FCIP/ISL Question

[ddmikeollington]

Hello All,

Apologies for what must be a basic question but I'm struggling to find a reference for this, is it feasible to establish two FCIP links between the same pair of MDS without a portchannel with all the Ethernet links from both MDS in the same VLAN (stretched Layer 2 VLAN between 2 DCs)?  Does FSPF prevent a "loop" in this configuration?  My customer has tried to implement this in the past but suffered from extremely poor performance every time the second FCIP is enabled.

Reviewing the configuration guides, the recommendation seems to be to:

Configure host static routes out of the relevant Ethernet interfaces for the relevant remote MDS Ethernet interfaces

Establish the FCIPs

Aggregate the FCIPs with a PortChannel

Does that seem like the best approach?

Cheers,

Mike

[dynamoxxx]

Mike,

why not portchannel them together ?

[ddmikeollington]

Well, quite, I need to ask them that.  The remnants in the MDS configs don't suggest they've ever tried. 

If they're not portchannelled, is there a risk of a loop (with the same implications as an Ethernet loop) or does FSPF prevent that?

As I said, apologies, I'm a noob to FC and I haven't found a good reference.  Cisco documentation which doesn't specifically include something tends to suggest it's not supported.

[dynamoxxx]

nothing will happen if they are stand alone links, each ports gets assigned an ip address on the local subnet and you create a tunnel between the two. MDS does a pretty good job load balancing between the two individual links but portchannel is better, gives you a fatter pipe. If one fcip link drops ..fabric does not care, if individual link drops ..fabric may go through some kind of reform ..which may be disruptive to some hosts.

[ddmikeollington]

Thanks for that, useful info.  I'll get some more history from them.  Cheers, Mike