from a to b… to IT

What a week, today is a bank holiday and I should be enjoying this rare treat but unfortunatly I’m spending it trying to jump start all manner of connections back in to life.

Anyway my headache of the week has been trying to decipher the differences between a channalized and unchannalized E1 service… not as easy (or as documented) as you might think!

E1 (Unchannelised).

A unchannelised E1 is exactly that, an E1 line but with no channels present on it. Usually an E1 is presented with 31 channels, this is not.

A unchannelised E1 is also known as an unstructured E1, clear channel, 2Mbit E1, full E1 etc… you get the idea! To support this service on our friendly Cisco 3845 (and indeed any of the other ISR range) you’ll need a VWIC-1MFT-G703. Note the G.703 bit on the end, required for unchannelised E1 support! Also note that on this circuit you will need to provide the clocking, clock from your router on one end and then from the line at the other.

To configure this on a Cisco router use the following:

! Firstly tell the router its an E1 card
! and then select the clock from it to stop skew issues.
!
card type E1 0
network-clock-participate wic 1
network-clock-select 1 E1 0/1/0
!
! Create an unframed channel group, this will use the full 2Mbit
!
controller E1 0/1/0
channel-group 0 unframed
!
! Issuing the above will create a serial interface
!
Serial0/1/0:0
ip address 10.0.0.1 255.255.255.0
!

Job done, you will have a 2Mbit unchannalized E1 service.

Channelised E1

Also known as structured E1, 1984k. This service will not work with the G703 card. For this you can use any voice/wan interface that supports E1. Another feature of this circuit is that the clock will come from the network at both ends.

To configure this on a Cisco router:

! Firstly tell the router its an E1 card
! and then select the clock from it to stop skew issues.
!
card type E1 0
network-clock-participate wic 1
network-clock-select 1 E1 0/1/0
!
! Create a channel group using all timeslots, this will use only 1984k of the channel.
!
controller E1 0/1/0
channel-group 0 timeslots 1-31
!
! Issuing the above will create a serial interface
!
Serial0/1/0:0
ip address 10.0.0.1 255.255.255.0
!

Note the subtle difference with the controller command. This will create a 1984k channelised E1 service.

Right I’m glad thats cleared up! Make sure when your ordering your E1 link your very clear on how you want your circuit delivered.

Normal service should resume this week…

Have you ever had one of those weeks that just drags and drags, this has been one of them for me. Hopefuly normal service will resume at some point!

A couple of new toys that caught my eye this week…

Freesat Boxes in the wild!

It appears we are merely days away from the launch of the new free to air satellite service from the BBC and ITV. I’m looking forward to this as our freeview coverage isn’t that great and I’d like to get my hands on some HD tv for free!

No paying Sky umpteen million pounds a year for 500 channels that I wont watch, just some nice crystal clear BBC, ITV and CH4. Channel 5, get in to gear and get yourself on this platform!

Draytek Vigor 2820Vn

Not the cheapest router by a long way! But the new Draytek Vigor 2820Vn does seem to tick all the right boxes, especially with the included voip capabilities including FXO meaning calls can be made and recieved over the traditional PSTN as well as VoIP. I’ll be picking one of these up soon!…

Also I was flicking through Apple Trailers and noticed a few films with potential… 21, Bangkok Dangerous and Tropic Thunder are all on my to watch list.

Well my friends, it appears that you all want more information regarding configuring ISDN lines and SRST mode on the Cisco 3845!

Not the most fun of subjects but something very important, especially as the 3845 is designed to be a branch router or dedicated voice gateway.

Sit tight… I’ll try and get something written up over the weekend.

What a week, I’ve worked 70 hours so far… a lot of it on getting our modem dialback system to work!.

So I use a Cisco 2811 loaded with a WIC-1AM-V2 and a Async card also to provide remote console access to our devices, thus if all the wan circuits drop theres still another way in!

The problem I’ve had this week is that the modem just would not dial, it refused, the only error message I got was “Async 0/2/0 reset by async dial out failure” (or something along those lines). I suspected that the telco was either delaying the sending of dialtone or was sending a stuttered dialtone (e.g. with message waiting).

The best way to troubleshoot this is to telnet straight to the modem and issue AT commands to it to see if you can force a dial out. This will check the modems working ok:

Firstly you need to find out what line your modem is operating on, do a sh run | include 115200. This should only show the modems you have in the system. In this example I’m going to use line 50.

Next, telnet to the terminal server on line 50, e.g. telnet 192.168.0.249 2050. If you’ve put a password on your lines then you’ll need to enter it. You should then be left with nothing, to check you’ve sucsessfully connected to the modem type: AT, the modem should respond with OK.

Now attempt to dial out:

AT
Modem responds: OK
ATZ
Modem responds: OK
ATDT\T<00441494123321>

If there is a problem with the dialtone it will respond: NO DIALTONE

To try again, this time without waiting for a dial tone:
AT
Modem responds: OK
ATZ
Modem responds: OK
ATX3
Modem responds: OK
ATDT\T<00441494123321>

If you have connected successfully you’ll see:
CONNECT 115200/V92/LAPM/V44/28800:TX/46667:RX

Bingo! So now we need to tell the 2811 to do this every time to dial out. The way we can do this is with a chat script. Modemcap is a possibility but the “default chat script” will reset the modem after the modemcap has happened so we can’t use modemcap.

From global config mode:
(config)#chat-script nodialtone “” “ATZ” OK “ATX3″ OK “ATDT\T” TIMEOUT 60 CONNECT \c

(NOTE: We don’t need to put the phone number in there, Cisco will handle that!)

Then apply the chat-script to the modem line (in this case line 0/2/0):
(config)#line 0/2/0
(config-line)#script dialer nodialtone.

Now when you dial out using a dialer on that interface it will run that chat script. Problem solved!

To debug this lot use: debug modem, debug chat, debug async state, debug dialer.

Hopefully you won’t loose as much hair as me over this!

Weekend was spent back down in Plymouth for a friends birthday… an excellent night in which we went to the Plymouth Gin distillery cocktail bar.. (I didn’t even know they had one!). This building (according to wikipedia) has been there since the late 1400’s and it certainly showed with an amazing vaulted ceiling.

Unfortunatly my pallet doesn’t agree with gin but others in the party said the cocktails were some of the best they’ve had in ages. The cocktail bar appears to be a members only place (however we blagged our way in) so it might be worth going down there on a weekday and signing up!

To round off the weekend when I got back from Plymouth this was sat on my desk:

My new Hofbrau beer boot. My classic 0.25l was was smashed by a housemate but this 0.5l is very very sturdy and I hope should last me for a while!

Beer of the weekend was Staopramen, a very nice Czech pilsner, highly recommended!.

Well as soon as I suggest that people start thinking out of the box on datacenter design, what happens?… some people I know have decided to update their datacenter strategy to include..

- Recycling of warm air to heat the rest of the building

- Forced cooling with positive underfloor pressure and a hot air return via a false ceiling

Two steps closer to a better datacenter, however they let themselves down by telling me that they are going to fill it full of super energy efficient computers when I know they’ll be using the most power hungry blades they can find! C’est la vie!

In other news the Red Bull Flug Tag is back! Book your tickets here! Watch the idiots throw themselves in to the serpantine in Hyde Park, London… it’s going to be good

Also discovered the excellent PHP based Network Weather Map - available here - which I’m going to have a bash at integrating at work. It allows you to create a network map where interlinks are represented by arrows that change colour based on link utilization. I can see it being a great use in identifying hotspots, I also think you could use it to provide visual traffic forecasts by incrementing the link usage by a multiplier; e.g. if you wanted to budget for a doubling in traffic simply double all the values and regenerate the map.

Well well, the lovely people at Be* have finished upgrading my broadband service from Demon. What makes it even more lovely is that even though I only ordered thier “Lite” 8Mbit service they appear to have enabled the full 24Mbit service!

Now as we all know no one can ever get 24Mbit unless you live in a telephone exchange, I can’t imagine that would be nice with the constant noise of air conditioning… but I’m currently connected at 17Mbit and enjoying every moment of it! Thanks Be*!

In other news it appears that someone is thinking outside the box when it comes to Datacenter cooling: Those crazy Swiss types are using the excess heat from their datacenter to heat the local swimming pool! Good work people.

Anyway it’s Friday.. welcome to the weekend!

Sorry it’s been a quiet few days on here, it’s been a busy week for me in Real LifeTM. This week I have completed my CVOICE training which means i’m on the path to becomming a Cisco Certified Voice Professional (CCVP). I’ve got this exam and my F5 exam comming up shortly so need to hit the books!

Anyway my friend over at fluxbox.co.uk took some fantastic panoramic pictures of Plymouth Hoe, for those that haven’t experienced this first hand it’s amazing in the summer to go there and relax. Check out one of his panoramic photos spanned across my monitors below: 

Also, if you haven’t checked out my mate “Bedders” blog then do it!, we always said “put it in the podcast”, but he’s chosen the forgotten art of writing to air his views… he’s also throwing in some recipes for good measure.

Another Saturday, another day at work having fun with the fleet of Cisco devices that I manage.

Todays candidate: Cisco 3845 ISR Router - I must admit this is a pretty decent piece of kit, a single box solution that does all the normal networking and WAN connectivity but also can operate as a simple PBX and a voice gateway. Pop a ISDN card in, slap on a voice config and your laughing (or not!).

Tip of the day…If your ISDN PRI just doesn’t want to come up (and the endpoint won’t register in call manager) check the following.

1) Do:

debug isdn q921

If your circuit is in good shape you should see lots of debug mentioning that it wants to come up. You can also check by doing

sh isdn status

You’ll see that it’s sat in “TEI_ASSIGNED” mode.

2) shut/no shut your PRI. This will force it to go down and back up, this can sometimes bring it back in to life.

3) If all else fails then:

no mgcp

mgcp

This will force the gateway to pull down a config from the call manager and usually this will make the PRI register.

4) To check it’s registered do:

sh isdn status

You should see it in “MULTILINK_FRAME_ESTABLISHED” mode, this is expected behavior. To check calls are passing correctly do a: debug isdn q931. If you make some test calls you’ll see the traffic coming in and out. Remember to see this output you’ll need to do a term mon and remember once you’ve finished to do a no debug all!

Lunch time I think… and who stole my hour of sleep this morning!

I only keep two primary e-mail accounts, my personal and my work, but between them I was having to trawl through a mountain of e-mail, twice, daily. My inbox was overflowing with all kinds of e-mails, stuff I was going to do sometime but forgot.. it was taking me ages to find what I was looking for… then along came GTD. 

GTD (getting things done) is methodology for organising your life, tasks and e-mail in to manageable work chunks and prioritising accordingly. It has a defined labelling system and associated heirarchy. Whilst this might of been great if I’d adopted this in the beginning, it’s quite hard to retrofit an organisation system, just like trying to retrofit air conditioning or heating in your house, it creates a lot of mess and everyone gets annoyed. 

So I chose to simply become ruthless… if it had no immediate use it was trashed, not archived, trashed. E-mails that contained important information (defined as billing, accounting) was archived. That was it, no stupid chain e-mails, pictures of cats…. all gone. 

Now my inbox (both at home and work) is a crystal clear workspace, the only e-mails that are stored are ones that I’m currently actioning, and even then I don’t store whole conversations… what’s the point when it’s already tagged on to the bottom of the e-mail.

My workflow and productivity has improved and I’ve found I can actually find information faster because any information I do have I’ve had to think about and file away.

Perhaps it’s time you gave your inboxes a little spring clean!