Subject: Questions on multiprovider VPN operations in RFC2547bis

From: [email-masked]
Date: Tue, 2 Jan 2001 12:15:36 -0800

Hello,
     RFC2547bis supports multiprovider VPNs in which a VPN customer has two
sites each served by a distinct VPN service provider.  The VPN service providers
serving the customer are themselves served by yet another VPN service provider.
Suppose we have the following VPN deployment,

     CE1  ---  (PE11  --  P1  -- PE12)  ==  (PE21 --  P2  -- PE22)  ==  (PE31
--  P3  -- PE32)  --  CE2

PE11, P1, and PE12 are in AS1, PE21, P2, and PE22 are in AS2, and PE31, P3, and
PE32 are in AS3.
Assuming that  P1 and P3 are route reflectors and are talking EBGP to each
other.  So when PE32 advertises a VPN-ipv4 route for CE2 to P3, P3 will in turn
advertise the route to P1.  When P1 receives the advertisement, it will then
send the advertisement to PE11 and PE12.

Here are my questions:
     (1) A VPN service provider can assign route distinguisher (RD) at its own
discretion.  So the VPN customer's RD in AS1 will likely be different from its
RD in AS3.  When P1 receives the VPN-ipv4 route advertisement from P3, does the
RD in the advertisement need to be converted first before being sent to PE11 and
PE12?
     (2) How about route target extended communities?  Do they need to be
converted too?
     (3) Can anyone show me a detailed diagram with both the control plane
set-up and the data plane forwarding for the above VPN deployment scenario?

Regards,
-- James Huang

---

From: Yakov Rekhter <[email-masked]>
Date: Tue, 02 Jan 2001 12:33:39 -0800

James,

> discretion.  

Correct.

>             So the VPN customer's RD in AS1 will likely be different from its
> RD in AS3.  

Correct too.

> When P1 receives the VPN-ipv4 route advertisement from P3, does the
> RD in the advertisement need to be converted first before being sent to PE11 
> and PE12?

No, it does not *need* to be converted. However, P1 *may* do the
conversion. 

>      (2) How about route target extended communities?  Do they need to be

The same applies to route targets. They need not be converted by P1.
But P1 *may* do the conversion.

Yakov.