Does it matter if you use different Cisco IOS's on a Serial

Hi, first post, so please be gentle. I've just been practicing setting up a little network, but for some reason I cant get a serial connection between a Cisco 2500 running IOS 12.3 and a Cisco 2600 running IOS 12.4.

I've got a second serial link off the Cisco 2500 (IOS 12.3) to a second Cisco 2500 also running IOS 12.3, and that runs no problem.

My question is this: could it be the different versions of IOS causing this? I've checked and rechecked the IP address, subnet, clockrate, made sure I've done the no shutdown command, but that serial link just won't come up.

Any thoughts, Oh Wise Ones?

Find more posts tagged with

Free for TechExams community: Cybersecurity salary guide

Compare cert salaries and plan your next career move

Button

Comments

shednik

Different IOS versions should not make a difference, why don't you post the running config for each interface, and a show int s x/x. What part isn't coming up?

conundrum

Sleepy is the Cisco 2600 running IOS 12.4
There's a connection to Sneezey (Cisco 2500 running IOS 12.3) on Serial 0/0

Sleepy#show ip int brief
Interface IP-Address OK? Method Status Prot
ocol
Ethernet0/0 192.168.3.1 YES NVRAM up up

Serial0/0 192.168.1.2 YES NVRAM down down

Sleepy#

Sleepy#show run
Building configuration...

Current configuration : 918 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Sleepy
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$.NAP$xt8Ke7BfI5lpgbGtFNLfa.
!
no aaa new-model
!
resource policy
!
ip subnet-zero
ip cef
!
!
no ip dhcp use vrf connected
!
!
no ip ips deny-action ips-interface
no ip domain lookup
!
!
!
!
!
!
!
!
!
interface Ethernet0/0
description This is the ethernet link to router Dopey
ip address 192.168.3.1 255.255.255.0
half-duplex
!
interface Serial0/0
description This is the serial link to Sneezey
ip address 192.168.1.2 255.255.255.0
no fair-queue
!
router rip
network 192.168.1.0
network 192.168.3.0
!
ip classless
!
ip http server
no ip http secure-server
!
!
!
control-plane
!
!
!
banner motd ^CThis is router 2600 Sleepy^C
!
line con 0
password boot
login
line aux 0
line vty 0 4
password boot
login
!
!
end

Sleepy#

Sneezey is the Cisco 2500 running IOS 12.3. The link back to Sleepy is on Serial 1.

Sneezey#show 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 192.168.4.1 YES NVRAM up up

Serial0 192.168.2.1 YES NVRAM up up

Serial1 192.168.1.1 YES NVRAM up down

Sneezey#

Sneezey#show run
Building configuration...

Current configuration : 864 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Sneezey
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$uMdo$SPheb2Z/A.mHC.aBZGEul.
!
no aaa new-model
ip subnet-zero
no ip domain lookup
!
!
!
!
interface Ethernet0
ip address 192.168.4.1 255.255.255.0
!
interface Serial0
ip address 192.168.2.1 255.255.255.0
clock rate 56000
no fair-queue
!
interface Serial1
description This is the serial link to Sleepy
ip address 192.168.1.1 255.255.255.0
!
interface BRI0
no ip address
encapsulation hdlc
shutdown
!
router rip
network 192.168.1.0
network 192.168.2.0
network 192.168.4.0
!
ip http server
ip classless
!
!
!
banner motd ^CThis is router 2500 Sneezey^C
!
line con 0
exec-timeout 0 0
password boot
login
line aux 0
line vty 0 4
password boot
login
!
end

Sneezey#

Hope you can cast some light on this. I hope I'm just doing something stupid and easily fixed.

Steve

Mrock4

Edit..nevermind I missed that.

dynamik

You don't have a clock rate configured.

Is that why one would show up as "up down" and the other is "down down" (I'm still learning this myself)?

Mrock4

He has a clock rate configured on the second router..if I'm looking at the right interface.

Edit #2..yea..looked at the wrong interface. You do need a clock rate on one of those ends.

conundrum

Thanks for the replies.
Checked for clockrate, it's definitely there, 56000 on both ends.
Tried putting encapsulation ppp on both ends, no difference.

i'm beginning to think that the serial interface on the Cisco 2600 (Sleepy) is duff. it's showing Down Down. I've only received my networking gear today via Ebay, this is my first go at getting it going. i'm going to see if I can scrounge another router with a serial interface from work and try that.

It's not the cable....I swapped it with another one that was working elsewhere and it made no difference.

Unless anyone has any other ideas.....

Steve

shednik

conundrum wrote:

Thanks for the replies.
Checked for clockrate, it's definitely there, 56000 on both ends.
Tried putting encapsulation ppp on both ends, no difference.

i'm beginning to think that the serial interface on the Cisco 2600 (Sleepy) is duff. it's showing Down Down. I've only received my networking gear today via Ebay, this is my first go at getting it going. i'm going to see if I can scrounge another router with a serial interface from work and try that.

It's not the cable....I swapped it with another one that was working elsewhere and it made no difference.

Unless anyone has any other ideas.....

Steve

You need to set the clock rate on the DCE end only not on both ends. The DTE end gets its clocking from the DCE.

dynamik

Did you add the clock rate since you posted those configs? You don't have it in either of those.

Do a show controller serial<num> to find out which one's the DCE.

conundrum

Yes I checked to see which end was DCE and applied a clockrate of 56000 - it made no difference.

Got a new plan. I've got another Cisco 2500 router called Grumpy (IoS 12.3) which has two serial ports, I'm going to try connecting one of those to Sleepy, see if it comes up. If it doesn't, then I'll take it that Sleepy's single serial port is U/S and see if I can get it returned to the Ebay firm which sold it me. I've only had the kit 3 days and so far that router serial port has never been up.

Steve

tech-airman

conundrum,

conundrum wrote:

Hi, first post, so please be gentle. I've just been practicing setting up a little network, but for some reason I cant get a serial connection between a Cisco 2500 running IOS 12.3 and a Cisco 2600 running IOS 12.4.

What exact model number is the "Cisco 2600" router?

conundrum wrote:

I've got a second serial link off the Cisco 2500 (IOS 12.3) to a second Cisco 2500 also running IOS 12.3, and that runs no problem.

My question is this: could it be the different versions of IOS causing this? I've checked and rechecked the IP address, subnet, clockrate, made sure I've done the no shutdown command, but that serial link just won't come up.

Any thoughts, Oh Wise Ones?

conundrum

I'm at work at the moment, so the gear isn't in front of me...

but this is the ebay link for what I bought

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=110311420609

Steve

mattrgee

Only set the clockrate on the DCE end of the serial cable. You are using a DCE-to-DTE serial cable right? Remove the clock rate from the DTE end. Not sure if you have edited the original config, but its always better to leave them as they were and post an updated one so we can see the changes.

Netwurk

Here's some things you may want to try.

Do a show controllers serial on both ends of the link to determine which side is DTE and which side is DCE.

Do a show run interface serial xx on the involved links to make sure the clock is set on the correct interface. There should be only one clock setting and it must be on the DCE side.

Hardware wise, you may want to reseat and tighten the screws on the serial card (for the 2600). You might have to power down first to do this, I forget to be honest.

cmccul002

Doesn't the Serial's need encapsulation set?

-edit- I see it on the second one, doesnt it need to be set on both?

billyr

Assuming that you have the DCE end of the cable attached to the router providing the clocking.
Ensure you have the cable head the right way round.
Although they are D shaped connectors they actually fit both ways round.

The show controllers command should tell you if this is the case. Normally it comes up with something like no cable detected on one of the ends.

dynamik

cmccul002 wrote:

Doesn't the Serial's need encapsulation set?

Don't they use HDLC by default? I don't think you need to change anything unless there's a mismatch or you want to use PPP.

shednik

dynamik wrote:

cmccul002 wrote:

Doesn't the Serial's need encapsulation set?

Don't they use HDLC by default? I don't think you need to change anything unless there's a mismatch or you want to use PPP.

Yes by default they will use HDLC

conundrum

Hi there, thanks to everyone who has replied on this.....here is the latest config file, hot off the press 5 minutes ago...... that link still doesn't work

Router 2600 Sleepy is connected via Serial 0/0 to Router 2500 Sneezey on Serial 1.
This link doesn’t work, and has never worked.
Sleepy is showing Down Down on the link, while Sneezey is showing Up Down.
The link light on the removable serial module on Sleepy is not on, and has never lit up.

I think the serial module on the Router 2600 is faulty.

I’m certain the serial cable is the right way up, and I’ve tried swapping with another cable. No change.

I'm certain I've got a clockrate set on the DCE end.

I’ve tried connecting the serial 0/0 on Sleepy to a completely different router, it still gave me Down Down.

On connecting Serial 1 on Sneezey to another router the link came up.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is router 2600 Sleepy

User Access Verification

Password:
Sleepy>en
Password:
Sleepy#show ip interface brief
Interface IP-Address OK? Method Status Prot
ocol
Ethernet0/0 192.168.3.1 YES NVRAM up up

Serial0/0 192.168.1.2 YES NVRAM down down

Sleepy#show run
Building configuration...

Current configuration : 937 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Sleepy
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$.NAP$xt8Ke7BfI5lpgbGtFNLfa.
!
no aaa new-model
!
resource policy
!
ip subnet-zero
ip cef
!
!
no ip dhcp use vrf connected
!
!
no ip ips deny-action ips-interface
no ip domain lookup
!
!
!
!
!
!
!
!
!
interface Ethernet0/0
description This is the ethernet link to router Dopey
ip address 192.168.3.1 255.255.255.0
half-duplex
!
interface Serial0/0
description This is the serial link to Sneezey
ip address 192.168.1.2 255.255.255.0
encapsulation ppp
no fair-queue
!
router rip
network 192.168.1.0
network 192.168.3.0
!
ip classless
!
ip http server
no ip http secure-server
!
!
!
control-plane
!
!
!
banner motd ^CThis is router 2600 Sleepy^C
!
line con 0
password boot
login
line aux 0
line vty 0 4
password boot
login
!
!
end

Sleepy#

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is router 2500 Sneezey

User Access Verification

Password:
Sneezey>en
Password:
Sneezey#show ip interface 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 192.168.4.1 YES NVRAM up up

Serial0 192.168.2.1 YES NVRAM up up

Serial1 192.168.1.1 YES NVRAM up down

Sneezey#show run
Building configuration...

Current configuration : 931 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Sneezey
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$uMdo$SPheb2Z/A.mHC.aBZGEul.
!
no aaa new-model
ip subnet-zero
no ip domain lookup
!
!
!
!
interface Ethernet0
ip address 192.168.4.1 255.255.255.0
!
interface Serial0
description This is the serial 0 link to Grumpy
ip address 192.168.2.1 255.255.255.0
clock rate 56000
no fair-queue
!
interface Serial1
description This is the serial link to Sleepy
ip address 192.168.1.1 255.255.255.0
clock rate 56000
!
interface BRI0
no ip address
encapsulation hdlc
shutdown
!
router rip
network 192.168.1.0
network 192.168.2.0
network 192.168.4.0
!
ip http server
ip classless
!
!
!
banner motd ^CThis is router 2500 Sneezey^C
!
line con 0
exec-timeout 0 0
password boot
login
line aux 0
line vty 0 4
password boot
login
!
end

Sneezey#

Mrock4

"Sleepy"
interface Serial0/0
description This is the serial link to Sneezey
ip address 192.168.1.2 255.255.255.0
encapsulation ppp
no fair-queue 


"Sneezey"
interface Serial1
description This is the serial link to Sleepy
ip address 192.168.1.1 255.255.255.0
clock rate 56000

If you're going to use PPP, you need to put it on both ends. Just some FYI.

Netwurk

Nothing really looks wrong in your config (but make sure the encaps match)

Try this command on the 2600 and let us know what you get

show controllers serial 0/0 | include No

If you see the line

No serial cable attached

and you do have your cable attached, then it may be a bad unit. Try unseating/reseating the card.

malcybood

I would say disable PPP on both sides first, everything else looks ok.

After you get the interfaces up in the most basic form, then try messing about with PPP

dynamik

Why is that one interface showing as "down down"? Doesn't that indicate a physical problem? Have you tried a different cable?

Mrock4

malcybood wrote:

I would say disable PPP on both sides first, everything else looks ok.

After you get the interfaces up in the most basic form, then try messing about with PPP

Whether not PPP/HDLC is configured properly, it should still show UP/DOWN at least.

tech-airman

conundrum wrote:

I'm at work at the moment, so the gear isn't in front of me...

but this is the ebay link for what I bought

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=110311420609

Steve

conundrum,

Since the auction is over, the only details available is the auction title. Once again I ask, What exact model number is the "Cisco 2600" router?

dtlokee

on sleepy serial 0/0 issue the command "encap hdlc"

Also check that you did not jam the serial connector on upside down.

conundrum

The router with the problem is a Cisco 2610. It's got a single Fastethernet port, and a plug in Serial module. The ethernet port is up with a link elsewhere, the serial is dead as a doornail.

On talking to my equipment supllier they're going to post out a new plug in serial module, hopefully that'll sort it. I live in hope.

GT-Rob

Not sure if you have tried, but the cable between the 2 2500s works for sure, so swap that with the one between the 2500 and 2600. This will tell you if its the cable or sure.

Otherwise, I would suspect a problem with your serial interface on the 2610. It may be why it was ebay in the first place.

kryolla

also try to move the wic to slot 1 and see if the problem follows it then I would bet it is the wic card and not a slot issue.

conundrum

Finally got this working, thanks to those who gave their time to help.

As suggested by Kyrolla I moved the module to a different slot, and Voila, it worked. I got a link light immediately, and on doing a Show Ip Int Brief command I got UP Down on that link.

I then did a Shutdown, followed by a No Shutdown on that interface, and it changed to UP UP. I can now ping from one end of my little network to the other, all is well.

So it looks like the fault lies with the module slot....

GT-Rob

Yeah that can be a common problem. I have a 2600 that doesn't even recognize the card in one of the slots.

Better open a TAC case and get an RMA going! Hope you have a current service contract! :P