WAN design with backup service provider

Unanswered Question
May 15th, 2010

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Hi,

I need a little help with WAN design.

I already have an WAN infrastructure shown at picture (except L2VPN).

AS65001 is branch location, and AS65000 is datacenter.

Routers R3, R4 and R5 are communicating between themselves using L3VPN. Routers R3, R4 and R5 have same AS number configured, but they have no internal connections (peering) between them and that is the reason why I'm showing them in separate boxes. MPLS L3VPN is another AS ( let’s say it is 65002). All BGP links on picture are eBGP links. All AS in topology are private AS and there are no full BGP tables.

If routers R3, R4 and R5 need to go to (or through) AS 65000 they use R1 as primary gateway. If something is wrong with R1-R3 link, routers R3, R4 and R5 use R2-R5 link.

Design goal

Create redundant links between R3, R4 and R5 using different service provider with L2VPN capabilities, but keep L3VPN as primary links and link R1-R3 as primary for path to AS65000.

I need help with following questions:

1. Should I use iBGP or OSPF for routing between R3, R4 and R5 on L2VPN side?

          - iBGP is slow and OSPF will need redistribution. As I have seen, redistribution is not recommended. How slow will iBGP converge?

2. How to keep L3VPN links as primary links? eBGP has better AD then OSPF or iBGP, but I have never tested this.

3. What parameters should be fine tuned to speed up link failover?

Thank you in advance.

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Paolo Bevilacqua Sun, 05/16/2010 - 04:45

Hi, considering the complexity and criticalness of this design, my recommendation is that you look for professional advice from a reputable consultant, or certified Cisco partner.

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