DCE's

Can a Router be the DCE on more than one interface. Reason for asking.. I'm working on the CCENT material and decided to have one (2507) router act as the DCE and connect 2 other DTE's (2621, 2610xm) to it. However, when I do one interface always goes down with a line protocol error. I verified the settings against the working interface and their the same. The keep alives are there, clock rate is set, encapsulation type matches, LMI I believe is not an issue as I'm not trying Frame relay yet. The opposite end, DTE side shows up/up.. So I'm convinced it's the 2507.

The part that throws me is, when I just have one interface on the 2507 act as the DCE and change the interface on the 2621 to DCE from DTE the connections are good.

In others words the 2507 appears to be able to handle one DCE connection only.

Is this a hardware limitation of the older model I'm using or a common thing where a router can act as a DCE on just one interface. I've checked my reading material and can't find anything. The web is great for telling you how to set it up, but I haven't found the answer to this one yet...

Thanks again folks.

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Comments

blackninja

You can have as many DCE interfaces as you want, as long as you set clock rate on the DCE.

Make sure the cables are the right way around, e.g. DCE end plugged into the DCE interface.

Make sure ip addresses on both ends are in the same subnet, each cable must be in it's own subnet.

Encap ppp on both sides
set clock on DCE side only .
make sure you "no shutdown" all interfaces.

run "show controllers serial X " to show type of cable and if clock has been set

All should work

joe48184

blackninja wrote: »

Make sure ip addresses on both ends are in the same subnet, each cable must be in it's own subnet.All should work

Thanks for the reply.. are you saying that the 2507 router with serial0 and serial1 need to be on the same subnet (which they currently are) and the routers I'm connecting to are on a diferent subnets (again, they currently are).

I'm workign on a lab of my own doing.. I have 3 routers, the 2507 with serial0 connected to a 2621, and serial1 connected to a 2610xm.

Where I'm currently at is the 2507 can ping the fa0/1 interface of the 2621 and the 2610 and the switches attached to them. The 2621 and the 2610 can "not" ping each other but they can ping the 2507 and its switch. The 2507 has static routes to the other 2 routers. Think of the 2507 as the middle router and the 2621 / 2610 as the ones to the right and left of it.

I'm fairly sure I have a routing issue, but then again if I didn't configure the serial interfaces on the 2507 properly, my problem is more than just routing.

Kaminsky

The DCE is layer 1 and has no idea about layer 3 IP, subnets, etc. The fact you can ping, means layers 1 & 2 are working. You can have x serial interfaces and mix and match dce/dte, it makes no difference as long as you put the clocking in the right place for that particular link.

If you are using PPP to encapsulate, that will put an <ip address of remote interface> /32 (exact IP address match ) into the routing table when IPCP goes open so you will be able to ping the serial interface on the other end of that link but not necessarily the rest of the interfaces on that router if either end's subnets are mismatched. As you are able to ping beyond that to other devices on FA connections, it suggests you have a routing issue in the centre on the 2507. I think the problem lies with your static routes from one interface to the other on the 2507.

blackninja

Try this:

Download http://www.techexams.net/forums/ccna-ccent/42260-ccna-lab-workbook.html and goto page 30 and follow the Configure PPP lab

A very good book to help is: CCNA Portable Command Guide

joe48184

blackninja wrote: »

Try this:

Download http://www.techexams.net/forums/ccna-ccent/42260-ccna-lab-workbook.html and goto page 30 and follow the Configure PPP lab

A very good book to help is: CCNA Portable Command Guide

Thats where I go the idea, page 27 - 30 add a router and switch in the middle.

I'm working on it... I'll get it.

bigheadx

Joe,

The interfaces do not have to be in the same subnet.

As the others said, make sure the connection is firm, and you have the DCE side of the cable plugged in.

Id go like this,

Config term
int s0/0
ip address 192.168.1.1 255.255.255.0
no shut
clockrate 9600

int s0/0
ip address 192.168.2.1 255.255.255.0
no shut
clockrate 9600

I was doing a tunneling lab where my protocol was bouncing, and come to find out it was the cable.