VLL Service Configuration Commands
Page 332 7750 SR OS Services Guide
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.
P binding operational states are automatically re-evaluated.
For i-VPLS and EPIPEs bound to a b-VPLS, the service-mtu must be at least 18 bytes smaller than
the b-VPLS service MTU to accomodate the PBB header.
Because this connects a Layer 2 to a Layer 3 service, adjust either the service-mtu under the Epipe
service. The MTU that is advertised from the Epipe side is service-mtu minus EtherHeaderSize.
By default if no service-mtu is configured it is (1514 - 14) = 1500.
The no form of this command returns the default service-mtu for the indicated service type to the
default value.
Default apipe, fpipe: 1508
ipipe: 1500
epipe: 1514
The following table displays MTU values for specific VC types.
octets — The size of the MTU in octets, expressed as a decimal integer, between 1 — 9194.
SAP VC-Type Example
Service MTU
Advertised
MTU
Ethernet 1514 1500
Ethernet (with preserved dot1q) 1518 1504
VPLS 1514 1500
VPLS (with preserved dot1q) 1518 1504
VLAN (dot1p transparent to MTU value) 1514 1500
VLAN (Q-in-Q with preserved bottom Qtag) 1518 1504
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