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IPv6: layer 3 switch sending RA for unique local address prefix, router sending RA for global unicast address prefix

Sam Brynes
Level 1
Level 1

We have a layer 3 switch and a router on the same VLAN.

 

Both have an IPv6 unique local address (ULA) assigned to their inside interfaces.

 

The router is getting a 6rd IPv6 prefix from the service provider.

 

I'd like to advertise the 6rd IPv6 prefix from the router in RA packets so the clients have global unicast IPv6 connectivity. Public Internet traffic should go directly from the client to the router.

 

I'd also like to advertise the ULA prefix from the layer 3 switch in RA packets, and for clients to use their ULA address and route all ULA-destined traffic to the layer 3 switch, not to the router.

 

The clients will be using SLAAC to complete the last 64 bits for both their global unicast and ULA addresses.

 

Is this design possible?

3 Replies 3

pieterh
VIP
VIP

I guess not

- Public Internet traffic should go directly from the client to the router.

would indicate you have a direct L2 connection between the router and the clients (same vlan)

- I'd also like to advertise the ULA prefix from the layer 3 switch in RA packets

would indicate you have a L2 connection between the clients and the L3 switch ,

 

both rules combined would mean both the L3 switch and the router are on the same vlan

-> the client will receive RA packets from both the router AND the switch.

 

Harold Ritter
Level 12
Level 12

Hi Sam,

 

Could you please explain why you need ULA? Why would using only GUA not be sufficient?

 

Regards,

Harold Ritter
Sr Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México
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Cuauhtémoc, Juárez
Ciudad de México, 06600
México

Hi Harold,

Our GUA changes depending on the 6rd prefix that is handed to us by our ISP. Having ULA addresses would allow us to consistently hit the same host.

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