implementing SAN over MPLS

Unanswered Question
Feb 22nd, 2009


we have 2 datacenter (backup), we need to implement SAN over MPLS (perhaps with copper : G.SHDSL, or FO ), is it possible ?

and how can we interconnect the 2 MDS, (through our WAN connexion, router, firewall, IPS...?) or connect directely the MDS to IP MPLS (without other equipment, in this case is it secured ?), with witch interterfaces we interconnect 2 MDS via MPLS?

I have this problem too.
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colin.mcnamara Sun, 02/22/2009 - 12:28

I am assuming that you want to connect two SAN's over a MPLS based service provider (so effectively SAN extension over IP).

The way to accomplish SAN extension over IP is to use an 18/4 card or IPS module to connect your two fabrics together using a FCIP tunnel (fibre channel over ip).

The configuration guide for FCIP is right here -

If you found this helpful please rate it.


Michael Brown Sun, 02/22/2009 - 22:20

MPLS networks can pose a challenge for FCIP

If you do implement FCIP over MPLS, be sure to monitor for out of order TCP packets on the FCIP interfaces. Within an MPLS network, individual FCIP packets may take different paths though the network based on the current network load. This could lead to TCP packets arriving at the destination FCIP interface out or order in some instances. OOO (out of order) packets can lead to decreased performance. I have seen a few MDS install decide to use static routing within the MPLS network to avoid a high % of OOO.

The CLI command to monitor for OOO is

show ips stats tcp interface gigabit x/y detail

Under TCP receive stats, look for Out of Order packets. Be sure to monitor both ends. You might see OOO is 1 direction, and not the other.

Hope this helps,



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