Netgear XCM8806 - 8800 SERIES 6-SLOT CHASSIS SWITCH 사용자 설명서
Chapter 5. Configuring Slots and Ports on a Switch
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NETGEAR 8800 User Manual
To enable jumbo frame support, enable jumbo frames on the desired ports. To set the
maximum jumbo frame size, use the following command:
maximum jumbo frame size, use the following command:
configure jumbo-frame-size <framesize>
The jumbo frame size range is 1523 to 9216. This value describes the maximum size of the
frame in transit (on the wire), and includes 4 bytes of CRC plus another 4 bytes if 802.1Q
tagging is being used.
frame in transit (on the wire), and includes 4 bytes of CRC plus another 4 bytes if 802.1Q
tagging is being used.
Set the MTU size for the VLAN by using the following command:
configure ip-mtu <mtu> vlan <vlan_name>
Next, enable support on the physical ports that will carry jumbo frames using the following
command:
command:
enable jumbo-frame ports [all | <port_list>]
Path MTU Discovery
NETGEAR 8800 switches support path MTU discovery.
Using path MTU discovery, a source host assumes that the path MTU is the MTU of the first
hop (which is known). The host sends all datagrams on that path with the “don’t fragment”
(DF) bit set which restricts fragmentation. If any of the datagrams must be fragmented by a
NETGEAR switch along the path, the NETGEAR switch discards the datagrams and returns
an ICMP Destination Unreachable message to the sending host, with a code meaning
“fragmentation needed and DF set”. When the source host receives the message
(sometimes called a “Datagram Too Big” message), the source host reduces its assumed
path MTU and retransmits the datagrams.
hop (which is known). The host sends all datagrams on that path with the “don’t fragment”
(DF) bit set which restricts fragmentation. If any of the datagrams must be fragmented by a
NETGEAR switch along the path, the NETGEAR switch discards the datagrams and returns
an ICMP Destination Unreachable message to the sending host, with a code meaning
“fragmentation needed and DF set”. When the source host receives the message
(sometimes called a “Datagram Too Big” message), the source host reduces its assumed
path MTU and retransmits the datagrams.
The path MTU discovery process ends when one of the following is true:
•
The source host sets the path MTU low enough that its datagrams can be delivered
without fragmentation.
•
The source host does not set the DF bit in the datagram headers.
If it is willing to have datagrams fragmented, a source host can choose not to set the DF bit in
datagram headers. Normally, the host continues to set DF in all datagrams, so that if the
route changes and the new path MTU is lower, the host can perform path MTU discovery
again.
datagram headers. Normally, the host continues to set DF in all datagrams, so that if the
route changes and the new path MTU is lower, the host can perform path MTU discovery
again.
IP Fragmentation with Jumbo Frames
The NETGEAR 8800 series switches support fragmentation of IP packets.
The switch supports the fragmenting of IP packets. If an IP packet originates in a local
network that allows large packets and those packets traverse a network that limits packets to
a smaller size, the packets are fragmented instead of discarded.
network that allows large packets and those packets traverse a network that limits packets to
a smaller size, the packets are fragmented instead of discarded.
This feature is designed to be used in conjunction with jumbo frames. Frames that are
fragmented are not processed at wire-speed within the switch fabric.
fragmented are not processed at wire-speed within the switch fabric.