How many ways can we connect two different vrf network

[wfqk]

Hi Please see the attached diagram where there are two vrf networks, blue and red. all blue and red routers are configured without vrf to connect to ISP configured with vrf red and blue. The question is how many ways can we have the blue and red communicate? One is to add another router between the Blue and Red. Do you agree? Thank you

ISP(config)#interface FastEthernet 0/0

ISP(config-if)#ip vrf forwarding Blue

ISP(config-if)#ip address 192.168.1.254 255.255.255.0

ISP(config)#interface FastEthernet 1/0

ISP(config-if)#ip vrf forwarding Red

ISP(config-if)#ip address 192.168.2.254 255.255.255.0

ISP(config)#interface FastEthernet 2/0

ISP(config-if)#ip vrf forwarding Blue

ISP(config-if)#ip address 192.168.3.254 255.255.255.0

ISP(config)#interface FastEthernet 3/0

ISP(config-if)#ip vrf forwarding Red

ISP(config-if)#ip address 192.168.4.254 255.255.255.0

[a.alekseev]

1. rename "red" to "blue"
2. make logical loop (a gre tunnel between vrfs "red" and "blue"
3. make physycal loop (connect back to back two interfaces)
4. run bgp and use the same route-targets for vrfs

[wfqk]

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@a.alekseev wrote:
3. make physycal loop (connect back to back two interfaces)

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Can we add a cable or a switch as physical loop between router Red2 and Blue2? Thank you