[c-nsp] NX-OS - Fabric Path

[Lincoln Dale]

On 19/07/2010, at 11:08 PM, Manu Chao wrote:

> DRILL...
> *Will Fabric Path* be based on OTV?

no.

OTV is a technology that allows us to extend L2 across any L3 (IP) infrastructure.  Cisco Fabric Path is in essence the ability to run L2 networks without spanning tree and all links active.


Cisco Fabric Path is a term we are using for what is in essence what will be IETF TRILL / RBridges (http://datatracker.ietf.org/wg/trill/charter/) with enhancements.

right now the hardware is using a frame format that is not that of what TRILL uses (and as such we're using a Cisco-defined ethertype), however the hardware is capable of supporting standards-based TRILL as and when the standard is finalised & ratified.

there are numerous other things involved in achieving that too - changes to how mac learning happens, mechanisms for not having to learn every mac address at edge ports or on unidirectional communication - how one can run FHRPs (HSRP, VRRP, GLBP) active/active - and more - hence why we've using a Cisco term for the technology.

both OTV and Cisco FabricPath (& TRILL) use ISIS as the link-state routing protocol but their use is vastly different between them.  in FabricPath & TRILL, ISIS is used to build the topology of _switches_ and (multiple) topologies that run over those switches for e.g. unicast, broadcast, multicast.
in OTV, ISIS is used for advertising the mac-addresses of connected devices in the network.



On 20/07/2010, at 7:42 AM, Phil Bedard wrote:
>> From my understanding the initial FP is proprietary and uses 802.1ah (mac-in-mac)
>> encapsulation which is very different from TRILL which has its own header format which is not MAC address based (canonical nicknames instead.)  Cisco has said they will support standard TRILL at a later date. 

much of what you've stated here is fairly accurate except for that its based / uses 802.1ah.
nothing to do with 802.1ah.


cheers,

lincoln.