[AusNOG] Outage that costs Millions

[Narelle]

On Wed, Jun 30, 2010 at 3:04 PM, Lincoln Dale <ltd at cisco.com> wrote:
> On 30/06/2010, at 1:00 PM, Andrew Fort wrote:
>> What's your view on TRILL?
>
> Rbridges - Layer 2 Forwarding Based on Link State Routing - what isn't there to like about that? :)


I'll echo that one. I have seen *major* spanning tree problems in data
centres, campuses and across exchanges. In the Olden Days we used to
get them due to faulty bridges, and more recently from bugs/tricky
configs due to link aggregation. They are the hardest things to locate
and often it seems that ultimately all you did was wave the proverbial
dead chicken, ie you pulled a card somewhere and the darn thing
converged...

Actually I remember a classic conversation a while back with Radia
Perlman (she invented it) about how unsuitable I thought it was for
MANs... she agreed wholeheartedly!

Might be time for some poetry to sooth our souls...

Algorhyme

I think that I shall never see
A graph more lovely than a tree.
A tree whose crucial property
Is loop-free connectivity.
A tree that must be sure to span
So packets can reach every LAN.
First, the root must be selected.
By ID, it is elected.
Least-cost paths from root are traced.
In the tree, these paths are placed.
A mesh is made by folks like me,
Then bridges find a spanning tree.
—Radia Perlman





Cheers


-- 


Narelle
narellec at gmail.com