MPLS Multilevel Labeling

Unanswered Question
Feb 12th, 2007

Waht's the max number of labels that can be inserted in a packet? Is there any link to read about that?


I have this problem too.
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alexander.muhin Mon, 02/12/2007 - 09:30


I think there is no hard mpls stack size limits except hardware limitations or MTU size of the interface.

hope this helps,


mheusinger Mon, 02/12/2007 - 09:36


potentially there can be as many labels as the MTU allows according to the standards. In reality you might have hardware based limitations like in the "Cisco IOS Software Configuration for the Cisco 12000 Series Two-Port OC-192c/STM-64c Packet over SONET Line Card"

MPLS and MPLS Class of Service

•MPLS label processing:

–Six labels maximum can be pushed per tagged packet (one of which is a replace if the packet is a tagged packet)

–Two labels maximum can be popped per packet.

So I would recommend to read through hardware specific guides, as theoretically there is only the MTU limit.

Regards, Martin

Ahmede Mon, 02/12/2007 - 11:31

Thanks for your response.. What type of labels can be inserted?

mheusinger Mon, 02/12/2007 - 13:24


there are only 4 Byte labels in frame-mode MPLS; they all look absolutely the same.

If your question is about the meaning of labels: there could be f.e. an MPLS TE label, a LDP label, a VPN label ... and more VPN labels! In a Carrier of Carriers environment there could be - possibly - any number of VPN labels, each belonging to a different service provider.

Regards, Martin


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