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New Member

Max bandwidth WIC-1T

Been trying to figure out this problem we are currently having and I think that maybe *crosses fingers* I found a lead. The problem is we are periodically having voice and data drops in the line. The interfaces are not reporting the service faults and actual drops though, the interfaces still stay up through out the problem. I do think the problem correlates directly to how much traffic is being pushed across the wire. I think what is happening is we are overloading the WIC-1T card.

We have a 3640 with 2 Network modules installed. 1 module is a NM-FE-PRI 1FE-2CT1-CSU. The other network module is a NM-1FE-2W and has a WIC-1T serial interface installed. The way our router works is the 2 T1s come into the 2 T1 ports on the 1FE-2CT1-CSU. Then they are split up into sub interfaces on the Serial card going to each of our remote locations...

When you total up the bandwidth on all of our subinterfaces for the Serial it works out to roughly 3Mbps. My concern though is I found on Ciscos website the documentation for a WIC-1T and the way I read it, it is telling me that the Serial interface is rated at 2Mbps. So are we not pushing more bandwidth down that Serial then it can handle? Would it not make more sense to have 1 serial interface to each T1? So 2 T1s and 2 Serial interfaces?

Maybe I am way off on this though...

Please let me know,

LR

3 REPLIES

Re: Max bandwidth WIC-1T

Hello,

So if I understand correctly you have 2T1 (equal 3 Mbps) coming into the router and a Serial interface with 2 Mbps (What is the clock rate?) transporting the traffic out of the router. Well that will allow to overload the Serial, no doubt.

The solution in your case is to apply a QoS configuration outbound on the Serial or to upgrade your outbound connection to support 3 Mbps.

For QoS have a look at "Congestion Management Overview"

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a00800b75a9.html

which will allow you to specify which type of traffic will get what amount of bandwidth from your Serial.

Hope this helps! Please rate all posts.

Regards, Martin

New Member

Re: Max bandwidth WIC-1T

Yes so what I am thinking is the problem is exactly what you said. I have 2 T1s each rated at 1.544Mbps, Then I have a serial interface that looks like this.

!

interface Serial1/0:2

description to SPrint T1

bandwidth 1500000

no ip address

encapsulation frame-relay

frame-relay traffic-shaping

frame-relay lmi-type cisco

!

interface Serial1/0:2.1 point-to-point

description to location 768k

bandwidth 768000

ip address 10.xxx.xxx.xxx 255.255.255.0

frame-relay class 768sprint

frame-relay interface-dlci 100

vofr cisco

!

interface Serial1/0:2.2 point-to-point

description to location 384k

bandwidth 384000

ip address 10.xxx.xxx.xxx 255.255.255.0

frame-relay class 384

frame-relay interface-dlci 101

vofr cisco

!

interface Serial1/0:2.3 point-to-point

description to location 512k

bandwidth 512000

ip address 10.xxx.xxx.xxx 255.255.255.0

frame-relay class 512sprint

frame-relay interface-dlci 102 IETF

!

interface Serial1/1:3

description to SPrint T1

bandwidth 1500000

no ip address

encapsulation frame-relay

load-interval 30

frame-relay traffic-shaping

frame-relay lmi-type cisco

!

interface Serial1/1:3.1 point-to-point

description to location 512k

bandwidth 512000

ip address 10.xxx.xxx.xxx 255.255.255.0

frame-relay class 512

frame-relay interface-dlci 100

vofr cisco

!

interface Serial1/1:3.2 point-to-point

description to location 128k

bandwidth 128000

ip address 10.xxx.xxx.xxx 255.255.255.0

frame-relay class 128sprint

frame-relay interface-dlci 101

vofr cisco

!

interface Serial1/1:3.3 point-to-point

description to location 512k

bandwidth 512000

ip address 10.xxx.xxx.xxx 255.255.255.0

frame-relay class 512

frame-relay interface-dlci 102

vofr cisco

!

interface Serial1/1:3.4 point-to-point

description to location 384k

bandwidth 384000

ip address 10.xxx.xxx.xxx 255.255.255.0

frame-relay class 384k

frame-relay interface-dlci 103

vofr cisco

!

So when I look at this it looks like to me that I have 1 serial interface called Serial1. Then off of that we have made a subinterfaces for each location. When you total up all of the subinterfaces bandwidth it totals out to ~3Mbps. My understanding from reading the following article: http://www.cisco.com/en/US/customer/products/hw/modules/ps3129/products_tech_note09186a00800b0859.shtml

Is that a WIC-1T is only rated to handle 2Mbps so then obviously we are pushing more traffic down the serial interface than it can handle. I am looking for a confirmation from you to say that yes this Serial card can only handle 2Mbps or no it should easily be able to handle both T1s traffic.

Please let me know what you all think, Thank you so much,

LR

New Member

Re: Max bandwidth WIC-1T

Hello LR,

could you provide also the map-classes that belong to the "frame-relay class xxx"

What are your readings of "show interface Serial1/0:2" and "show interface Serial1/1:3" durring times when problems arise? As well as the readings of "show frame-relay pvc"?

With Frame-Relay you might get away with "overbooking" an interface as long as not all your connected lokations generate larger volumes of traffic at the same time.

Regards,

Dirk.

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