How to do IPL connection using Cisco 2801 router to Cisco 1841

[mister_sai]

Hi,

I  need some clarification if it is possible to do an IPL connection  between Cisco 2801 (T1) to Cisco 1841 (E1) via Ethernet (2801) to Serial  (1841).

I am unable to find any documentation about this and I need to connect our network to our overseas office.

Our side uses the 1841 router and our provider has set-up our E1 connection to be via Serial interface while on our overseas office uses the 2801 and will connect via the T1 card, which by  the way does not have any serial interface ports just ethernets.

So far checking on how to configure this, I am unsure on how the connection will happen since the info that I got is that T1 does not have the option to hold an IP address (also unsure on this though). With this in mind and that the 2801 does not have serial interfaces, does that mean that IPL connection would be via the available Ethernet ports?

If possible can someone please provide a sample configuration for both routers.

TIA!

[Giuseppe Larosa]

Hello Sergio,

the T1 has to be terminated on a WAN interface, the cabling may look like an ethernet port as E1 or T1 interfaces may have an RJ-45 connector but they are not ethernet interfaces.

IF the 2801 really misses the T1 port you need to add a WAN module to your router.

You can check with

show version

show hardware

what type of interfaces are on the C2801.

Feel free to post the output of the show command

By the way, what do you mean with IPL connection?  Is it the name of a service of the WAN provider?

or simply IP layer connection?

Hope to help

Giuseppe

[mister_sai]

Hi Giuseppe,

IPL = international private leased

Here's what I have on the 2801 :

version 12.4

controller T1 0/0/0

framing esf

linecode b8zs

cablelength long 0db

!

!

controller T1 0/1/0

framing esf

linecode b8zs

cablelength long 0db

!

!

!

!

!

interface FastEthernet0/0

no ip address

no ip route-cache

shutdown

duplex auto

speed auto

!

interface FastEthernet0/1

no ip address

no ip route-cache

shutdown

duplex auto

speed auto

Basically, we are trying to do an interconnect to an overseas network. Our side has the Cisco 1841 router while the Cisco 2801 is located overseas.

From my understanding on this, configuration should just be assigning IP addresses on both routers that is on the same subnet but as of now we are unable to communicate with the 2801 and vice versa.

Thanks.

[Giuseppe Larosa]

Hello Sergio,

>>From my understanding on this, configuration should just be assigning IP addresses on both routers that is on the same subnet

This is needed, but it is not enough.

Controller T1 are physical layer objects are not L3 interfaces you need to derive a serial interface object that can be used to assign an IP address

example:

controller t1 0/0/0

channel-group 0 unframed

or

channel-group 0 timeslots 1-23

will create a serial interface ser0/0/0:0   (notice the notation : followed by the channel-group number)

the interface so created can be configured with an IP address and it has default Cisco HDLC encapsulation

The same has to be done on the E1 side keeping in mind that E1 has 31 timeslots

also on the controller e1 side you will create a serial interface. The two serial interfaces must share the same IP subnet and layer 2 encapsulation.

Hope to help

Giuseppe

[Jeff Van Houten]

Assuming the t1 is plugged to one of the controller connections, you need to add a channel-group command. That will create the serial interface you are looking to attach an IP address to.

Sent from Cisco Technical Support iPad App

[mister_sai]

Hi Giuseppe and Jeff,

Thanks a lot for your help. I will try to ask our overseas office to do these and will keep you posted on the result. Hopefully this will do the trick.

Just one last thing though, our Cisco 1841 is already connected via serial interface and also it does not have an E1 interface. It doesn;t have the option of setting the timeslots. Will this affect the connectivity?

Here's what I have for our Cisco 1841 :

version 12.4

interface FastEthernet0/0
  description $ETH-LAN$$ETH-SW-LAUNCH$$INTF-INFO-FE 0$

no ip address

  duplex auto

  speed auto

!
interface FastEthernet0/1
  no ip address
  duplex auto
  speed auto
!
interface Serial0/0/0
  no ip address
  shutdown
  clock rate 2000000
!
interface Serial0/0/1

no ip address

  shutdown

  clock rate 2000000

Thanks again.

[Giuseppe Larosa]

Hello Sergio,

ok the C1841 has a serial interface inside the WAN service provider a conversion is performed and the service can be provided to the two endpoints as a data stream.

It shouldn't be a problem check with them what channel-group option ( unframed or timeslots 1-23) they would like to be configured

Hope to help

Giuseppe

[mister_sai]

Hi guys,

Thanks for the help with this. I already did all the steps that you provided but I'm still having some problems. I don't want to pass this yet to the provider until I can eliminate internal issues or if I still have some tinkering that I can do on my end. I attached a copy of the configuration that we have, our's (C1841)  and our overseas office (C2801). 

Our connection between the two offices uses the 192.168.105.0 / 30 subnet.

I just did a default route (ip route 0.0.0.0 0.0.0.0 192.168.105.X) for both routers than doing static route just in case that there will be changes with the internal network.

Anyway, with the configuration that we have on our C1841, when I do "show ip ip route" command it shows that the default gateway is the

192.168.105.1 (C2801 ip address, see ipro.jpg) address but when I do the same command on the C2801 it does not show our C1841 IP address (see ip ro.jpg).  As you can see on the attachments that the output looks different for each router, plus, on "ip ro" it has "ICMP redirect cache is empty" which is a first for me to see.

Lastly, when I do "show ip interface brief" on C2801, it listed that the S0/1/0:0 interface as "DOWN" for both "status and prot". Just to add it shows "UP" for our C1841 router.

As of now, based from my understanding, I'm thinking that the reason that it shows as "DOWN" means that there might be some configuration that the provider for our overseas office needs to do, but I could be wrong .

Thanks in advance.

[mister_sai]

Hi,

I have attached the copy of running config, show int and show ip route outputs for both routers.

Maybe this would help on shedding some light on why the connection doesnt run.

Really need help on this.

Thanks!

[Giuseppe Larosa]

Hello Sergio,

first of all, there is a loop set on the C1841 side of the WAN link:

ICOMTEQ_IAS(config-if)#do sho int s0/0/1

>>>>Serial0/0/1 is up, line protocol is down (looped)<<<<

this means the circuit is not operational at the moment, unless you have performed an hardware loopback, no loopback is set on software

If you haven't used any special cable, it is the WAN SP that has set the loop for testing purposes.

interface Serial0/0/1

ip address 192.168.105.2 255.255.255.252

encapsulation ppp

autodetect encapsulation ppp

!

on the other router we see that ser0/1/0:0 is down / down this should be caused by controller t1 0/1/0 to be down.

However, the state of ser0/1/0:0 may be related to the fact that a loop is set on remote end.

You can check the state of the t1 controller with the command

show controller t1 0/1/0

Feel free to post the output

Another point to be noted is that you have a default route on the C1841 pointing to the C2801, but you have also a default route on the C2801 pointing to the C1841, this is not good practice. One side may provide internet access to the other side, but in the central office you should use a specific static route pointing to the other device.

From the C2801 side you should have

ip route 192.168.110.0 255.255.255.224 192.168.105.2

So you need to contact the WAN SP as the circuit is not operational in both sides: on C1841 side there is a loop and on the C2801 side the t1 controller is likely down/down. Cabling has to be checked on the C2801 side, generally you should use a straight on cable to connect the C2801 T1 port to the NT device.

Check with WAN SP people what type of cable has to be used. Be aware that a  T1 crossover cable is a special cable with different pinout then an ethernet cross-over cable.

Hope to help

Giuseppe

[mister_sai]

Hi,

regarding the s0/1/0:0 on down/down : it was my first thought that WAN SP needs to contacted. with show controllers t1 0/1/0 it does show that the controller is down, I attached the truncated output. Also I will have our engineers on site to verify the type of cable that is connected to the T1 controller.

About the default routes that I put in on both routers, my priority was to establish connection first and then adjust the routing tables after.

currently we are waiting for word from our SP, i already forwarded the same files to them.

Hopefully we can have this up and running within the week.

I really appreciate all the help...

Will keep you posted.

Thanks again.

[mister_sai]

Hi Giuseppe,

connection is still not working.

regarding T1 being down on C2801, we contacted the SP and they said that all lines are ok.

I was able to successfully do the software loopback from here. All tests return 100%

Need some help.

Thanks