WAN Serial connection ...First timer

I am connecting two 2500 series routers. Router A on S0 and Router B on S0. I am using a high density serial DTE to serial DCE 3ft cable.

I am not using a V.35 DTE / DB60 to 34-pin male connected to a V.35 DCE/ DB60 to female 34-pin as recomended.

I configured my serial interfaces correctly, I think. When I run 'show IP route' I only have Eth 0 connected and serial 0 doesn't show. I cant ping either.

I assumed my 3 ft cable would be electricaly the same. What am I doing wrong?

Zooman

Find more posts tagged with

Save $250 on 2025 certification boot camps from Infosec!

Book now with code EOY2025

Button

Comments

mwgood

zooman wrote:

What am I doing wrong?Zooman

Hard to say given only this information. You might try a "show run" so we can see your running-config - that would give us more to go on.

Need to see that your serial interfaces are UP, DTE/DCE set correctly with clock rate, and that the IP's are configured correctly.

wildfire

When connecting router back to back, on of the routers has to be configured with timing (DTE I think) so try adding the following commands

Conf t
int s0
clock rate 10000000
ctrl Z

forbesl

wildfire wrote:

When connecting router back to back, on of the routers has to be configured with timing (DTE I think) so try adding the following commands

Conf t
int s0
clock rate 10000000
ctrl Z

Actually, the router on the DCE side needs to have the clock statement input.
If you're unsure which side that is, type in "sh controllers interface serial 0". That will tell you whether you have a DTE or DCE connection on that interface.

You don't need to input a high clock rate on the interface for your lab, "clock rate 64000" will do just fine. If you're unsure of the clock rates you can input on your serial interface, go into interface configuration mode and type "clock rate ?", and you can find out what clock speeds you will be able to use. I could be wrong, but I don't believe "clock rate 10000000" will work, as the serial interfaces on a Cisco 2500 router are 1544K interfaces.

keenon

he also needs to enable the serial interface.. with "no shut" what type of connection frame or ppp..

what are the serial interface configs? routing protocol?

forbesl

keenon wrote:

he also needs to enable the serial interface.. with "no shut" what type of connection frame or ppp..

I figured the "no shut" would be a "no brainer". As far as the encapsulation (type of connection), he can use the default encapsulation, which is HDLC. No need to change the encapsulation unless you are setting up a scenerio specifically for frame relay or ppp. A direct router-to-router serial connection for a lab needs no change in the encapsulation.

wildfire

I use clock rate 1000000 on my home lab as this clock rate is not proportinal to the bandwitdh bandwidth , bandwidth statement used for that, I found with a clock rate of 64,000 that I was getting crc errors on a back to back when putting high data rates through ie T1. Howver I aslo found that I used that clock rate on a 1603 with no much ram and it crashed rather quickly!

keenon

forbesl wrote:

keenon wrote:

he also needs to enable the serial interface.. with "no shut" what type of connection frame or ppp..

I figured the "no shut" would be a "no brainer". As far as the encapsulation (type of connection), he can use the default encapsulation, which is HDLC. No need to change the encapsulation unless you are setting up a scenerio specifically for frame relay or ppp. A direct router-to-router serial connection for a lab needs no change in the encapsulation.

reason i asked that i wanted to know if he was doing something other than basic plug it up. also when i mentioned no shut is that if it is his first lab setup he should know all interfaces are off by default.

now zooman can you show your current running config

forbesl

keenon wrote:

reason i asked that i wanted to know if he was doing something other than basic plug it up. also when i mentioned no shut is that if it is his first lab setup he should know all interfaces are off by default.

Yeah, you're right. Didn't mean to offend.

zooman

I was way off. The serial cable works fine. It was my config.

I used the TECH EXAM CCNA TechLab: 1 Configuring a RIP network. I am about 90% there. (Using this example as my topic of discussion...)

I have established conectivity from Host A accros the serial /WAN 192.168.22.0 to RouterB S0 192.168.22.6.

Can I assume that my DCE cable(RouterB) and 'clock rate' are configured correctly?

I suspect that the problem is on RouterB. When I configure 'ROUTER RIP'
Version 2 the command prompt returns to just RouterB# an doesn't remain in the CONFIG mode for RIP. So my Network 192.168.22.0 & 192.168.33.0 for RIP may not be valid.

Problem
I can not ping th LAN of RouterB E0 /192.168.33.1 from HostA. I suspect that I have an issue with my RIP / Network assicnment. Is there some detail I am missing?

mwgood

zooman wrote:

Is there some detail I am missing?

If your S0 on Router A has it's IP set to 192.168.22.0 - that's a problem, being that that would be the network address. Try setting it to 192.168.22.1 or something other than the network address.

As long as you have enabed S0 on Router B and set your clock rate and the IP address is 192.168.22.6, then it should be ok. RIP shouldn't be a factor when you try to ping from one serial interface to another since they are on the same network. RIP is important when you try to ping to another network.

Also, there is no need to use version 2 of RIP.

Once your interfaces are setup correctly, then your RIP commads should be:

RouterA:
router rip
network 192.158.22.0

RouterB:
router rip
network 192.158.22.0
network 192.168.33.0

schneeman

zooman wrote:

I was way off. The serial cable works fine. It was my config.

I used the TECH EXAM CCNA TechLab: 1 Configuring a RIP network. I am about 90% there. (Using this example as my topic of discussion...)

I have established conectivity from Host A accros the serial /WAN 192.168.22.0 to RouterB S0 192.168.22.6.

Can I assume that my DCE cable(RouterB) and 'clock rate' are configured correctly?

I suspect that the problem is on RouterB. When I configure 'ROUTER RIP'
Version 2 the command prompt returns to just RouterB# an doesn't remain in the CONFIG mode for RIP. So my Network 192.168.22.0 & 192.168.33.0 for RIP may not be valid.

Problem
I can not ping th LAN of RouterB E0 /192.168.33.1 from HostA. I suspect that I have an issue with my RIP / Network assicnment. Is there some detail I am missing?

Here's your answer.
Router A
enable
Configure terminal
interface serial 0
ip address bla bla
no shutdown
clock rate 64000 ' or whatever else
interface ethernet 0
ip address bla bla bla
no shutdown
exit
router rip
network (subnet of ethernet0)
network (subnet of serial 0)
ctrl+z
copy running-config startup config

Router B
enable
configure terminal
interface serial 0
ip address bla bla ( ip address must be the same subnet of Router A S0)
no shutdown ' you dont need clock rate command in here.Clock rate 'command only use for DCE side not DTE side.
interface ethernet 0
ip address bla bla bla
no shutdown
exit
router rip
network (subnet of ethernet 0)
network (subnet of serial 0)
copy running-config startup-config
' "and use show ip" route command check for the routing path
' "show controller" command to which serial interface is DTE or DCE
' "show interface" command and look for serial is up/down or line protocol is up/down.
You dont need any encapsulation process in here.Default is using HDLC for cisco.
And of course dont forget if you use VLSM(different subnet mask principle) you must use rip version 2 instead of rip.Because rip version 1 dont support VLSM.
here is the configuration for rip version 2
router rip
version 2
network ..... same of above
Good Luck....

zooman

Thanks for all the input.

I finally got it working.

Hard to say exactly what it was ...
when configuring 'Router RIP' the prompt wouldnt stay in (config-router) mode after I enter 'version 2'

Attention to detail.... First serial connection up and running.

schneeman

Good for you then