as you can see i assigned RD 100:100 to customer A - attached to R1 and RD100:100 to Customer B attached to R4 and by unique RT assignment you can see (from show route vrf XXX) command that everything is working fine from customer point of view. But there is a leak on BGP routing information and also label assignment which i believe was caused by advertising RD in BGP update. I believe that the BGP update should contain only RT and each router install the routes on the corresponding VRF RD's space. What is the purpose of adverting RD?
Sorry for the lengthy question but it really made me confused.
Accepted Solutions
this example show that using same RD in two different PE make RR select only one path
explain
R3-PE is iBGP with R8-PE
when we check R7-CE we dont see 10.0.0.0/8 ?
because RR select best path and it not select path via R8 it select path via R4, and R3 will not import RT from the R4 and hence R7-CE will not recieve any prefix.
this example show that using same RD in two different PE make RR select only one path
explain
R3-PE is iBGP with R8-PE
when we check R7-CE we dont see 10.0.0.0/8 ?
because RR select best path and it not select path via R8 it select path via R4, and R3 will not import RT from the R4 and hence R7-CE will not recieve any prefix.
