Solved: Problem understanding Multi-vrf CE

mailaglady2 · ‎09-08-2009

Hi

I have a problem configuring multi vrf ce, so I searched on the web for a document that can show me how to do that. I got this document from the net â€œDesigning MPLS Extensions for Customer Edge Routersâ€. url:http://www.cisco.com/warp/public/cc/pd/rt/2600/prodlit/1575_pp.pdf

I don't understand the ip address used there, on page 13 under router BGP 1 the ip add on neighbour 10.13.1.48 isn't that a network address(because if they use a mask 30 then it should be a network address)? Another question on that address still for which router is this address?

On page 17 and 18 for router 2621-ce configurations, is there a specific reason they used loopback mask of 30 instead of 32. On router BGP 3 they used update source of Ethernet is there s specific reason why the used the ethrnet? Why all these loopback since I don't see any loopback attached to any vrf?

The configs between the VXR and RSP-PE-EAST-4 are not included in this document, I wish I could see them. I see a VXR is showing vrf 15 and the tables on figure 8 shows v15, does this mean the VXR and 2611-CE-5 is on the same vrf?

Does any body have or know any document that I can read regarding the multi-vrf ce?

Your assistance would be greatly appreciated.

Giuseppe Larosa · ‎09-09-2009

Hello Mpho,

let's start from figure 8 the multi VRF device has multiple VRFs associated on the right side to conventional CE routers and on the left side to the PE node.

For each VRFliteX there is a link on the right of the multiVRF CE and a link on the left towards PE node.

So the multiVRF CE has multiple address-families ipv4 vrf VRFname.

Actually it has multiple OSPF processes one for each VRF.

In each address-family IPv4 vrf vrfname the multiVRF CE is redistributing into BGP the routes learned on the dedicated OSPF process.

So your understanding is correct.

If we look at a specific VRF vrflite3 for example the configurations of the other VRFs have no impact on it.

they are segregated. The document shows also the capability to support overlapping IP addresses in different not communicating VRFs.

Hope to help

Giuseppe

View solution in original post

Giuseppe Larosa · ‎09-09-2009

Hello Mpho,

a Multi-VRF CE is a device that has multiple VRFs and is shared between different customers and is generally owned and managed by the service provider.

From a technical point of view the multi-VRF CE has a subset of the features of an MPLS PE.

It has the capability to segregate traffic of different customers and to support address overlapping but:

there is no support of MPLS forwarding so there are only VRF access links both to the customer both to the real MPLS PE.

There is no support/need of the MP-BGP for address-family Vpnv4.

The uplink is usually made with an high speed 802.1Q trunk where each vlan carried is mapped to a different VRF/Customer.

The customer benefits are the sharing of the CE device and of the high speed uplink(s).

Scalability is the issue in comparison with a real PE:

a PE with N VRFs can use N+1 interfaces (N access links + 1 MPLS backbone link)

a multi VRF CE with N VRFs needs 2*N interfaces (for each VRF one link towards the customer and one towards the SP PE)

The same is true for the routing relationships: on each VRF a different routing relationship exist with PE (it can be eBGP in VRF or IGP OSPF or EIGRP in VRF) while a real PE has one/two BGP relationships with the RRS and this is enough for all defined VRFs.

Often a Multi-VRF CE is a multilayer switch that can offer high port density at a cheap price.

>> I wish I could see them. I see a VXR is showing vrf 15 and the tables on figure 8 shows v15, does this mean the VXR and 2611-CE-5 is on the same vrf?

each device the multi VRF CE and the PE node sees the other in a locally defined VRF.

That is the multiVRF CE sees the PE as a CE device from its own point of view.

This is a move from standard PE-CE scenario where the CE node is not aware of VRFs.

Edit:

your other questions here:

>> don't understand the ip address used there, on page 13 under router BGP 1 the ip add on neighbour 10.13.1.48

that is the IP address of a loopback on another PE node in service provider cloud, see that under address-family vpnv4 the same address appears.

>> address-family vpnv4

neighbor 10.13.1.48 activate

neighbor 10.13.1.48 send-community extended

neighbor 10.13.1.61 activate

neighbor 10.13.1.61 send-community extended

so these two are IP addresses or remote PE nodes.

here PE-multiVRF CE protocol in use is OSPF with one instance for each VRF.

>> On page 17 and 18 for router 2621-ce configurations, is there a specific reason they used loopback mask of 30 instead of 32. On router BGP 3 they used update source of Ethernet is there s specific reason why the used the ethrnet? Why all these loopback since I don't see any loopback attached to any vrf?

no specific reasons devices downstream the multi VRF CE are standard CE nodes.

Hope to help

Giuseppe

mailaglady2 · ‎09-09-2009

Hi qiuslar

I need clarity, firstly I would like to thank you for your quick response. I had a busy day at work today that's the reason I only respond now. OK going back to the topic. On page 16 & 17 again under BGP 13, there are address-family ipv4 vrflite 5,4,2 and 1 does the address-families have any impact? if yes what do they do. I believe I understand the add-family vrf vrflite3, it redistribute the ospf 13 (vrf) routes into bgp process 13 and advertise the 192.1.3.0 network to the PE router right?

Thanks and regards

Mpho

Giuseppe Larosa · ‎09-09-2009

Hello Mpho,

let's start from figure 8 the multi VRF device has multiple VRFs associated on the right side to conventional CE routers and on the left side to the PE node.

For each VRFliteX there is a link on the right of the multiVRF CE and a link on the left towards PE node.

So the multiVRF CE has multiple address-families ipv4 vrf VRFname.

Actually it has multiple OSPF processes one for each VRF.

In each address-family IPv4 vrf vrfname the multiVRF CE is redistributing into BGP the routes learned on the dedicated OSPF process.

So your understanding is correct.

If we look at a specific VRF vrflite3 for example the configurations of the other VRFs have no impact on it.

they are segregated. The document shows also the capability to support overlapping IP addresses in different not communicating VRFs.

Hope to help

Giuseppe

mailaglady2 · ‎09-09-2009

Hi qiuslar

Do you by any chance know where can I get another multi vrf ce document that I can read to get a clear understanding and perhaps a diffrent approach/setup/configuration of this multi vrf ce?

Thanks and regards

Mpho