Cisco Multilink PPP Issue

You are using the first software revison of a new IOS release - not a good plan.

Either upgrade to latest 12.4 or even better downgrade to latest 12.3

I downgraded to 12.3 and have the same issue. I don't think it's the IOS version that is the problem.

Try these (one at a time or all at once):

debug ppp authentication debug ppp negotiation debug ppp multilink debug ppp error debug ppp packet

Or even:

debug serial (whatever)

Might show something.

--Mag

Remove the ppp chap from the config. I've set up dozens of MPPP connections (including one yesterday) and have never used ppp chap. Also upgrade to the latest 12.4 T release. The end-of-sale & end-of-life was announced for a large portion of 12.3T today.

If that doesn't fix it open a TAC case. They'll have the problem sorted out in an hour or two.

| I am attempting to configure two T1's using MLPPP on a Cisco 1841 | running IOS 12.4(1a). I have two WIC-1DSU-T1-V2 cards connected to two | T1's at my ISP. The ISP says that the MLPPP is configured correctly on | their end, and I'm trying to configure my end to get all the interfaces | up. Without the interfaces in the Multilink Group, both T1's are | up/up, but when adding the two serial interfaces to the Multilink | Group, the first one added always goes to up/up, but the second | interface to be added (it doesn't matter which interface) always goes | to up/down. I am not able to get up/up on all interfaces. Am I | missing something? Basically, I can only get one serial interface to | become an active member in the bundle at any given time. | | Below is a copy of the relevant parts of my config. My ISP is telling | me that I need to call Cisco because it is a problem with my router or | my IOS. Is this the case? If anyone has any insight it would be | greatly appreciated. | | SH RUN: | interface Multilink1 | ip address x.x.x.x x.x.x.x | ppp chap hostname group1 | ppp multilink | ppp multilink fragment disable | ppp multilink group 1

How about adding:

ppp multilink links minimum 2

Dan Lanciani ddl@danlan.*com

Is "ppp multilink group 1" command required under the interface Multilink 1

I would have thought that it is only required on the serial interfaces.

Yes.

Cisco in general doesn't assume multilink group 1 should belong to interface Multilink 1. You could create multilink group 385 and assign it to Multilink interface 14 if you wish.

Thank you all for your responses. After running the suggested debug commands I was able to pinpoint the problem. Go figure....I had to call my ISP and painstakingly try to convince them that they had incorrectly configured one of the serial interfaces on their end. After much reluctance they finally admitted to having typed a command on one interface and not the other. Thanks for your help.

out of curiousity what did you see in the debugs and what did the ISP have to change ?

I saw that when trying to add the second link to the bundle, it told me that it couldn't add the link because the bundle names didn't match. So looking at both links separately, I noticed that each of my serial interfaces was picking up a different group name from each of their serial interfaces, and the debug was telling me that the names had to match in order to be in the same bundle. After begging them (they insisted there was nothing wrong on their end and that it was a problem with my router) to humor me and go check to make sure the configuration was identical on both of their interfaces, they finally came back and told me that they had entered the correct group name on one interface and left out that command on the other.