Sacrificing Chickens!

Well, I have to say that the gods of technology are thwarting me...
[such gods being as plausible as any others]

My desktop machine is a Ubuntu machine for now. Mostly OK but causing issues from time to time. When they insisted on "unity" for my desktop I rebelled and went for good old gnome.

But the latest is a quirk with NFS. Unable to log in as I could not mount my home directory - I gave up and called in the big guns: Cliff, with comments from Paul, managed to get me back on-line. When Jimi is back from being in a field somewhere he can fix, and by fix I mean install Fedora.

While they worked I used the console - 80 column text on a 30" monitor to use irc. I did not need my reading glasses!

Of course, the answer is, in any god like ceremony, especially pagan...
Sacrificing chickens!

Is this IPv6 NAT? Someone shoot me!

Setting up a new Apple Airport Express as last one died. What do I see?

WTF is "IPv6 Connection Sharing" and why would you ever ever ever need it?

Update: Several comments suggest this is merely prefix delegation - I do hope so.

Finally, a UK mains plug you can put in your pocket.

One does not simply put a UK 3 pin mains plug in your jeans pocket. It will tear clothes and/or hurt you. Yet some times you want to take a USB charger with you...

I have been watching these people for a while, and I get the impression they have issues with the British Standard or some such - seems to taken forever. They have some clever ideas for foldable mains plugs and even compact multi socket mains adapters - but now they are on sale (well, the USB chargers are) at firebox. Well done.

Barclays Fraud Dept

Well I am bracing myself for my holiday - I have more than one debit card and expect to take some cash too.

It is such a trauma going on holiday - even if you tell your bank - even if you spend thousands on plane tickets to the destination using the very same card - they may - just for the hell of it - block your one and only card when you are there in a queue in a supermarket in a foreign country in the name of "fraud protection".

When we went to Barbados a few years ago that happened. My Barclays card would not work. By some fluke I had with me a Lloyds card for an  account I had opened some years before, still valid, just, and never ever used, but had a £1000 overdraft on the account even if £0 balance from opening. The card was not even signed (oops). That worked, the Barclays one did not. I spent hours on calls (expensive ones) from Barbados getting Barclays to fix it. I was not repaid for that time or money.

So I am dreading my next holiday. Will they will try and protect me from fraud yet again?

But hang on - who are they protecting - who would be defrauded here?

I had this discussion with my bank manager (who comes to see me some times). I said I did not want this hassle - and he was shocked. Did I really want to "disable fraud protection" on my card. Sadly, even though I said yes, he was unable to do this.

You see the "fraud protection" is not actually to protect me!

It is a shame they will not actually be honesty about this even...

I am in very little danger of suffering from fraud - to do that someone would have to "fool" me. Someone would have to lie to me for some gain. What is far far more likely (and did happen once, and was not picked up by these idiots) is someone pretends to be me when asking the bank for money (typically, via some merchant).

Now, if that happens, who has been lied to? The merchant and the bank, that's who! So that is who has suffered some sort of fraud, not me. I would suffer (temporarily) the hassle of the bank mistakenly reducing the balance on my account thinking I had asked for money.

Only if I was somehow careless and gave out some details which I should not have (and contractually agreed not to, etc) like my PIN, would I, perhaps, be in some way liable for a fraud against the bank - i.e. only if they could say "well, we thought it was you because they had your PIN", etc, could they pass on that liability. I am not that daft, and some of my cards do not have a PIN even!

So, at the end of the day, I would far rather they did turn off their "fraud protection". The worst that could happen is they mistakenly take money from my account (which they have to put back when they realise it was not me) and so stop some transaction happening later as no money left. From my point of view this is exactly as annoying as them blocking my account because they think something legitimate is in fact fraud. It does not help me at all, in any way, whatsoever.

Well, we'll see. Listen to Mitchell & Webb's view on this.

Apparently *we* are BT Retail, that explains it!

That same fault where they suggest we get a BT Home Hub 3, we contact them about the fault not actually being fixed and the stupid notes...

The notes they then put on the fault about Dan calling them :-

"Dan from CP BT Retail contacted regarding want to rasie [sic] an escalation."

So, we are BT Retail are we, that explains why we should have BT Home Hubs.

Arrrrrrrrrrrrg!

Some details for the interested...

We generally like FTTC, not only because it is fast, but because the service is an Ethernet level handover. One of the classic issues with any fault is that "line" related issues (errors, low sync, drop outs) could be the modem or the wiring or the line or the DSLAM, and only some of that is BT's responsibility on ADSL services.

With FTTC the line, and the modem, are BT's responsibility, and they are even a BT install so the wiring from BT telephone NTE to BT VDSL modem is BT's as well.

This particular customer has a line forecast to get around 60Mb/s sync. He has a 40Mb/s capped service (standard FTTC) and does sometimes get the full rate (which works out just over 39Mb/s IP rate). However, he loses sync a lot and syncs at lower speeds at lot.

When the engineer went out the sync was 16Mb/s, having been 8Mb/s over night - clearly a fault for a line that should get 40Mb/s and be capable of 60Mb/s.

Yet the engineer reports "Customers Equipment, Error or Misoperation;End User own equipment" and tries to blame the PPPoE router not being a BT Home Hub 3. The line syncs even when no PPPoE router present at all, and the PPPoE router cannot affect that in any way.

Naturally our escalations team is on the case our end!

Get a home hub 3 from BT?

Advice from BT regarding one of our FTTC customers:-

"Change the router that they had installed as it was not a BT home Hub3."

"Router that was installed was not a BT home hub3, so i suggested that the they get one from BT."

Hmm, nice one BT, not! Trying to sell your products to our customers when we are paying you to fix a broken service that we pay you for.

[ref 1-12439644949]

Just to explain - Fibre To The Cabinet (FTTC) is a service which BT sell to end users as BT Infinity, and include in their service a BT Home Hub router product. It seems a nice enough broadband service.

We, as an ISP, provide our customers with an FTTC service. This uses the same underlying technology at the exchange and cabinet and in the premises as far as the handover point (PPPoE port on a VDSL modem). Unlike BT, the service we sell does not include a BT Home Hub (obviously) and is not called BT Infinity. We provide a different router (which does IPv6, by the way). The service has many differences apart from that, including a fixed IPv4 address or addresses, IPv6, a UK domain, and our constant line performance monitoring. Oh, and we provide access to the Internet without filtering.

Sadly, when something breaks, we often have to get a BT engineer out to fix it, as they have an exclusive right to work on the national infrastructure that is the BT network. They do say some annoying things to our customers on occasion. They sometimes refer to the service as Infinity (as they did in this case), and have even been known to refuse to install a service because a customer does not have a BT Home Hub.

I think this is the first case where they have said that the customer should get a BT Home Hub when repairing a fault. Oh, and it is not clear that they did int fact repair the fault in this case either.

It makes us look stupid and is very anti-competitive.

Zero packet loss

I was pondering the concept of a zero packet loss service, following some comments on a post in ispreview. The commenter was adamant that it is impossible to provide a zero packet loss service. Of course, this was silly anyway as what we claimed is that the Ethernet service allowed us to do zero packet loss maintenance on our routers, which is not the same thing at all.

But I was pondering what was meant by a zero packet loss service anyway.

Zero is a problem, for a start. With a lot of metrics that one is trying to achieve in a service, one can design the service to exceed the require metric by more than any margins of error so as to guarantee you achieve it. When talking of zero loss, you can't do that - there is no way to have better than zero loss, in there? So one is working against a brick wall of a target. This means you have to define a tolerance or carefully define the measurement parameters.

The closest one could consider the services we offer to zero loss would be a point to point uncontended link. These used to be bare fibre with termination equipment (WES), but these days such links are switched at the exchange (EAD). Either way, if one has a 100Mb/s uncontended point to point Ethernet link, then that can be zero packet loss as a service. Any packet you put in one end will come out of the other end. Obviously, if you want to send 101Mb/s on a 100Mb/s link then it won't work, but it won't be the service which is dropping packets. In that case it will be your switch or computer trying to send more data that has to delay the data or drop packets in order to get what it is sending down a 100Mb/s interface. The service can be zero packet loss.

Is it really zero though? Well, the problem is that any outage whatsoever, any time, ever, in the life of the service, even for a microsecond, means the service is not zero packet loss any more. So actual zero is probably impossible. It has to be zero packet loss (when the service is working), and then have caveats on repair times for when it is not. But, within normal tolerances of Ethernet links, one can offer a zero packet loss service.

Better than zero? There is also the risk that a stray particle flips a gate on a receiver somewhere and a bit is received wrongly so a packet dropped. Interestingly, the newer standards for Ethernet at very high speeds have error correction, just like disk drives and indeed many communications systems these days. So actually, you end up with a case that packets get through even with a specified level of interference in the medium. In a way, this is making a system that is better than zero, in that it is still zero loss in the face of certain levels of error. Normal EAD links don't have this, but I think the FTTC VDSL does have it in some configurations, which means stating zero loss is more feasible. Sadly the FTTC is normally a shared link back-haul to the exchange, so contended, and so not something we would sell as zero loss anyway. In the future, more and more links will have inherent error correction.

Internet services are a tad special in that Internet access is never uncontended or zero loss. We can (and do) have services that are zero loss uncontended links from customers to us, and then we connect on to the Internet. Transit providers can (and some do) offer zero loss guarantees over their transit network, and even compensate if that is not the case. But that is to their border only. The very nature of the Internet means packets to a specific end point could be lost due to congestion on a link. Thankfully we don't try and offer zero loss services over the Internet, obviously.

Zero packet loss router maintenance is what we actually claimed. This is much easier, and even industry standard. The principles are very simple indeed - you have more than one path the traffic can take (in each direction), and you ensure that traffic is switched from one path to another, so as to allow one bit of equipment to be worked on when it is carrying no traffic.

There are several means to do this, including routing protocols like BGP and OSPF, or low level protocols like VRRP. Virtual Router Redundancy Protocol is mainly used for fall-back, i.e. if something breaks, and can react within as little as 30ms (with version 3). However, if can be used to manage which is the active router as a deliberate step as part of router maintenance. With the FireBricks we have a built in controlled shutdown and startup sequence which means VRRP and BGP both actively change incoming traffic to the other router before rebooting to run new code. The reboot is well under a second, and the startup is sequenced to ensure we have routing for traffic before taking over as master again.

Whatever the technique, the trick is switching the traffic from one router to another. With routing protocols, this is part of the protocol itself - you simply change what you announce. With VRRP the switching means a different device becomes master, and it uses the VRRP MAC address to convince a switch to change where it sends packets for that MAC.

In either case you want the old router to still accept and forward traffic during the switch over. This means that the sending end can take what time it needs to do the switch. At no point is the sending end unsure where to send a packet, it is always either the old router or the new. Whichever it sends to, the packet is sent on to where it needs to go.

The means that no matter how faster the packets are flowing, no packet is lost by the switch over process. There is no fine timing and co-ordination required, as the old router can accept traffic for as long as necessary (seconds even) before the sending end switches over.

Once traffic is switched off the old router it is no longer involved, and so can be worked on, rebooted, upgraded, or whatever.


So, I stand by our claim that we can do zero packet loss maintenance on our routers for our Ethernet services.