downloading on a t1 connection

gaby_978

hey guys. dont know if this is the right place to post but here it goes.


I've been working a trouble ticket here at work (isp provider). Well the t1 is up/up and passing traffic fine. No errors, no drops, no bounces. Everything seems to work fine. Customer is complaining that when he tries to download a file it slows down the whole network. While i was working wiht the cust over the phone i saw the load on the serial to be around 25/255 and as soon as he started downloading a file I saw the link almost maxed out.

I explain to the cust that this is happening because the serial is trying to use as much bandwidth as it can to download the file therefore the utilization is going up. Cust said this wasnt the case before and he doesn't understand why this is happening now.

Anyway the ticket is amolst in the process of beign escalated becasue of duration.

Can someone please give a clear explanation of why this is happening?

Thank you

tech-airman

gaby_978 wrote:

hey guys. dont know if this is the right place to post but here it goes.


I've been working a trouble ticket here at work (isp provider). Well the t1 is up/up and passing traffic fine. No errors, no drops, no bounces. Everything seems to work fine. Customer is complaining that when he tries to download a file it slows down the whole network. While i was working wiht the cust over the phone i saw the load on the serial to be around 25/255 and as soon as he started downloading a file I saw the link almost maxed out.

I explain to the cust that this is happening because the serial is trying to use as much bandwidth as it can to download the file therefore the utilization is going up. Cust said this wasnt the case before and he doesn't understand why this is happening now.

Anyway the ticket is amolst in the process of beign escalated becasue of duration.

Can someone please give a clear explanation of why this is happening?

Thank you

gaby_978,

What other kind of traffic is moving across that T1 link? In particular, which other application(s) is/are more notceably slow at the time the customer is performing a file transfer?

Mishra

Can you try to throttle his bandwidth usage to 200kb or so and then ask him to download a file and see if it effects anything?

gaby_978

What other kind of traffic is moving across that T1 link? In particular, which other application(s) is/are more notceably slow at the time the customer is performing a file transfer?

Customer says there is normail internet traffic. no other download. As far as which other application are slowing down, is the circuit. I do see utilization of the serial on the PE router go up almost to the point of maxing out the T1.

gaby_978

Mishra wrote:

Can you try to throttle his bandwidth usage to 200kb or so and then ask him to download a file and see if it effects anything?

I have no control of his bandwdth usage. One thing I suggested was to try plugging a laptop to his router and perform the download from there, eliminating all internal traffic, but he states ha cannot do that.

tech-airman

Mishra wrote:

Can you try to throttle his bandwidth usage to 200kb or so and then ask him to download a file and see if it effects anything?

Mishra,

T1 by definition is a "leased line" type of WAN link. As such, the lessee has full rights to full bandwidth. Any attempt at throttling bandwidth may violate the terms of the lease and possibly lead to a possible civil case by the lessee against the lessor regarding breach of contract. With that said, the situation is that it seems like there's a "lack of bandwidth" issue already so to reduce it further to 200 kbps isn't likely to help.

tech-airman

gaby_978 wrote:

What other kind of traffic is moving across that T1 link? In particular, which other application(s) is/are more notceably slow at the time the customer is performing a file transfer?

Customer says there is normail internet traffic. no other download. As far as which other application are slowing down, is the circuit. I do see utilization of the serial on the PE router go up almost to the point of maxing out the T1.

gaby_978,

So how exactly is the customer experiencing/perceiving that the network is "slow?"

larkspur

tech-airman wrote:

Mishra wrote:

Can you try to throttle his bandwidth usage to 200kb or so and then ask him to download a file and see if it effects anything?

Mishra,

T1 by definition is a "leased line" type of WAN link. As such, the lessee has full rights to full bandwidth. Any attempt at throttling bandwidth may violate the terms of the lease and possibly lead to a possible civil case by the lessee against the lessor regarding breach of contract. With that said, the situation is that it seems like there's a "lack of bandwidth" issue already so to reduce it further to 200 kbps isn't likely to help.

i believe this can be accomplished by using a route-map and acl for that one host and will not violate any agreements.

something like this
access-list 10 permit host x.x.x.x

class-map match-any SpecificHost
match access-group 10

policy-map SqueezeHost
class SpecificHost
police 128

interface e0/0
service-policy input SqueezeHost
service-policy output SqueezeHost

phreak

Are you guys tracking the T's 95th percentile average 8-hour daily?

How about the 95th 5-minute average? How are those looking?


If those are pretty constant at coming close to the 1.5/1.5 I'd say it's time to add another T, or tell the customer to put some traffic shaping methods into place on their network.

tech-airman

gaby_978,

gaby_978 wrote:

What other kind of traffic is moving across that T1 link? In particular, which other application(s) is/are more notceably slow at the time the customer is performing a file transfer?

Customer says there is normail internet traffic. no other download.

What kind of "normal internet traffic?" web? e-mail? ftp? online audio/video? other?

gaby_978 wrote:

As far as which other application are slowing down, is the circuit. I do see utilization of the serial on the PE router go up almost to the point of maxing out the T1.

What do you mean by "PE router?"

Mishra

tech-airman wrote:

Mishra wrote:

Can you try to throttle his bandwidth usage to 200kb or so and then ask him to download a file and see if it effects anything?

Mishra,

T1 by definition is a "leased line" type of WAN link. As such, the lessee has full rights to full bandwidth. Any attempt at throttling bandwidth may violate the terms of the lease and possibly lead to a possible civil case by the lessee against the lessor regarding breach of contract. With that said, the situation is that it seems like there's a "lack of bandwidth" issue already so to reduce it further to 200 kbps isn't likely to help.

I'm not saying throttling the entire T1 line. Just that particular user. Setting up some ACL on the firewall/router to restrict by his IP.

gaby_978

PE router meaning the the isp router. I dont have access to the customer router at all.
Not sure exactly what type of traffic the customer consider normal. when i asked him for the type of traffic he had on the circuit he just said normal everyday traffic.

Is there a way of the customer prioritazing bandwidth for whateva type of traffic he is using? meaning can the cust say when downloading a file I dont want to use all availabel bandwidth but only certain percentage. See whats happening is tha whenever he starts a download the link will use all available bandwidth therefore cosuming almost the entire link

gaby_978

tech-airman wrote:

gaby_978 wrote:

What other kind of traffic is moving across that T1 link? In particular, which other application(s) is/are more notceably slow at the time the customer is performing a file transfer?

Customer says there is normail internet traffic. no other download. As far as which other application are slowing down, is the circuit. I do see utilization of the serial on the PE router go up almost to the point of maxing out the T1.

gaby_978,

So how exactly is the customer experiencing/perceiving that the network is "slow?"

he start seeing latency across the link and starts dropping packet, which is happening becasue the link runs at over 90% capacity when he starts downloading a big file.

tech-airman

gaby_978 wrote:

tech-airman wrote:

gaby_978 wrote:

What other kind of traffic is moving across that T1 link? In particular, which other application(s) is/are more notceably slow at the time the customer is performing a file transfer?

Customer says there is normail internet traffic. no other download. As far as which other application are slowing down, is the circuit. I do see utilization of the serial on the PE router go up almost to the point of maxing out the T1.

gaby_978,

So how exactly is the customer experiencing/perceiving that the network is "slow?"

he start seeing latency across the link and starts dropping packet, which is happening becasue the link runs at over 90% capacity when he starts downloading a big file.

gaby_978,

Latency while doing what? Watching YouTube videos? Listening to online music/radio stations? Web downloading and what type of file is being downloaded? FTP downloading and what type of file is being downloaded? Other?

APA

tech-airman wrote:

gaby_978,

gaby_978 wrote:

What other kind of traffic is moving across that T1 link? In particular, which other application(s) is/are more notceably slow at the time the customer is performing a file transfer?

Customer says there is normail internet traffic. no other download.

What kind of "normal internet traffic?" web? e-mail? ftp? online audio/video? other?

gaby_978 wrote:

As far as which other application are slowing down, is the circuit. I do see utilization of the serial on the PE router go up almost to the point of maxing out the T1.

What do you mean by "PE router?"

PE - Provider Edge (Normally at exchange or within providers premises.. Last hop before reaching CE router)

CE - Customer Edge (The edge of customer network last hop before entering Providers network)

What site is he downloading from.. .What size is the file....

QoS configured on the router? Something is triggering the router to give that specific download max bandwidth.....

Has he tried downloading a different file???

gaby_978

PE - Provider Edge (Normally at exchange or within providers premises.. Last hop before reaching CE router)

CE - Customer Edge (The edge of customer network last hop before entering Providers network)

What site is he downloading from.. .What size is the file....

QoS configured on the router? Something is triggering the router to give that specific download max bandwidth.....

Has he tried downloading a different file???[/quote]

He first was downloading a 400meg file than he tried a 20 meg file. Cust doesnt have QoS and he was downloading from microsoft.com dont know exactly what.

flipmad

So he is running 90% of the bandwidth? of course he is going to see latency on the T1. If he is maxing out the bandwidth he is bottlenecking the traffic. As an ISP do you have utilization stats, IE: SNMP that can confirm the amount of bandwidth they are utilizing? Is this a Leased line T1 CAS or a Frame Relay T1?

Im from Tampa by the way. How is the orlando job market treating you?

gaby_978

blake15 wrote:

So he is running 90% of the bandwidth? of course he is going to see latency on the T1. If he is maxing out the bandwidth he is bottlenecking the traffic. As an ISP do you have utilization stats, IE: SNMP that can confirm the amount of bandwidth they are utilizing? Is this a Leased line T1 CAS or a Frame Relay T1?

Im from Tampa by the way. How is the orlando job market treating you?

it is not a frame. just a regular T1. He only runs over 90% once the download a a file starts, before that the utilization is about 20% or so. All i can see from my side is the % of the cust input.

larkspur

How many users behind the T1?

ok it is obivous that the file transfer is over utlizing the T1.

If you could post the config sanitized that woulod be cool.

also you can rate-limit this host so the circuit does not get like this.

access-list 10 permit host x.x.x.x

class-map match-any SpecificHost
match access-group 10

policy-map SqueezeHost
class SpecificHost
police 128

interface e0/0
service-policy input SqueezeHost
service-policy output SqueezeHost

Aaronfb

What speed to they see the file transfer happening at? It's unlikely that they are getting a full 1544kbps connection to microsoft.

Maybe have them test the connection with speedtest.net and see what kind of speeds they are getting.

gaby_978

larkspur wrote:

How many users behind the T1?

ok it is obivous that the file transfer is over utlizing the T1.

If you could post the config sanitized that woulod be cool.

also you can rate-limit this host so the circuit does not get like this.

access-list 10 permit host x.x.x.x

class-map match-any SpecificHost
match access-group 10

policy-map SqueezeHost
class SpecificHost
police 128

interface e0/0
service-policy input SqueezeHost
service-policy output SqueezeHost

configs are as follow
SerialXXX
ip address x.x.x.x x.x.x.x
ip verify unicast source reachabel-via rx allow-self ping 108
no ip proxy-arp
no ip mroute-cahce
load-interval 30
no cdp enable
end
==============================================================
then we have one route for him
==============================================================
That's it. He sits in one of our gateway routers. All we do is provide him with internet connection. We dont manage his equipment and he doesnt have any firewall serives with us

gaby_978

Aaronfb wrote:

What speed to they see the file transfer happening at? It's unlikely that they are getting a full 1544kbps connection to microsoft.

Maybe have them test the connection with speedtest.net and see what kind of speeds they are getting.

He is using a program called bandwidth meter which is telling him that the speed is 150/kbps.

tech-airman

gaby_978 wrote:

Aaronfb wrote:

What speed to they see the file transfer happening at? It's unlikely that they are getting a full 1544kbps connection to microsoft.

Maybe have them test the connection with speedtest.net and see what kind of speeds they are getting.

He is using a program called bandwidth meter which is telling him that the speed is 150/kbps.

gaby_978,

Can you make sure of the units of that performance? Lowercase 'k' stands for 1000. Uppercase 'K' stands for 1024. Lowercase 'b' stands for bits. Uppercase 'B' stands for Byte which is 8 bits. Therefore, kbps is not the same as KBps. So that performance figure can be as low as 150,000 (150 x 1000) bits per second and as high as 1,228,800 (150 x 8 bits/Byte x 1024) bits per second.

Questions:

1. Since you mention T1, do you have an internal or external CSU/DSU?
2. Does your customer have an internal or external CSU/DSU?

mgeorge

First off, a t1 isnt that much bandwidth any more, as media and programming has changed, so
has the requirement of bandwidth. If this customer is using a T1 just for internet then this is
a horriable design, i would have deployed aDSL or cable for end user browsing, and leave the t1
to back end management, servers, vpn etc..

Sounds to me like QoS is in order...

gaby_978

We finally close this ticket today. The program the cust was using was giving him the resutls in kilobytes per second instead of bits per second, so the cust thougth he wasnt using the entire bandwidth for the download. He kept thinking that he had bandwidth left. We had to explain him that if the bandwidth meter program he was using said he was using 150 bytes he was actually using 1.2 meg.


Thank You all for your great responses.

cisco_trooper

Does the customer know that a T1 is ONLY a T1?

Most people have better download speeds at home. Just sayin'....

KGhaleon

[edit]

mgeorge

Thats probably one of the worst design flaws in networking >.<

Lots of people dont know the difference between Megabits and Megabytes
I'm talking end users, not IT professionals


When people think oh im getting a 1.544Mbps down/up
they always like to think thats in "megabytes" little do they know they need
to divide that number by 8 lol (1536/8=192KB Per/Second)

phreak

Indeed Mgeorge.




I get calls all the time from customers thinking they are having speed problems. The clowns always are referencing the wrong numbers, so i must explain exactly how things work.



Glad you got the ticket closed.

Kalabin

I really don't understand why company's purchase a leased line that end's up being used for internet traffic. As stated above aDSL can now reach spead's of 20Mbps with a ADSL2+ card in the CO DSLAM. The company im working with is experimenting with port mirroring with copper pair's on a DSLAM to give a estimated bandwidth of over 40Mbps over standard copper pair's.

If it's a point-to-point connection to a branch office then it makes sense, but for the cost of a leased line to use it for internet is a huge waste of coin.

lildeezul

Whats the normal download speed of a T-1 internet connection