MPLS-over-IP?

[Davezenith]

Does any Cisco gear support MPLS-over-IP (as per http://tools.ietf.org/html/draft-worster-mpls-in-ip-03 )?  Searching Google finds several pages with references to it as being a possibility but no examples of any implementations.  In practice, is it necessary to use IP tunnels to transmit MPLS datagrams between non-adjacent LSR's?

[Ivan Krimmel]

Hi David,

will MPLS/GRE do the job?

[Davezenith]

Hi Ivan

MPLS/GRE will work, but we're hoping to avoid the GRE protocol overhead (and the admin overhead of setting up all the tunnels) if at all possible.

[Peter Paluch]

David,

I have seen that draft for the first time right now. My immediate thought is that using this kind of tunnel instead of GRE tunnels saves you only 4B of overhead (the basic GRE header is 4B long) - a size of a single MPLS label. An extra IP header will still be present, so the total tunnel overhead is 20B, and with GRE, 24B. I am not sure if those extra 4 bytes are that important.

Moreover, the MPLS-in-IP draft does not specify any kind of endpoint discovery. I would assume that these tunnels would have to be established manually just like GRE tunnels.

Please correct me if my reasoning here is wrong.

Best regards,

Peter

[yashfaqu]

Hi,

I believe Peter is right, you will need endpoint discovery to make it work.

Yasir

[Davezenith]

Peter,

Thanks for the feedback. I agree with you.  MPLS/GRE it is.

Rgds

David

[rsimoni]

Hi David,

let me also add that you need specific hardware to make MPLSoGRE work (i.e. if your router is a Cat6500 or Cisco 7600 you need a SIP-400 or ES+ as core facing interface).

This is something else to take into consideration.

Riccardo