MTU configuration for EoMPLS

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Sep 14th, 2010
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Scheme is:


Equipment is: PE & P - are 7606,7609.

PE-to-Client interfaces are 10GigEthernet.

PE-to-P interfaces are port-channels made up from also 10GigEthernet ifaces with mtu set to 9000.

All PE and P have system jumbomtu 9000 set globally

PE-to-Clinet interfaces are used for port-based EoMPLS. Client interfaces are 802.1q trunks.So this is a point-to-point topology.

Is it necessary to indicate mpls mtu and mtu on PE-to-Client interfaces or global setting (system jumbomtu 9000) is used?

Correct, please, my understanding of the proccess:

Encapsulation looks like this:

[802.3 header] [802.1q tag] [MPLS label] [IP header] [Clients payload]

802.3 header - 14 bytes

802.1q tag - 4 bytes (the mpls packet traverses between PE's in a vlan)

MPLS label - 4 bytes (in my case for point-to-point topology only 1 label is used)

IP header - 20 bytes (contains IP addresses for xconnect points of PE's)

Client payload - A full client's frame that contains 14 bytes 802.3 header, 4 bytes 802.1q tag(or 8 bytes q-in-q tag), and payload (IP or whatsoever).

Thanks, Alex.

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