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New Member

Point to Point T1 problem

I have a T1 connection between two locations. Some while ago we started having latency issues with the lines.  when I run a ping from the router to the other routher this is the result I get.

Success rate is 100 percent (5/5), round-trip min/avg/max = 8/8/8 ms
SCFU01#ping 192.168.2.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.2, timeout is 2 seconds:
!!...
Success rate is 40 percent (2/5), round-trip min/avg/max = 8/8/8 ms
SCFU01#ping 192.168.2.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.2, timeout is 2 seconds:
..!!!
Success rate is 60 percent (3/5), round-trip min/avg/max = 8/8/8 ms
SCFU01#ping 192.168.2.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/4 ms

The telco company is telling me that the line was tested for over one hour on several occasions and it is clean, but it was working before fine and I did not change anything on the routers. I replaced the Wic t1 cards in both routers and get the same issue. Below are the router configs.

Router 1

memory-size iomem 25
tdm clock T1 0/0 both export line
tdm clock T1 0/1 both import T1 0/0 internal
voice-card 0
!
ip subnet-zero
!
!
!
!
!
!
!
!
!
!
!
!
no voice hpi capture buffer
no voice hpi capture destination
!
!
!
!
controller T1 0/0
framing esf
linecode b8zs
channel-group 0 timeslots 1-24
no yellow generation
no yellow detection
!
controller T1 0/1
framing esf
linecode b8zs
no yellow generation
no yellow detection
!
!
interface FastEthernet0/0
ip address 192.168.1.30 255.255.255.0
speed auto
!
interface Serial0/0:0
ip address 172.16.254.1 255.255.255.192
encapsulation ppp
!
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.1.32
ip route 192.168.2.0 255.255.255.0 Serial0/0:0
ip route 192.168.3.0 255.255.255.0 Serial0/0:0
no ip http server
!
!
!
!
call rsvp-sync
!
dial-peer cor custom
!
!
!
!
line con 0
login local
transport output pad udptn telnet rlogin
line aux 0
line vty 0 4
login local
transport input telnet
line vty 5 15
login local
transport input telnet
!
end

Router 2

memory-size iomem 25
clock timezone EST -5
clock summer-time EDT recurring
tdm clock T1 0/0 both export line
tdm clock T1 0/1 both import T1 0/0 internal
voice-card 0
!
ip subnet-zero
!
!
!
!
!
!
!
!
!
!
!
!
no voice hpi capture buffer
no voice hpi capture destination
!
!
!
!
controller T1 0/0
framing esf
linecode b8zs
channel-group 0 timeslots 1-24
no yellow generation
no yellow detection
!
controller T1 0/1
framing esf
linecode b8zs
no yellow generation
no yellow detection
!
!
interface FastEthernet0/0
description Data
ip address 192.168.2.2 255.255.255.0
speed auto
!
interface Serial0/0:0
description point-to-point to Elmsford
ip address 172.16.254.2 255.255.255.192
encapsulation ppp
!
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.2.1
ip route 192.168.1.0 255.255.255.0 Serial0/0:0
ip route 192.168.3.0 255.255.255.0 192.168.2.1
no ip http server
!
!
!
!
call rsvp-sync
!
dial-peer cor custom
!
!
!
!
line con 0
login local
transport output pad udptn telnet rlogin
line aux 0
session-timeout 10
login local
modem InOut
modem autoconfigure type mt56k
transport input all
transport output pad udptn telnet rlogin
autohangup
stopbits 1
speed 2400
flowcontrol hardware
line vty 0 4
login local
transport input telnet
line vty 5 15
login local
transport input telnet
!
end

Any help would be really appreciated as I cant figure what the problem is.

Thanks.

8 REPLIES
New Member

Re: Point to Point T1 problem

You need to make sure that when you have your TELCO provider do the testing that you schedule

"intrusive" testing for when you don't need the circuit. This will allow them to do more elaborate testing but will cause an outage on the circuit. You may need to have them show up on-site at each end and perform BERT (Bit Error Rate Testing) on the circuit.

New Member

Re: Point to Point T1 problem

All of the above mentioned was done. They tested it several times. I still believe it is a problem with the circuit, but they will not acknowledge that in fact it is the circuit.

Silver

Re: Point to Point T1 problem

What is your interface utilization during times of poor performance?  Are you seeing errors on the interfaces or controllers?  If so what are the errors?

Sometimes point to point T1's require the customer to supply clock on one side.  Have you had a clocking conversation with the service provider?


Chris

New Member

Re: Point to Point T1 problem

This is what I have

Serial0/0:0 is up, line protocol is up
  Hardware is DSX1
  Internet address is 172.16.254.1/26
  MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec,
     reliability 162/255, txload 1/255, rxload 1/255
  Encapsulation PPP, LCP Open
  Open: CDPCP, IPCP, loopback not set
  Last input 00:00:23, output 00:00:13, output hang never
  Last clearing of "show interface" counters 00:12:58
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: weighted fair
  Output queue: 0/1000/64/0 (size/max total/threshold/drops)
     Conversations  0/2/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 1152 kilobits/sec
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     996 packets input, 365979 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
    401880 input errors, 42834 CRC, 358138 frame, 0 overrun, 0 ignored, 908 abo
rt
     722 packets output, 99160 bytes, 0 underruns
     0 output errors, 0 collisions, 8 interface resets
     0 output buffer failures, 0 output buffers swapped out
     11 carrier transitions
  Timeslot(s) Used:1-24, SCC: 0, Transmitter delay is 0 flags

I have clocking set on routers.

tdm clock T1 0/0 both export line
tdm clock T1 0/1 both import T1 0/0 internal

Silver

Re: Point to Point T1 problem

  Last clearing of "show interface" counters 00:12:58
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: weighted fair
  Output queue: 0/1000/64/0 (size/max total/threshold/drops)
     Conversations  0/2/256 (active/max active/max total)
     Reserved Conversations 0/0 (allocated/max allocated)
     Available Bandwidth 1152 kilobits/sec
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     996 packets input, 365979 bytes, 0 no buffer
     Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
    401880 input errors, 42834 CRC, 358138 frame, 0 overrun, 0 ignored, 908 abo
rt

     722 packets output, 99160 bytes, 0 underruns
     0 output errors, 0 collisions, 8 interface resets
     0 output buffer failures, 0 output buffers swapped out
     11 carrier transitions
  Timeslot(s) Used:1-24, SCC: 0, Transmitter delay is 0 flags


#################


After 13 minutes there are over 400 thousand input errors.  Certainly looks like a circuit issue.


Both routers are configured to pull clock off the line.  Ask the service provider if they are providing clock.  If they are not at least on of your routers will need to be changed to provide clock.


From the folloiwng link: http://www.cisco.com/en/US/products/hw/routers/ps259/products_tech_note09186a008031a072.shtml

For 1751V and 1760

These devices use different commands and terminology for their       clocking. In the voice mode of operation, the clocking can be exported (the       clock is taken externally from the line or interface), or imported (the clock       on a port can be taken from the internal oscillator of the router, or another       port or interface).

tdm clock {T1 | E1} slot/port {voice | data | both} export line

!--- Issue this command on one line:

tdm clock {T1 | E1} slot/port {voice | data | both} import          {T1 | E1 | atm | bri | onboard} slot/port {line | internal}

This import and export terminology can be confusing, because the term       import seems to suggest that the clocking comes directly from the referenced       port or interface, and not from the internal oscillator of the router.

Refer to       Clock      Configuration for Cisco 1751/1760 Routers for more information.

New Member

Re: Point to Point T1 problem

Your CRC's are indicative of a physical problem. You need to replace the cables on your rout

ers and if this doesn't clear the problem up then you need to call your service provider back and have them get out there and do

BERT testing on each end.

New Member

Re: Point to Point T1 problem

Echo Jason Bliss on changing the cables b/c of the CRC errors.  I go through this ALL the time w/ my provider.

New Member

Re: Point to Point T1 problem

Thank you for all your help guys. It was actually the clocking on the routers. I did not realize, nor was I informed that at one point we were provided with clocking and then all the sudden they stoped. Verizon did not inform me of the changes so I figured clocking was correct.  I changed it on one of the routers to tdm clock T1 0/0 both import onboard internal and now it works like a charm Thanks again for all your help.

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