frame and cell mode

Unanswered Question
Jun 8th, 2007

MPLS has two types label method. Frame mode and cell mode. ATM can be either frame mode or cell mode according to the doc. How do I know the ATM is configured as frame or cell mode. Is there a default thing? thanks

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Harold Ritter Fri, 06/08/2007 - 08:07

Cell mode was defined for ATM and is the only mode supported by ATM switches.

That being said, MPLS frame mode can be configured over an ATM PVC, in which case your ATM network doesn't even need to be MPLS aware.

Hope this helps,

ciscoforum Fri, 06/08/2007 - 08:46

Hi Harold


Here is the configuration from our customer. 1.Could you tell me is this frame or cell mode?

2.Quoting what you said "in which case your ATM network doesn't even need to be MPLS aware". Is this MPLS aware or not? How to understand this?

interface ATM2/0/0.11 point-to-point

ip address

ip ospf network point-to-point

tag-switching ip

pvc 73/1052

Harold Ritter Fri, 06/08/2007 - 08:59

This is frame mode. In this case the ATM network doesn't need to be MPLS aware. It just transports MPLS as it would transport any other protocol, such as IPv4, IPv6 or IPX for that matter.

Hope this helps,

ciscoforum Fri, 06/08/2007 - 11:09

Thanks. Do you happen to have a configuration about to use cell mode for ATM? I want to see the configuration difference that may help me understand it better,

sasif Fri, 06/08/2007 - 21:51

Just add two things to determine quickly if the network is Cell or frame mode:

1. When you see the tag-switching in front of the ATM interface

2. When the Labels are VPI/VCI


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