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PPPoE doesn't work with MPLS on 750x

We use some number of 720x and 750x routers, connected via Catalysts switches. Each router

configured as PPPoE access concentrator, and, at the same time, as an MPLS LSR. Frames to static routes,

connected to interfaces of routers, are switched

by means of MPLS. But not the same for PPPoE.

If I configure "tag-switching advertise-tags" on

750x routers all PPPoE trafic destined to their PPPoE clients stops. For example, ping from 720x router to PPPoE client connected to 750x router doesn't pass.

But in reverse direction - from the same 750x to PPPoE client on 720x - all pings passes !

IOS versions rsp-jk8o3sv-mz.122-13a.bin and

c7200-jk8o3s-mz.122-13a.bin, MPLS MTU = 1508.

MTU on Catalysts configured to maximum possible, from 1530 to 2018.

Community Member

Re: PPPoE doesn't work with MPLS on 750x

It seems there is no issue in the MPLS. Looks like the issue is in PPPOE. You can check the MTU size and if you are doing cloning (virtual template) to create virtual interfaces, you can disable that and check it out.

Troubleshooting MTU Size in PPPoE Dialin Connectivity

Adjusting IP MTU, TCP MSS, and PMTUD on Windows and Sun Systems

Community Member

Re: PPPoE doesn't work with MPLS on 750x

Your guess doesn't explain why it works in one direction and doesnt't work in reverse direction.

PPPoE and Virtual-Template configurations on all

access-concentrators are the same.

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