3 configuring jumbo frames, Configuring jumbo frames -4, Section 11.3, "configuring jumbo frames – Riverstone Networks WICT1-12 User Manual

Page 182

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11-4 Riverstone Networks RS Switch Router User Guide Release 8.0

Configuring Jumbo Frames

IP Routing Configuration Guide

If you don’t specify which address to borrow, then the first address of ‘int1’ is borrowed.

Note

This feature cannot be used with multicast routing.

11.3

CONFIGURING JUMBO FRAMES

Certain RS line cards support jumbo frames (frames larger than the standard Ethernet frame size of 1518 bytes).

To transmit frames of up to 65535 octets, you increase the maximum transmission unit (MTU) size from the default
of 1522. You must set the MTU at the port level with the

port set mtu

command. You can also set the MTU at the

IP interface level; if you set the MTU at the IP interface level, the MTU size must be less than the size configured for
each port in the interface. Note that the interface MTU only determines the size of the packets that are forwarded in
software.

In the following example, the ports gi.3.1 through gi.3.8 are configured with an MTU size of 65535 octets. Ports gi.3.1
through gi.3.4 are configured to be part of the interface ‘int3,’ with an MTU size of 65000 octets.

If you do not set the MTU at the interface level, the actual MTU of the interface is the lowest MTU configured for a
port in the interface. In the following example, port gi.3.1 is configured with an MTU size of 50022 octets while ports
gi.3.2-8 are configured with an MTU size of 65535 octets. The interface MTU will be 50000 octets (50022 octets
minus 22 octets of link layer overhead).

rs(config)# port set gi.3.1-8 mtu 65535

rs(config)# vlan create JUMBO1 ip

rs(config)# vlan add ports gi.3.1-4 to JUMBO1

rs(config)# interface create ip int3 mtu 50000 address-netmask 10.20.3.42/24

vlan JUMBO1

rs(config)# port set gi.3.1 mtu 50022

rs(config)# port set gi.3.2-8 mtu 65535

rs(config)# vlan create JUMBO1 ip

rs(config)# vlan add ports gi.3.1-4 to JUMBO1

rs(config)# interface create ip int3 address-netmask 10.20.3.42/24 vlan

JUMBO1

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