PLANET WGS3-24240 - Manual (Page 479)

User’s Manual of WGS3-24000 / WGS3-24240
479
12.2.17 ip mtu
This command sets the IP Maximum Transmission Unit (MTU) on a routing interface. The IP MTU is the size of the largest IP
packet that can be transmitted on the interface without fragmentation.
FASTPATH software currently does not fragment IP packets.
Packets forwarded in hardware ignore the IP MTU.
Packets forwarded in software are dropped if they exceed the IP MTU of the outgoing interface.
Packets originated on the router, such as OSPF packets, may be fragmented by the IP stack. The IP stack uses its default IP
MTU and ignores the value set using the ip mtu command.
OSPF advertises the IP MTU in the Database Description packets it sends to its neighbors during database exchange. If two
OSPF neighbors advertise different IP MTUs, they will not form an adjacency. (unless OSPF has been instructed to ignore
differences in IP MTU with the ip ospf mtu-ignore command.)
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Note : The IP MTU size refers to the maximum size of the IP packet (IP Header + IP payload). It does not include any extra
bytes that may be required for Layer-2 headers. To receive and process packets, the Ethernet MTU (See “mtu” on
page 17.) must take into account the size of the Ethernet header.
▫ Default 1500 bytes
▫ Format ip mtu <68-1500>
▫ Mode Interface Config
12.2.18 no ip mtu
This command resets the ip mtu to the default value.
▫ Format no ip mtu <mtu>
▫ Mode Interface Config
12.2.19 encapsulation
This command configures the link layer encapsulation type for the packet. The encapsulation type can be ethernet or snap.
▫ Default ethernet
▫ Format encapsulation {ethernet | snap}
▫ Mode Interface Config