Bonded T1s

Unanswered Question
May 11th, 2009

Hi all,

I would like to know how to configure a single T1 DSU/CSU connecting to a single circut but the service provider is provisioning 2 T1/bonded ckts?

Thanks in advance,

sK

I have this problem too.
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John Blakley Mon, 05/11/2009 - 11:01

If you only have one port on your T1 card, you won't be able to use the second circuit. You'll need to either get another card with a single port, or replace your existing card with a dual port card. If you already have that, then you can configure a multilink bundle:

int s0/0

no ip address

encaps ppp

ppp multilink

ppp multilink group 0

int s0/1

no ip address

encaps ppp

ppp multilink

ppp multilink group 0

int multilink0

ppp multilink

ppp multilink group 0

ip address 5.5.5.5 255.255.255.0 <-provider assigned IP address

HTH,

John

skhirbash Mon, 05/11/2009 - 12:14

Thanks John. That's was my thinking too; however, the service provider is only bringing one cable(one jack) to premises but stating that the CKT is a bonded T1 (Point To Point). So, that's why I have a single T1 DSU/CSU module in place to plug the single ckt in. Is the service provider misleading me or is there another way of configuring the single T1 to use bonded T1s?

Thanks in advance,

sK

John Blakley Mon, 05/11/2009 - 12:23

Are they bonding them on their end? What you might try is configure one serial interface, and then do a bandwidth speed test to see if you're getting +3Mb.

I don't know of any other way to bond the T1 line because, in my experience, it's usually done at the router end unless the provider is doing something.

HTH,

John

skhirbash Mon, 05/11/2009 - 12:26

I think that bonding is occuring on the service provider's end. Out of curiosty, how would I perform a bw speed test from the router?

Thanks,

sK

John Blakley Mon, 05/11/2009 - 12:28

Not from the router, but from a host behind the router. There are a ton of sites out there that can tell you what your up/down speed is.

John

ilnaiduccna Mon, 05/11/2009 - 23:21

Hi John,

Sorry for the middle interupt but it is so interesting.

As you said about bandwidth speed test to see if you're getting +3Mb.

Can you just help me out how we can check the bandwidth speed, is it from router or any other devices we need.

Regards,

Naidu.

ilnaiduccna Tue, 05/12/2009 - 02:31

Hi Rajesh,

Thanks for your response.

Could you just tell me clearly and give the proper step by step to check BW.

Note: I need to know how much BW i am getting from Provider.

Regards,

Naidu.

skhirbash Tue, 05/12/2009 - 07:05

Hi John,

What would the proper way to configure the singel serial interface for a Point-to-Point type of service?

Tx,

sk

John Blakley Tue, 05/12/2009 - 07:16

That depends on the provider. They would provide you an address, and then you'd put it on your serial interface with the proper encapsulation. By default, serial interfaces use hdlc encapsulation. The provider will tell you if it's frame-relay or hdlc.

HTH,

John

skhirbash Tue, 05/12/2009 - 11:12

Thanks John.

I found out that the type of service we are getting is an at&t MIS type of service. So, I think that the ppp would be the encapsultion used in this case, correct?

Tx,

sK

John Blakley Tue, 05/12/2009 - 11:14

Ah. I believe so. They should be able to help you with the settings. We're switching over the MIS also to a 20mb line. :)

John

skhirbash Thu, 05/14/2009 - 13:58

Hi John,

In the BW statement under outbound interface, what should be the BW configured for a bonded 2 T1s?

Thanks,

sK

skhirbash Thu, 05/14/2009 - 13:59

Hi John,

In the BW statement under outbound interface, what should be the BW configured for a bonded 2 T1s?

Thanks,

sK

John Blakley Thu, 05/14/2009 - 14:20

If you only have the one connection coming in, you can do 3088 (1544*2). The only this does though is to provide a calculation with certain routing protocols and bandwidth measurements. It won't control speed, so if they're really only pushing 1 T (1.5Mbps), then you won't see 3MB even if you set it on the interface. Does that make sense?

John

skhirbash Thu, 05/14/2009 - 16:15

Yes, it makes sense; however, they are promising 2xT1 (bonded CKTs)but with only a single cable which will be connected to the CSU/DSU! Now, will be receiving 3088 or 1.54Mbps, that will be put to the test once the ckt is up. So, you I will configure the interface with 3088.

Thanks again John,

sK

skhirbash Thu, 05/14/2009 - 16:15

Yes, it makes sense; however, they are promising 2xT1 (bonded CKTs)but with only a single cable which will be connected to the CSU/DSU! Now, will be receiving 3088 or 1.54Mbps, that will be put to the test once the ckt is up. So, you I will configure the interface with 3088.

Thanks again John,

sK

Paolo Bevilacqua Fri, 05/15/2009 - 11:25

No, that does not makes sense, because it is impossible to give a 3mbps service using a single T1 interface that only runs at 1.5 mbps.

And you cannot "configure the interface with 3088".

So, either they will give you a enthernet interface, or two physical T1 interfaces.

John Blakley Fri, 05/15/2009 - 11:38

impossible to give a 3mbps service using a single T1 interface that only runs at 1.5 mbps.

Agreed. But when the OP said "bonded T1s" that's how this thread got started.

I disagree on your second statement. Yes you can: (It's just for calculations)

interface Serial1/0

bandwidth 3088

no ip address

end

will give you a enthernet interface, or two physical T1 interfaces.

Ethernet possibly. Maybe they'll receive a device that bonds the two at their location and they'll connect to a switch from their router which is highly possible. I think the provider should step in and tell them exactly what needs to be done though. Seems that there's a lot of "in the air" stuff from AT&T.

John

jgreenwoodii Fri, 05/15/2009 - 11:55

Technically is would be 3072, But I'm pretty sure it's managed based on the email from AT&T. He will use the Ethernet port on his router and set the proper IP/Mask and Default GW. Very simple setup. He may have to run the Ethernet cable from the Demarc to connect the circuit into AT&T router if they don't go out there to physically set it up.

HTH

Jonathan

Paolo Bevilacqua Sat, 05/16/2009 - 23:07

I disagree on your second statement. Yes you can: (It's just for calculations)

interface Serial1/0

bandwidth 3088

no ip address

If you do this:

1. the physical behavior or spred of the interface will NOT change.

2. anything based on interface speed, as simple as an smnp graph will be wrong.

So, don't change bandwidth parameter to thing different from reality.

Patrick Laidlaw Fri, 05/15/2009 - 18:26

So is this csu/dsu being provided and are you useing a Wic-1t or are you using a WIC-T1-DSU? If your using a wic-1t its conceivable that you would be able to get a higher bandwidth than 1.544.

skhirbash Sat, 05/16/2009 - 18:39

Thanks for the response. I didn't know there was a difference btwn the two WICs since T1 data rate is known to provide 1.54Mbps. Are there any docs to show the difference?

Thanks, SK

Paolo Bevilacqua Sat, 05/16/2009 - 23:10

There is no difference. The presence of a internal or external DSU does NOT change the circuit speed of 1544 kpbs, of which 1536 are available to hdlc / ip.

skhirbash Thu, 05/14/2009 - 16:15

Yes, it makes sense; however, they are promising 2xT1 (bonded CKTs)but with only a single cable which will be connected to the CSU/DSU! Now, will be receiving 3088 or 1.54Mbps, that will be put to the test once the ckt is up. So, you I will configure the interface with 3088.

Thanks again John,

sK

jgreenwoodii Fri, 05/15/2009 - 10:41

Sounds like it will be a managed service. Meaning they will place an Cisco 1841 router at your location to terminate the circuits and handoff to you on a LAN port. That's what I take from the Single Cable deal. Can you verify if they are providing a router or not to terminate the circuits?

HTH

Jonathan

skhirbash Fri, 05/15/2009 - 10:47

Hi Jonathan,

No, this will not be a managed service. We have our own 2851 router with a new T1/CSU-DSU module that I installed last week.

Here is a snapshot of thread of emails btwn me and at&t rep:

From: at&t rep

To: Me

Correct. The only thing you will have to do, concerning the equipment, is make sure the modem, router, and circuit are connected properly and powered on.

-------------------------------

From: Me

To: at&t rep

Subject: RE: AT&T: Customer Advisory Letter: Ready for Test & Turn up

I am assuming that the bonding of the T1s is done on your end but not on our end, meaning, if there is only one physical ckt (single cable) being provided and we are plugging this single cable into a single T1 DSU/CSU module, we aren't doing any bonding on our end. Would this be accurate?

Thanks in advance,

sK

jgreenwoodii Fri, 05/15/2009 - 10:59

It is managed based on the email from AT&T telling you to make sure the "modem, router, and circuit are connected properly and powered on."

Usually they will ship out an Cisco 1841 Router with a US Robotic modem so they can manage it. You will connect to their router off of your LAN port on your router to the LAN port on their router.

Based on this email that's what I gather.

HTH

Jonathan

skhirbash Fri, 05/15/2009 - 13:55

Well, currently we have a DSL line so she is talking about having this modem connected. My confusion is why the rep mentioned having the modem ready if we are getting a T1 CKT that will be connected directly to the CSU/DSU module!

Tx,

sK

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