I often get three questions about TRILL: Are the TRILL standards finalized? Has anyone implemented it? Is it useful?
Short answers: Yes, No, Maybe (although I remain unconvinced).
Are the TRILL standards finalized?
The TRILL working group has produces several RFCs and is still working on numerous draft documents. The core RFCs it has produced (RFC 6325 – RBridge Base Protocol, RFC 6327 – RBridge Adjacency and RFC 6439 – RBridge Appointed Forwarders) are all Proposed Standards, and together with RFC 6326 (TRILL use of IS-IS) give enough information that someone could start writing a TRILL-compliant implementation.
Some people think that the Proposed Standard status of these documents means the standards are not finalized. If you’re one of them, read the RFC 2026 (Internet Standards Process) first – the proposed standard status indicates a standard’s maturity level.
Every IETF standard starts as a proposed standard until there are at least two independent interoperable implementations, at which point its status could have been changed to draft standard (no longer – RFC 6410 removed the draft standard maturity level). Only when a technology reaches a “high degree of technical maturity” and “provides significant benefit to the Internet community”, the corresponding RFC becomes an Internet standard.
Just to give you an example: RFC 4862 – IPv6 Stateless Autoconfiguration (SLAAC) is still a draft standard, although there just might be more than a few interoperable implementations, and it happens to be occasionally used in a few networks.
Summary: the core TRILL standards are finalized, but of course the TRILL working group is still developing numerous add-ons.
Has anyone implemented TRILL?
Do you mean the likes of HP and Force10 that have been talking about TRILL for years? They’re still living in the TRILL promiseland.
I might have missed a vendor launching a TRILL-like solution, but so far I’m aware of only two vendors with something remotely similar to TRILL: Cisco’s FabricPath (which, like TRILL, uses IS-IS, but has its own encapsulation format) and Brocade’s VCS Fabric (which uses TRILL packet format and a proprietary version of FSPF as the routing protocol).
Summary: Nobody has implemented the core TRILL standards in a way that would have a remote chance of being interoperable with anyone else.
Is TRILL useful?
You haven’t been reading my blog lately, have you? Why don’t you start with Does TRILL make sense at all?
The original RBridges idea Radia Perlman had (assuming I understood it correctly), which would effectively turn an IP subnet into a CLNP-like IS-IS area, would be interesting (more so if the RBridges would have enough IP awareness to act as ARP proxies and reduce the broadcasting). Unfortunately her simple idea deteriorated in the TRILL working group as soon as networking vendors started slapping all sorts of VLAN-related concoctions on top of it (watch her reaction in this GoogleTalk video when someone asks a VLAN-related question).
TRILL would have been useful five years ago. As things stand right now, the primary use case (large VLAN-based virtual networks within a data center) will no longer be relevant well before we’ll see two interoperable TRILL implementations.