Connecting two 2620 router via T1 CSU/DSU via crossover cable

[punnoosej]

Hi-

I have two 2620 router with T1 CSU/DSU. I am trying to connect both router via a crossover cable. The pins outs are 1->4, and 2->5.

On both routers I am seeing alarm & s0/0 is down/down. On one of the routers I am seeing CD light. I am I missing something or is it bad crossover cable.

[scarothe]

Greetings:

You did not say what protocol you are running. Assuming your cable is good, set one of the CSU's for internal clocking. If you are doing a F-Relay setup, make sure that the serial interfaces are set to keepalive=0 and set your F-Relay map statements to point to the same DLCI on both sides.

If you have done these things, then you will want to verify the cable.

Thanks...Steve

[jkim]

Pin out are 1->5 and 2->4. Try that and it should work.

John

[bhedlund]

Actually, 1 -> 4 2 -> 5 is the correct pinout

for T1 Xover.

If the int is down/down remake your cable and post your configs for the ints.

Regards,

Brad

[svermill]

T-1 is bipolar, which renders the debate somewhat academic. It is merely the magnitude of the delta (or lack thereof) between the two balanced leads that conveys information. You can never truley invert a T-1.

[jkim]

I've always used 1->5, and 2->4 pin outs and worked for me. Also, make sure one of the router is providing clock.

[ynverma]

ya . chk for the clock setting and also if possible tell what alarm you are getting?

[tim-griffin]

Pins 1-4 and 2-5 or 1-5 and 2-4 will both work the same. You need to make sure that one of the routers is supplying clock for the T-1

[mrepko]

ok - I'm trying the same with two 1602's & frame relay. We named one A and one B - s0 down/down on both routers. Integrated csu alarm light on for both of em. here are the configs and output from show int s0. :

lab a router - show run command:

show run

Building configuration...

Current configuration:

!

version 11.1

service udp-small-servers

service tcp-small-servers

!

hostname lab1602

!

enable secret 5 $1$7FrH$FDLHIzGZMz9A13c27i9yz1

enable password xxxxxx

!

isdn switch-type basic-5ess

!

interface Ethernet0

ip address 10.2.1.2 255.255.255.0 secondary

ip address 10.1.1.1 255.255.255.0

!

interface Serial0

description Circuit ID

no ip address

encapsulation frame-relay

no keepalive

service-module 56k clock source line

service-module 56k network-type dds

!

interface Serial0.1 point-to-point

ip address 10.1.3.1 255.255.255.0

no arp frame-relay

frame-relay interface-dlci 101

!

interface Serial0.2 point-to-point

ip address 10.1.4.1 255.255.255.0

no arp frame-relay

!

interface BRI0

ip address 10.1.2.1 255.255.255.0

!

router rip

network 10.0.0.0

!

router igrp 1

network 10.0.0.0

!

no ip classless

logging buffered

snmp-server community xxxxxx RO

!

line con 0

line vty 0 4

password ccnp

login

!

end

lab a show int s0 command:

lab1602#show int s0

Serial0 is down, line protocol is down

Hardware is QUICC Serial (with onboard CSU/DSU)

Description: Circuit ID

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255

Encapsulation FRAME-RELAY, loopback not set, keepalive not set

Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0 (size/max/drops); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/64/0 (size/threshold/drops)

Conversations 0/0 (active/max active)

Reserved Conversations 0/0 (allocated/max allocated)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 packets output, 0 bytes, 0 underruns

0 output errors, 0 collisions, 207 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=down DSR=down DTR=up RTS=up CTS=up

ok, now 1602b config:

show run

Building configuration...

Current configuration:

!

version 11.1

service udp-small-servers

service tcp-small-servers

!

hostname Router

!

enable secret 5 $1$KDz5$.srEYWfIDmYTP4/qztJ35.

enable password xxxxxx

!

isdn switch-type ntt

!

interface Ethernet0

ip address 10.2.1.1 255.255.255.0

shutdown

!

interface Serial0

no ip address

encapsulation frame-relay

no keepalive

service-module 56k clock source internal

service-module 56k network-type dds

!

interface Serial0.1 point-to-point

ip address 10.1.3.200 255.255.255.0

frame-relay interface-dlci 101

!

interface BRI0

no ip address

shutdown

!

no ip classless

logging buffered

!

line con 0

line vty 0 4

password xxxxxx

login

!

end

and 1602 b show int s0 command:

show int s0

Serial0 is down, line protocol is down

Hardware is QUICC Serial (with onboard CSU/DSU)

MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255

Encapsulation FRAME-RELAY, loopback not set, keepalive not set

Broadcast queue 0/64, broadcasts sent/dropped 0/0, interface broadcasts 0

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0 (size/max/drops); Total output drops: 0

Queueing strategy: weighted fair

Output queue: 0/64/0 (size/threshold/drops)

Conversations 0/0 (active/max active)

Reserved Conversations 0/0 (allocated/max allocated)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 packets output, 0 bytes, 0 underruns

0 output errors, 0 collisions, 79 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=down DSR=down DTR=up RTS=up CTS=up

Any help would be appreciated. I tried the regular cat 5 cables supplied with the routers, what we call regular crossover cables, and had a friend lend me T-1 crossover cables. same results with all cables.

the only thing that sticks out to me is DCD=down and DSR=down in all cases.

thanks for any insight :)

[tim-griffin]

Are these connected to each othe rwith a cross-over cable? With a 56k you would cross pins 1-7 and 2-8. Also, both are set up as frame relay end devices (DTE) and won't work that way with a cross-over cable. One has to be set up as a frame relay switch (DCE).