The MPLS-OPS Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] RE: VRF table lookup for Sites with mutiple VPN membership...
Hi all I have here a document I am in the process of writing but the important content is there there are no diagrams but I believe it explains the operation of MPLS VPNS quite well it is aimed at potential MPLS VPN customers and so is not too technical It has a heavy Cisco Bias as that the perspective from which it is written ( Juniper guys any additions which you think could be made to make it less vendor biased are welcomed ) Comments Welcome but Please set your flamethrowers to low heat :o) I hope I am allowed to post attachments to the group ? Mark: the last page explains the mechanism for populating the VRF's with routing information kind Regards Hill -----Original Message----- From: mpls-ops-request@mplsrc.com [mailto:mpls-ops-request@mplsrc.com]On Behalf Of mpls-ops@mplsrc.com Sent: 27 April 2001 01:42 To: Mark Lewis; mpls-ops@mplsrc.com Subject: RE: VRF table lookup for Sites with mutiple VPN membership... Mark- Thanx for the reply. See my comments inline: > On a PE router, there is one VRF per connectivity requirement. > To illustrate this, suppose the PE router in question is connected to the > following: > > 1. A site in VPN A (which only requires intra-VPN connectivity) > 2. Two sites in VPN B (both requiring only intra-VPN connectivity) > 3. A site which requires connectivity to both VPN A and VPN B > > In the above example there are a total of four sites, but only three > connectivity requrements, and therefore you would have THREE VRFs. So in your example above, say 1 refers to Site P, 2 refers to Sites Q & R and 3 refers to Site S, do we still have three VRF's ? Can you tell me what the contents of the VRF's be (in addition to routes from other CE Routers in VPNs A and B which are directly connecting to some PE's to which the PE in question is peering ) > > As to route lookup within a VRF, it is the same as would be true for a > regular routing table - based on longest match. > Import of routes into VRFs is very important here. Routes are > imported into > VRFs based upon Route Targets (RT). > Routes are exported from VRFs with certain RTs (RTs are BGP extended > communities, and take the form <type><AS number><32bitvalue>, or > <type><IP > address><16bitvalue>). > To provide communication to other sites, you simply import routes > with the > appropraite RTs to the site VRF. > This methodology allows the provisioning of very complex topologies > (connectivity models), eg. simple VPNs, overlapping VPNs, hub-and-spoke > VPNs, etc. > > TIA bala ------- The MPLS-OPS Mailing List Subscribe/Unsubscribe: http://www.mplsrc.com/mplsops.shtml Archive: http://www.mplsrc.com/mpls-ops_archive.shtml |
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