Alcatel-Lucent 7750 SR OS Service Manual page 240

Service router - mobile gateway

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VLL Service Configuration Commands

config>service>epipe

config>service>apipe

config>service>fpipe

config>service>ipipe

This command configures the service payload (Maximum Transmission Unit – MTU), in bytes, for

the service. This MTU value overrides the service-type default MTU.

The service-mtu defines the payload capabilities of the service. It is used by the system to validate

the SAP and SDP binding's operational state within the service.

The service MTU and a SAP's service delineation encapsulation overhead (i.e., 4 bytes for a dot1q

tag) is used to derive the required MTU of the physical port or channel on which the SAP was created.

If the required payload is larger than the port or channel MTU, then the SAP will be placed in an

inoperative state. If the required MTU is equal to or less than the port or channel MTU, the SAP will

be able to transition to the operative state.

When binding an SDP to a service, the service MTU is compared to the path MTU associated with the

SDP. The path MTU can be administratively defined in the context of the SDP. The default or

administrative path MTU can be dynamically reduced due to the MTU capabilities discovered by the

tunneling mechanism of the SDP or the egress interface MTU capabilities based on the next hop in

the tunnel path. If the service MTU is larger than the path MTU, the SDP binding for the service will

be placed in an inoperative state. If the service MTU is equal to or less than the path MTU, then the

SDP binding will be placed in an operational state.

In the event that a service MTU, port or channel MTU, or path MTU is dynamically or

administratively modified, then all associated SAP and SDP binding operational states are

automatically re-evaluated.

The no form of this command returns the default service-mtu for the indicated service type to the

default value.

apipe, fpipe: 1508

The following table displays MTU values for specific VC types.

octets — The size of the MTU in octets, expressed as a decimal integer.

Ethernet (with preserved dot1q)

VPLS (with preserved dot1q)

VLAN (dot1p transparent to MTU value)

VLAN (QinQ with preserved bottom Qtag)

7750 SR OS Services Guide