H3C Technologies H3C S12500 Series Switches - Manual (Page 106)

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Configuring MTU for an interface
When a packet exceeds the MTU of the output interface, the device processes it in one of the following
ways:
• If the packet disallows fragmentation, the device discards it.
• If the packet allows fragmentation, the device fragments it and forwards the fragments.
Fragmentation and reassembling consume system resources, so set an appropriate MTU for an interface
based on the network environment to avoid fragmentation.
To configure an MTU for an interface:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Configure an MTU for the
interface.
ip mtu mtu-size By default, no MTU is configured.
101B
Configuring TCP MSS for an interface
The maximum segment size (MSS) option informs the receiver of the largest segment that the sender can
accept. Each end announces its MSS during TCP connection establishment. If the size of a TCP segment
is smaller than the MSS of the receiver, TCP sends the TCP segment without fragmentation. If not, it
fragments the segment according to the receiver's MSS.
If you configure a TCP MSS on an interface, the size of each TCP segment received or sent on the
interface cannot exceed the MSS value.
This configuration takes effect only for TCP connections established after the configuration rather than the
TCP connections that already exist.
This configuration is effective only for IP packets. If MPLS is enabled on the interface, do not configure the
TCP MSS on the interface.
To configure a TCP MSS of the interface:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Configure a TCP MSS for the
interface.
tcp mss value By default, the TCP MSS is 1460 bytes.
102B
Configuring TCP path MTU discovery