Hope someone can help. I am setting up a lab with three Cisco 2500 routers.I am using DCE DTE crossover cables between the routers. On one link I am getting Serial interface up down. I have checked the keep alive settings are both interfaces are set to 10 sec and encapsulation settings are both set to HDLC. I have the clock rate configured on the DCE end (whch is where I get the up down)and I have changed the crossover cable and still no joy. Any ideas?
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Serial interface up line protocol down
- Thread starter bsludick
- Start date
- Thread starter
- #43
Hi Guys,
Tried putting the clocking on Router 3, serial 1 interface instead of Router 1 and no joy. Seeing up down on Serial 1 interface of router 3 now. I have switched the cables back to the way they were and still getting same up down on serial 1, router 1.
The routers are 2500's and are linked via dce dte serial crossover cables in a triangle with router 1 at the top.
All the other links work fine ....it is just the link between router 1 and router 3. The physicial interface must be fine as when I plug the serial cable from the serial0 interface into the Serial1 interface it comes up up!!
Any other suggestions, could it be that the 2500 routers do not like the way I setup my lab?
Thanks
Tried putting the clocking on Router 3, serial 1 interface instead of Router 1 and no joy. Seeing up down on Serial 1 interface of router 3 now. I have switched the cables back to the way they were and still getting same up down on serial 1, router 1.
The routers are 2500's and are linked via dce dte serial crossover cables in a triangle with router 1 at the top.
All the other links work fine ....it is just the link between router 1 and router 3. The physicial interface must be fine as when I plug the serial cable from the serial0 interface into the Serial1 interface it comes up up!!
Any other suggestions, could it be that the 2500 routers do not like the way I setup my lab?
Thanks
jneiberger
Technical User
It's not possible that they just don't like the setup. 
You either have a flaky cable, a flaky interface or a bad configuration. This is a very straightforward and common lab configuration. It's not complex and you seem to have it configured properly. If you see that one side is up/up, that indicates that that router is receiving layer two keepalives from the other side. However, the side that is up/down is not receiving layer two information. That is an indication that you physical have electrical connectivity on the requisite pins to get a physical "up" status, but you do not have proper connectivity on the data pins.
You either have a flaky cable, a flaky interface or a bad configuration. This is a very straightforward and common lab configuration. It's not complex and you seem to have it configured properly. If you see that one side is up/up, that indicates that that router is receiving layer two keepalives from the other side. However, the side that is up/down is not receiving layer two information. That is an indication that you physical have electrical connectivity on the requisite pins to get a physical "up" status, but you do not have proper connectivity on the data pins.- Thread starter
- #46
Apologies not getting this posted sooner but here are all there configs, I did a sh ip int brief as well on each router.
----------------------------
Router1
**********************
Router1#
Router1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.20 YES NVRAM up up
Loopback0 10.1.10.2 YES NVRAM up up
Serial0 10.1.1.2 YES NVRAM up up
Serial1 10.1.2.2 YES NVRAM up down
Router1#
Router1#
Router1#sh run
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router1
!
enable password cisco
!
ip subnet-zero
ip dhcp excluded-address 192.168.0.1 192.168.0.101
!
ip dhcp pool lab
network 192.168.0.0 255.255.255.0
default-router 192.168.0.1
dns-server 192.168.0.1
lease infinite
!
!
!
!
interface Loopback0
ip address 10.1.10.2 255.255.255.0
no ip directed-broadcast
!
interface Ethernet0
ip address 192.168.0.20 255.255.255.0
no ip directed-broadcast
!
interface Serial0
description serial link to router 2
ip address 10.1.1.2 255.255.255.0
no ip directed-broadcast
no ip mroute-cache
no fair-queue
clockrate 56000
!
interface Serial1
description Link to Router 3
ip address 10.1.2.2 255.255.255.0
no ip directed-broadcast
no fair-queue
clockrate 56000
!
interface BRI0
no ip address
no ip directed-broadcast
shutdown
!
ip classless
no ip http server
!
!
banner motd ^C Welcome to the Cisco test lab - router1 ^C
!
line con 0
password cisco
login
transport input none
line aux 0
password cisco
login
line vty 0 1
password cisco
login
line vty 2 4
login
!
end
Router1#
************************
Router 2
Router2#
Router2#sh ip int brief
Interface IP-Address OK? Method Status Prot
ocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.21 YES NVRAM up down
Loopback0 10.1.10.3 YES NVRAM up up
Serial0 10.1.1.3 YES NVRAM up up
Serial1 10.1.3.2 YES NVRAM up up
Router2#
Router2#
Router2#sh run
Building configuration...
Current configuration : 687 bytes
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router2
!
enable password cisco
!
!
!
!
!
ip subnet-zero
!
!
!
!
!
!
interface Loopback0
ip address 10.1.10.3 255.255.255.0
!
interface Ethernet0
ip address 192.168.0.21 255.255.255.0
!
interface Serial0
description serial link to router 1
ip address 10.1.1.3 255.255.255.0
no fair-queue
!
interface Serial1
description Serial Link to Router 3
ip address 10.1.3.2 255.255.255.0
clockrate 56000
!
interface BRI0
no ip address
shutdown
!
ip classless
ip http server
!
!
!
line con 0
password cisco
login
line aux 0
line vty 0 4
password cisco
login
!
end
Router2#
*********************************
Router 3
router3#
router3#sh ip int brief
Interface IP-Address OK? Method Status Protocol
Ethernet0 192.168.0.22 YES NVRAM up up
Serial0 10.1.3.3 YES NVRAM up up
Serial1 10.1.2.3 YES NVRAM up up
router3#
router3#
router3#sh run
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname router3
!
enable secret 5 $1$VtbO$CsNywhxYwKoJGQ7OT8oc2/
enable password copper01
!
ip subnet-zero
no ip routing
!
!
!
interface Ethernet0
ip address 192.168.0.22 255.255.255.0
no ip directed-broadcast
no ip route-cache
no ip mroute-cache
!
interface Serial0
description serial link to Router 2
ip address 10.1.3.3 255.255.255.0
no ip directed-broadcast
no ip route-cache
no ip mroute-cache
!
interface Serial1
description Serial link to Router 1
ip address 10.1.2.3 255.255.255.0
no ip directed-broadcast
no ip route-cache
no ip mroute-cache
!
ip classless
!
!
line con 0
logging synchronous
transport input none
line aux 0
line vty 0 4
password cisco
login
!
end
router3#
***************************************
----------------------------
Router1
**********************
Router1#
Router1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.20 YES NVRAM up up
Loopback0 10.1.10.2 YES NVRAM up up
Serial0 10.1.1.2 YES NVRAM up up
Serial1 10.1.2.2 YES NVRAM up down
Router1#
Router1#
Router1#sh run
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router1
!
enable password cisco
!
ip subnet-zero
ip dhcp excluded-address 192.168.0.1 192.168.0.101
!
ip dhcp pool lab
network 192.168.0.0 255.255.255.0
default-router 192.168.0.1
dns-server 192.168.0.1
lease infinite
!
!
!
!
interface Loopback0
ip address 10.1.10.2 255.255.255.0
no ip directed-broadcast
!
interface Ethernet0
ip address 192.168.0.20 255.255.255.0
no ip directed-broadcast
!
interface Serial0
description serial link to router 2
ip address 10.1.1.2 255.255.255.0
no ip directed-broadcast
no ip mroute-cache
no fair-queue
clockrate 56000
!
interface Serial1
description Link to Router 3
ip address 10.1.2.2 255.255.255.0
no ip directed-broadcast
no fair-queue
clockrate 56000
!
interface BRI0
no ip address
no ip directed-broadcast
shutdown
!
ip classless
no ip http server
!
!
banner motd ^C Welcome to the Cisco test lab - router1 ^C
!
line con 0
password cisco
login
transport input none
line aux 0
password cisco
login
line vty 0 1
password cisco
login
line vty 2 4
login
!
end
Router1#
************************
Router 2
Router2#
Router2#sh ip int brief
Interface IP-Address OK? Method Status Prot
ocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.21 YES NVRAM up down
Loopback0 10.1.10.3 YES NVRAM up up
Serial0 10.1.1.3 YES NVRAM up up
Serial1 10.1.3.2 YES NVRAM up up
Router2#
Router2#
Router2#sh run
Building configuration...
Current configuration : 687 bytes
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router2
!
enable password cisco
!
!
!
!
!
ip subnet-zero
!
!
!
!
!
!
interface Loopback0
ip address 10.1.10.3 255.255.255.0
!
interface Ethernet0
ip address 192.168.0.21 255.255.255.0
!
interface Serial0
description serial link to router 1
ip address 10.1.1.3 255.255.255.0
no fair-queue
!
interface Serial1
description Serial Link to Router 3
ip address 10.1.3.2 255.255.255.0
clockrate 56000
!
interface BRI0
no ip address
shutdown
!
ip classless
ip http server
!
!
!
line con 0
password cisco
login
line aux 0
line vty 0 4
password cisco
login
!
end
Router2#
*********************************
Router 3
router3#
router3#sh ip int brief
Interface IP-Address OK? Method Status Protocol
Ethernet0 192.168.0.22 YES NVRAM up up
Serial0 10.1.3.3 YES NVRAM up up
Serial1 10.1.2.3 YES NVRAM up up
router3#
router3#
router3#sh run
Building configuration...
Current configuration:
!
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname router3
!
enable secret 5 $1$VtbO$CsNywhxYwKoJGQ7OT8oc2/
enable password copper01
!
ip subnet-zero
no ip routing
!
!
!
interface Ethernet0
ip address 192.168.0.22 255.255.255.0
no ip directed-broadcast
no ip route-cache
no ip mroute-cache
!
interface Serial0
description serial link to Router 2
ip address 10.1.3.3 255.255.255.0
no ip directed-broadcast
no ip route-cache
no ip mroute-cache
!
interface Serial1
description Serial link to Router 1
ip address 10.1.2.3 255.255.255.0
no ip directed-broadcast
no ip route-cache
no ip mroute-cache
!
ip classless
!
!
line con 0
logging synchronous
transport input none
line aux 0
line vty 0 4
password cisco
login
!
end
router3#
***************************************
- Thread starter
- #47
Right away I see that the queueing does not match on R1 S1 with the queueing on R3 S1, which is the link you had trouble with in the first place. You have no WFQ on R1 S1 probably fifo), but WQF is enabled on R3 S1...that's the only thing I see from the configs.
Without having to weed through all this, tell me what you've had problems with, and what you've done. I see you tried swapping the cable, and it came up/up, but then it all gets hairy...did it stay that way?
I would take a working cable (up/up on both sides), and plug the DCE end into R3 S1, and DTE end R1 S1, make them both fifo (on R3 S1, no fair-queue), clock the DCE end (R3 S1) and tell us what happens, and for how long. Also, look at the connections on the interfaces you put the supposed "bad" cable on. Let's start over...
Burt
Without having to weed through all this, tell me what you've had problems with, and what you've done. I see you tried swapping the cable, and it came up/up, but then it all gets hairy...did it stay that way?
I would take a working cable (up/up on both sides), and plug the DCE end into R3 S1, and DTE end R1 S1, make them both fifo (on R3 S1, no fair-queue), clock the DCE end (R3 S1) and tell us what happens, and for how long. Also, look at the connections on the interfaces you put the supposed "bad" cable on. Let's start over...
Burt
- Thread starter
- #50
burtsbees,
I have disconnect the router2 so it is just Router1 and Router3 and still getting same error.
Router1#
Router1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.20 YES NVRAM up up
Loopback0 10.1.10.2 YES NVRAM up up
Serial0 10.1.1.2 YES NVRAM down down
Serial1 10.1.2.2 YES NVRAM up down
Router1#
Serial1 is up, line protocol is down
Hardware is HD64570
Description: Link to Router 3
Internet address is 10.1.2.2/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input never, output 00:00:05, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
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 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
37 packets output, 1670 bytes, 0 underruns
0 output errors, 0 collisions, 14 interface resets
0 output buffer failures, 0 output buffers swapped out
38 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
Router1#
---------
router 3
---------
router3#
router3#sh ip int brief
Interface IP-Address OK? Method Status Protocol
Ethernet0 192.168.0.22 YES NVRAM up up
Serial0 10.1.3.3 YES NVRAM down down
Serial1 10.1.2.3 YES NVRAM up up
router3#
router3#sh int serial1
Serial1 is up, line protocol is up
Hardware is HD64570
Description: Serial link to Router 1
Internet address is 10.1.2.3/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 00:00:04, output 00:00:07, 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: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/3/256 (active/max active/max total)
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
31 packets input, 1538 bytes, 0 no buffer
Received 31 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
62 packets output, 9200 bytes, 0 underruns
0 output errors, 0 collisions, 16 interface resets
0 output buffer failures, 0 output buffers swapped out
28 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
router3#
I have disconnect the router2 so it is just Router1 and Router3 and still getting same error.
Router1#
Router1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.20 YES NVRAM up up
Loopback0 10.1.10.2 YES NVRAM up up
Serial0 10.1.1.2 YES NVRAM down down
Serial1 10.1.2.2 YES NVRAM up down
Router1#
Serial1 is up, line protocol is down
Hardware is HD64570
Description: Link to Router 3
Internet address is 10.1.2.2/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
Last input never, output 00:00:05, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
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 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
37 packets output, 1670 bytes, 0 underruns
0 output errors, 0 collisions, 14 interface resets
0 output buffer failures, 0 output buffers swapped out
38 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
Router1#
---------
router 3
---------
router3#
router3#sh ip int brief
Interface IP-Address OK? Method Status Protocol
Ethernet0 192.168.0.22 YES NVRAM up up
Serial0 10.1.3.3 YES NVRAM down down
Serial1 10.1.2.3 YES NVRAM up up
router3#
router3#sh int serial1
Serial1 is up, line protocol is up
Hardware is HD64570
Description: Serial link to Router 1
Internet address is 10.1.2.3/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation HDLC, loopback not set, keepalive set (10 sec)
Last input 00:00:04, output 00:00:07, 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: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/3/256 (active/max active/max total)
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
31 packets input, 1538 bytes, 0 no buffer
Received 31 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
62 packets output, 9200 bytes, 0 underruns
0 output errors, 0 collisions, 16 interface resets
0 output buffer failures, 0 output buffers swapped out
28 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=up
router3#
jneiberger
Technical User
I will say it again: this is a physical problem! You either have bad cables or you have a bad interface. You can see that one interface has bidirectional traffic but the other interface is not receiving any traffic. That's a sure sign of a bad cable or a bad interface.
- Thread starter
- #52
jneiberger,
Been down this road before...
I have switch router2 back on and plugged router2's cable into the 'bad interface' and the interface comes!
Router1#
Router1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.20 YES NVRAM up up
Loopback0 10.1.10.2 YES NVRAM up up
Serial0 10.1.1.2 YES NVRAM down down
Serial1 10.1.2.2 YES NVRAM up up
Router1#
So it cannot be the interface then can it?
I know the link between router 1 and router 2 is working so taken the cable from there and the results below....still up down!
Router1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.20 YES NVRAM up up
Loopback0 10.1.10.2 YES NVRAM up up
Serial0 10.1.1.2 YES NVRAM down down
Serial1 10.1.2.2 YES NVRAM up down
So I am fairly confident it is not the cable either....
anythingelse I need to check.
Been down this road before...
I have switch router2 back on and plugged router2's cable into the 'bad interface' and the interface comes!
Router1#
Router1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.20 YES NVRAM up up
Loopback0 10.1.10.2 YES NVRAM up up
Serial0 10.1.1.2 YES NVRAM down down
Serial1 10.1.2.2 YES NVRAM up up
Router1#
So it cannot be the interface then can it?
I know the link between router 1 and router 2 is working so taken the cable from there and the results below....still up down!
Router1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES NVRAM administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 192.168.0.20 YES NVRAM up up
Loopback0 10.1.10.2 YES NVRAM up up
Serial0 10.1.1.2 YES NVRAM down down
Serial1 10.1.2.2 YES NVRAM up down
So I am fairly confident it is not the cable either....
anythingelse I need to check.
jneiberger
Technical User
So, r2 comes up with no problem when connected to the problematic interfaces on r1 or r3? Using the same cables?
- Thread starter
- #54
Hi Burtsbees
The only difference between the Router1 and Router3 configs was the queueing:
Router3
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Router1
Last clearing of "show interface" counters 01:43:32
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
This wouldn't have anything to do with the up down situation at the moment?
The only difference between the Router1 and Router3 configs was the queueing:
Router3
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Router1
Last clearing of "show interface" counters 01:43:32
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
This wouldn't have anything to do with the up down situation at the moment?
jneiberger
Technical User
Queueing will have no bearing on the status of your layer two connection. The problem, as seen in the output you posted, is that when r1 and r3 are connected, r1 sees no layer two frames whatsoever, even though r3 is sending them. That is not a configuration issue. If r1 is not seeing the layer two keepalives from r3, it will leave the status as up/down. It will not bring the layer two status to UP unless it starts seeing valid keepalives.
I have switch router2 back on and plugged router2's cable into the 'bad interface' and the interface comes!"
Good cable...
"I know the link between router 1 and router 2 is working so taken the cable from there and the results below....still up down!"
Bad cable.
Burt
Good cable...
"I know the link between router 1 and router 2 is working so taken the cable from there and the results below....still up down!"
Bad cable.
Burt
- Thread starter
- #57
jneiberger
Technical User
You can see from the "show interface" output that keepalives are sent every 10 seconds. You could turn on serial interface debugging if you feel like it, but it's really not necessary. R1 isn't receiving any frames at all from R3, so there's no point in turning on debugging. There's nothing to debug.
This is almost certainly a physical problem somewhere. Just for grins, have you tried changing the layer two protocol? Set both sides to frame relay or PPP and see if the behavior changes. It shouldn't make a difference, but it's something you can try if you feel sure that your cables and interfaces are good.
This is almost certainly a physical problem somewhere. Just for grins, have you tried changing the layer two protocol? Set both sides to frame relay or PPP and see if the behavior changes. It shouldn't make a difference, but it's something you can try if you feel sure that your cables and interfaces are good.
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