VLL Service Configuration Commands
Page 202 7210 SAS-X, R6 OS Services Guide
The service MTU is compared to the path MTU associated with an SDP before binding an SDP to a
service. The path MTU can be administratively defined in the context of the SDP. The default or
administrative path MTU can be dynamically reduced based on:
• The MTU capabilities discovered by the tunneling mechanism of the SDP.
• The egress interface MTU capabilities based on the next hop in the tunnel path.
If the service MTU is greater than the path MTU, the SDP binding for the service transitions to an
inoperative state. If the service MTU is equal to or less than the path MTU, the SDP binding
transitions to an operative state.
If a service MTU, path MTU or a channel MTU is dynamically or administratively modified, the
operational states of all associated SAP and SDP bindings are automatically re-evaluated.
The no form of the command restores the default service-mtu of the indicated service type to default
value.
Notes:
• To disable service MTU check, execute the command no service-mtu-check. Disabling service
MTU check allows the packets to pass to the egress if the packet length is lesser than or equal to
the MTU configured on the port. In 7210 SAS, length of the SAP tag (or service-delimiting tag,
for a packet received over a pseudowire) is included in the computation of the packet length
before comparing it with the service-MTU configured for the service.
Packet length= Length of IP packet + L2 header + length of SAP tag
• This command is supported only on 7210 SAS devices configured in Network mode. It is not
supported in access-uplink mode.
Default 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.
service-mtu-check
Syntax [no] service-mtu-check
Context config>service>epipe
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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