Cisco ASR 920 as a PE Router

[de1denta]

Hi All,

I needs some advice on the suitability of a Cisco ASR 920 that will act as a PE router

We are looking to terminate customer ethernet circuits into our PoP to provide Internet, MPLS, VPLS services. Our provider will aggregate the customer tails onto a single 1Gbps port with each customer being presented as a separate VLAN. Customer A VLAN 101, Customer B VLAN 102 etc.

Each customer will then have a CE installed that will present a different port for Internet, MPLS etc with a different inner VLAN tag being pushed to differentiate the service. So internet services arriving in our PoP for Customer A will have an inner tag of 11 and outer tag of 101

My plan is to terminate the ethernet circuit from our provider onto a port on the ASR 920 and then using EFPs and dot1q matching to place the traffic into the correct service. Internet traffic will be placed into a bridge domain in the global VRF and MPLS traffic will be placed into a bridge domain in the customer’s VRF.

Does this sound like a feasible solution? Carrier Ethernet is new to me so please let me know if I'm completley on the wrong track here

Thank you

[Adam Vitkovsky]

Hi,

The ASR920 was exactly designed for what you described.

The config might look something like this:

interface GigabitEthernet0/0/0

   service instance 1 ethernet

    encapsulation dot1q 101 second-dot1q 11

    vrf forwarding internet-vrf

    ip address 10.1.1.1 255.255.255.252

   service instance 2 ethernet

    encapsulation dot1q 101 second-dot1q 12

    rewrite ingress tag pop 1 symmetric

    bridge-domain 100

   service instance 3 ethernet

    encapsulation dot1q 101 second-dot1q 12

    rewrite ingress tag pop 1 symmetric

l2 vfi PE2-VPLS-A manual

 vpn id 100

 neighbor 10.1.1.1 encapsulation mpls

 neighbor 10.3.3.3 encapsulation mpls

 bridge domain 100

l2vpn xconnect context con1

 member GigabitEthernet0/0/0 service-instance 3

 member Pseudowire 100

template type pseudowire eompls

 encapsulation mpls

!

interface Pseudowire 100

 source template type pseudowire test

 neighbor 10.13.13.13 1

adam

[de1denta]

Hi Adam,

Thanks for this. Quick question (hopefully) - the L3 interface for the Internet VRF needs to be configured on a Cisco ASR1001-X and not on the ASR 920. The ASR1001-X will be directly connected to the ASR 920.

To acheive this, will I need to modify the EFP 'service instance 1 ethernet' in your above example and place it in a bridge domain and then do the same on the ASR1001-X with a BDI interface?

[Adam Vitkovsky · Accepted solution]

Hi,

That depends on how is the link between ASR 920 and  ASR1001-X is configured,

If it’s just a L2 trunk then:

On ASR920 you can use the same EFP config style on both:

the interface facing your provider

the interface facing  ASR1001-X

and then you can join the particular EFPs (service instances) on these interfaces via common bridge domain.

But bridge domain works like a switch so it will start learning mac addresses, so I’m thinking that in this case you should be able to disable mac-address learning for these p2p bridge-domains.

On ASR1001-X side of the link to ASR920 you’d use the same EFP config style but here you’d use the IP address and VRF on the particular EFP(service instance).

If it’s L3/MPLS then:

You can use PW/xconnect configuration on ASR920 (my example service instance 3  -linked to l2vpn xconnect context con1)

But on ASR1001-X side you would need to use “PW Head End” (PWHE) feature to terminate the PW on an L3 interface and the PWHE is not supported on IOS-XE, I think.

adam

[de1denta]

Thanks Adam