questions about RD, RT and VRF-lite

sufianallan

Hi to All,

Any body who is exposed to VRF-Lite, RD and RT i need your help in understanding the concepts about them. Here are my concerns:

- RD : is used to hide the ip address of one customer, if another customer is using the same ip address..right? can the value of RD for customer A be the same RD value for customer B..example { IP vrf customer-A , RD 1:1} and { IP vrf customer-B, RD 1:1}
or it has to be different so the router would know which is which?


- RT : this is used with import and export..right?...and the value for the import is the same value that the customer is exporting and the export value that we are exporting should be the value of import that the customer is importing...example:

IP vrf customer-A
RT import 1:9999...the customer should use the value that am exporting for some routes
RT export 1 :1000


our network

IP vrf customer-A
RT import 1:1000.....i will use the value that the customer is exporting for some routes.
RT export 1:9999


im not sure if i get it or im just confused, can someone explains it to me like a baby with some examples.?



thank you guys so much:D

sufianallan

Where are the experts?

networker050184

RD - This is placed on the prefix and used to make it unique. It would not be wise to use the same RD for multiple customers especially if they are using overlapping IP space. If both customers used 10.0.0.0/24 with an RD of 1:1 the NLRI for that prefix would both be 1:1:10.0.0.0/24.

RT - Used for import/export. You can use this however you want. It is basically a tag you can put on routes for controlling what routes are populated into a VRF. You can also use route-maps to only mark certain routes with certain RTs for a more granular filtering control.

EdTheLad

RDs allow customers to share address space in the core, or as you said hide their ip addresses. Its basically adding another tag to the address that can be modified to make the same ip addresses appear different.Now as you have asked do the customers use the same RD, well that would negate the whole idea behind using a RD. So in a classic configuration a unique RD is assigned to every customer.

RTs are as you have explained.

sufianallan

guys, i surely appreciate your input