The MPLS-OPS Archive

[Rajiv Asati <rajiva@cisco.com>]

Hi,

Please see inline...

At 01:54 PM 7/27/2002, M. ELK wrote:
> Hi 
>  
> Ref :
> http://www.cisco.com/warp/public/cc/pd/rt/2600/prodlit/1575_pp.htm
>  
> http://www.cisco.com/univercd/cc/td/doc/product/rtrmgmt/vpnsc/mpls/2_2/prov_gd/
>  
>  
> AA- The first ref does not address clearly how to connect a Multi-VRF CE
> to a PE using eBGP . 

Well, configuring BGP in the Multi-VRF CE is nearly the same as
configuring it on the PE. :)

> The 2nd Ref (page 11-9) provide a template .

Yes.

> Any doc which list a complete config for
> Multi-VRF CE using 
> ebgp to connect to a PE router ?? 

I am not sure if I understand you correctly. 
The page11-9 indeed provides the necessary config needed to
configure  the CE router.
Are you asking about the both PE and CE config when eBGP is used as a
PE-CE protocol.

>  
>  
> BB-from ref 2 : say for 5 VRF on the CE , is it mean a ebgp session per
> VRF between the CE and the PE ?? 

Yes. So we will end up configuring "address-family ipv4 vrf
<name>" for each VRF in the BGP.
So the BGP config on the CE will look like as follows:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bgp <AS#1>
! 
 address-family ipv4 vrf v1
 neighbor x1 remote-as <AS#2>
 neighbor x1 activate
 !
 address-family ipv4 vrf v2
 neighbor x2 remote-as <AS#2>
 neighbor x2 activate
 !
 address-family ipv4 vrf v3
 neighbor x3 remote-as <AS#2>
 neighbor x3 activate
 !
~~~~~~~~~~~~~~~~~~~~~~~
And the PE's config will look like this:

bgp <AS#2>
! 
 address-family ipv4 vrf v1
 neighbor x1 remote-as <AS#1>
 neighbor x1 activate
 !
 address-family ipv4 vrf v2
 neighbor x2 remote-as <AS#1>
 neighbor x2 activate
 !
 address-family ipv4 vrf v3
 neighbor x3 remote-as <AS#1>
 neighbor x3 activate
 !

>  
> Could be easier if the CE  and PE run a modified eBGP VPNV4
> .

Slight correction: PE-CE are not required to run eBGP VPNv4.. rather they
run the normal eBGP (ipv4) session. :)
As we know, eBGP VPNv4 could be interpreted as MP-eBGP which might be run
in the Inter-AS case. 

>  a modified in the sense : 
> At the PE : 
> Say the 5 VRF are VRf1 ...VRF5 
>  
>  interface s1 
>  ip Vrf Forwarding Vrf1,Vrf2,Vrf3,Vrf4,Vrf5 
>  
> address-family VPNV4 VRF vrf1,Vrf2,Vrf3,Vrf4, Vrf5 
> Nei CE remote-as XXX 
> ...
> ... 
>  
> a VPNV4 context is configured per VRF(s) and an interface could be
> linked to several VRF's . 
>  
> For outgoing eBGP update : advertise route from those VRF routing table ,
> no RT ext-community will be exported .
>  
> For incoming eBGP update : import the route to the correspending 
> VRF based on the RD value .   
> (Those recieved eBGP VPNV4 update are within the context of  the
> sepcified VRF (Vrf1 ...VRf5) which mean that they are not propagated to
>    other PE's ) . 

Well, what if the CE is connected to more than one PE in that VRF.
:)

>  
> at the CE :  
>  
> Addrres-family VPNV4 vrf vrf1,vrf2,vrf3,vrf4,vrf5 
> nei PE remote-as YYY 
> .... 
>  
>  . 
>  
> In such case their is  no need to have a sub-interface for each VRF
> between the CE and the PE , Separation of VRF traffic is now based on the
> label .

Well, I don't think that the above approach is viable in the current
implementation, so I will leave it for others to comment. But if the
number of subinterfaces is the concern, then GRE tunnel per VRF could be
an alternative.

>  
> (May be the above is something like Inter-AS RFC 2547 option
> "a" but
>  now is VRF's-to-VRF's  instead of VRF-to-VRF still it is not
> full fledge 
> as option "c" or option "b" )  
>  
> CC- For a Multi-VRF over a CE where it is connected to PE using
>   eBGP (one eBGP session per VRF) ,it is not clear the benefit 
>   (in term of mem and CPU ) of such setup versus the CE runing full
> PE-functionality . Pls clarify .

Well, multi-VRF is for the CE that is not required to run MPLS.. and only
needs basic VRF configuration. Nothing fancy. So VRF concept gets used to
provide the isolation of routing information at the CE itself, without
involving MPLS. 
We could certainly extend the PE functionality at the CE, but then you
end up with CsC architecture and then we don't need multiple interfaces
on the PE-CE. It really comes down to the requirement and type of box.

Please let me know if I could be of further help.

Cheers,
Rajiv

 
Brgds

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