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New Member

Serial interface problem

Hi,

I have some MWR1941-DC router. This router has come up a redundancy( mode y cable configuration). As per management order I confifure this router for WAN link for data connectivity. I don't know how to remove configuration of redundancey . I have connected four WAN with this router . Now one of the serial interface's line protocol is going UP and down. I can not fix the problem. I am sending you the sh run, sh interface and sh contr e1 command's output. Pls tell me what should I do. Note that its a production router.

.....bikash

10 REPLIES
Gold

Re: Serial interface problem

The multilink configuration looks strange but that is not your issue with 0/2

You are getting many errors on this line. It is very likely the telco has a issue. You need to call them and have them check the line.

9866 Line Code Violations, 1835 Path Code Violations

This indicates the circuit is having problems at a very low level. Even thought he circuit is up/down this is a problem in the tail circuit. It must just not be getting enough errors to go down/down but I suspect it does go down/down for short periods of time.

New Member

Re: Serial interface problem

Hi,

You are right that the link going up/down for short period. More advise/suggestion/info is eagerly required.

Biaksh

Silver

Re: Serial interface problem

Hi ,

Most of the times it is a problem with telco.To isolate whether it is a telco problem or router probelm , you can do loopback test in the router.

The below link gives info about loopback test..

http://www.cisco.com/warp/customer/471/hard_loopback.html

Follow-up with telco and take necessary tests with telco.

Thanks,

satish

New Member

Re: Serial interface problem

Hi satish;can u list a link without a CCO

10XS

Silver

Re: Serial interface problem

Hi ,

Procedure for hard loopback test.

If you want to check that your hardware works ok or not, you can perform a hardware

loopback test. Here are the instructions for conducting a HARD loopback test for a CSU/DSU

connected to a Cisco Systems Router.

Step 1: Create T1/E1 loopback plug

- Take a working straight through RJ-45 cable (as short as possible)

- Using wire cutters, cut the cable so there's about 5" of cable and the

RJ-45 head

- The pins on an RJ-45 cable plug are numbered from 1 through 8. With the

metal pins of the plug facing toward you, pin 1 is the leftmost pin.

- Take the exposed wires corresponding to pins 1 & 4 strip them, then twist

them together

- Do the same for pins 2 & 5

- Leave the rest of the wires alone

Step 2: Install the loopback plug

- Remove the T1/E1 (RJ-45) Connector from the Network port of the CSU/DSU

- Plug the loopback plug into the same port you just removed T1/E1 cable from

Step 3: Save your router configuration

- Enter enable mode: enable

- Use the cmd: write mem

Step 4: Set the encapsulation to HDLC (Cisco Routers will only PROPERLY loop

in HDLC)

- Enter config terminal mode: config term

- Enter the interface config mode: interface serial [your T1/E1 interface #]

- Issue the cmd: encap HDLC

- Clock source should be internal

- Exit config terminal mode: Ctrl + Z

Step 5: Set an IP Address (ONLY IF YOU DON'T HAVE AN IP ON THE MAIN

INTERFACE ALREADY)

- Issue the cmd: sh run

- Is there an IP address under your T1/E1's MAIN (physical) interface?

- If YES, then skip to STEP 6

- If NO, then continue with STEP 5

- Enter config terminal mode: config term

- Enter the interface config mode: interface serial [your T1/E1 interface #]

- Issue the cmd: ip address 10.13.13.13 255.255.255.0

* MAKE SURE THIS ADDRESS DOESN'T OVERLAP WITH ANY OF YOUR OTHER NETWORKS

- If it overlaps, use any other free address & a netmask of 255.255.255.0

- Exit config terminal mode: Ctrl + Z

Step 6: Clear Counters

- Type: clear counters

- Press ENTER a couple of times

Step 7: Perform Extended Pings

- Type: ping ip

- Target address = IP of the local T1/E1 int. (the int. you just configured

HDLC on)

- Repeat count = 50

- Datagram size = 1500

- Timeout = press ENTER

- Extended cmds = yes

- Source Address = press ENTER

- Type of service = press ENTER

- Set Df bit in ip header = press ENTER

- Validate reply data = press ENTER

- Data pattern: 0x0000 (all zeros)

- Press ENTER 3 times

Step 8: Perform additional extended pings with different data patters

- Repeat step 7, but use a DATA PATTERN of 0x1111

- Repeat step 7, but use a DATA PATTERN of 0xffff

- Repeat step 7, but use a DATA PATTERN of 0xaaaa

Step 9: Verify results

- All of the above pings should have been 100% successful

- Type: show interface serial [your T1/E1 interface #]

- Your T1/E1 serial interface should have no crc, frame, input, etc. errors

* 5th & 6th lines from the bottom of the show interface cmd output

* If all pings are 100% successful and there are no errors, then your router

should be good, and this is either a

cabling or telco issue.

Step 10: Return router to original state

- Remove loopback plug from the CSU/DSU and replace the T1/E1 cable back in

network port

- On the router, type: copy start run

I couldn't able to attach a link without CCO.

Hope it helps you.

Thanks,

satish

New Member

Re: Serial interface problem

10XS SATISH

New Member

Re: Serial interface problem

Thankx a lot

New Member

Re: Serial interface problem

Dear Satish,

I do not have CCO password. But One thing I did. I made a loopback cable ( 1-4 & 2-5 cable short) and did the test. I found serial is up, line protocol is down , at the hardware loopback test. It is taken to aback that after failing that test ,the link is still going up and down now and then.

Bikash...

Silver

Re: Serial interface problem

Hi Bikash ,

Have you followed the steps mentioned above properly. When you are doing hard loopback test both serial and line protocol should be up and you should not see any errors on serial interface.

Can you do the test once againg.I will try to give the link wothout cco login.

After doing test please let me know the result and please paste sh controller and sh interface at the time of test.

Thanks,

satish

Silver

Re: Serial interface problem

Hi ,

Please check the below link for hard loop back test.

http://www.cisco.com/en/US/tech/tk713/tk628/technologies_tech_note09186a00800a754b.shtml

It shouldn't ask CCO password.

Below link is for trouble shooting tips.

http://www.cisco.com/en/US/tech/tk713/tk628/tsd_technology_support_troubleshooting_technotes_list.html

Hope it helps you.

Thanks,

satish

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