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New Member

VPLS to centralized BRAS (HSI service)

What do you think about VPLS as way of transport to centralized BRAS location. I know that cisco propose EoMPLS for HSI in aggragation network, but we have one centralized BRAS, and this BRAS is connected directly to PE router(7609). Is it only solution for HSI in those configuration VPLS? Schema of this network is in attachment.

8 REPLIES
New Member

Re: VPLS to centralized BRAS (HSI service)

Why do you want to use VPLS? Isn't simple EoMPLS enough here? You need VPLS only if you want to provide some multipoint L2 services, which is not the case if I've understood you correctly.

Second, I'd recommend you to buy a new dedicated "Hub"-router for EoMPLS tails. Move it and your BRAS somewhere near core and connect this router with 2 links to the core. It'd help to eliminate traffic asymmetry and reduce configuration complexity.

Third. Are you sure you have less than 4094 VLANs in your whole network?

Logical scheme'd be like this:

L2 net<->VLAN Based EoMPLS from the PE to Hub<->L2 net after Hub<->BRAS.

P.S. That kind of BRAS do you use?

New Member

Re: VPLS to centralized BRAS (HSI service)

How to configure HUB router, as VPLS or EoMPLS? If I use EoMPLS, I cannot configure on PE router where is connected BRAS several xconnect destination for other PEs, only one destination is allow, and I think that is EoMPLS, but if I want to connect one HUB location with more SPOKE locations, I have to use VPLS as mechanism for point-to-multipoint connections. If you think that is EoMPLS possible, which module (card)as core facing module I must have on PE router where is connected BRAS.

New Member

Re: VPLS to centralized BRAS (HSI service)

As EoMPLS.

Sorry I'm writing this in big hurry so mistakes might happen.

Plz see some config example:

1. For any PE Router which connects DSLAM:

interface GigabitEthernet1/1

description To DSLAM

no ip address

! vlan subifs

interface GigabitEthernet1/1.100

encapsulation dot1q 100

xconnect 100 encapsulation mpls

!

interface GigabitEthernet1/1.200

encapsulation dot1q 200

xconnect 200 encapsulation mpls

!

interface GigabitEthernet1/1.300

encapsulation dot1q 300

xconnect 300 encapsulation mpls

!

2. For HUB router:

! GigEthernet1/1 connected to BRAS

interface GigabitEthernet1/1

description To BRAS

no ip address

!

interface GigabitEthernet1/1.100

encapsulation dot1q 100

xconnect 100 encapsulation mpls

!

interface GigabitEthernet1/1.200

encapsulation dot1q 200

xconnect 200 encapsulation mpls

!

interface GigabitEthernet1/1.300

encapsulation dot1q 300

xconnect 300 encapsulation mpls

!

New Member

Re: VPLS to centralized BRAS (HSI service)

Thank you for configuration example, but I want to talk about situation where we want from HUB router from subinterface to BRAS, (example 1.100) transport VLAN 100 to many SPOKE. In your configuration this is not possible, in fact it is possible if we have N physical interface to BRAS from HUB router, where is N number of SPOKE router.

You cannot under subinterface configure this:

interface GigabitEthernet1/1.200

encapsulation dot1q 200

xconnect 200 encapsulation mpls

xconnect 200 encapsulation mpls

New Member

Re: VPLS to centralized BRAS (HSI service)

Yes, you can't, but I don't think you need this.

Let me explain. Generally it's a good idea to have non-overlapping VLAN address space. For instance use VLAN range from 10 to 19 for first PE, 20-29 for second PE, etc. If you are not going to build your network for business clients (they might need VPLS), you should do as simple as you could. In other words your task is quite simple: to extend your L2 network over L3/MPLS infrastructure. So do as simple as you can, use EoMPLS for any vlan in the access network and terminate them at the BRAS.

The only question that might arise is how many vlans do you have (remember about 4094 VLANs).

New Member

Re: VPLS to centralized BRAS (HSI service)

Do you want to have the same VLAN ID (vlan 100) at DSLAM side to make operations simpler or to use only one vlan i.e vlan 100 for transport of traffic between DSLAMs and BRAS ?

New Member

Re: VPLS to centralized BRAS (HSI service)

In my opinion from the operational point of view is better to have the same vlan ID at the access side and different at the BRAS (to make difference) - kind of vlan translation. It requires 'vlan local significance' feature on the switches where dslams are connected. If you are still considering VPLS for HSI service remember about: MAC address scalability issue and direct connections between dslams (vpls is kind of L2 broadcast domain connecting all particular DSLAM's VLAN(s) together).

Regards

Adam

New Member

Re: VPLS to centralized BRAS (HSI service)

Guys:

Rather than having locally significant vlans on the spoke side you should have SIP/SPA cards on the PE which can take the same vlans. For example you can load a 7613 with 5 SIP cards (6*4094 VLANs).

Moreover most of the BRAS also will have local vlan significance.

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