cấu hình MTU và Jumbo Frame cho switch Dell Force10 S4810

cấu hình MTU và Jumbo Frame cho switch Dell Force10 S4810

https://www.force10networks.com/CSPo...-settings.aspx


Adjusting MTU and Configuring Jumbo Frame Settings
Overview
This tech tip explains the function of different Maximum Transmission Unit (MTU) settings in FTOS. Also, it provides an example of configuring jumbo frames and adjusting MTU settings.
MTU and IP MTU Settings
FTOS uses:

• MTU settings to determine whether or not to fragment a packet
• IP MTU settings to set the packet fragment size

The difference between the MTU and IP MTU settings should be equal to the Ethernet header and footer size (18 bytes for untagged ports and 22 bytes for tagged ports). FTOS automatically sets the IP MTU equal to the MTU less 18 bytes (IP MTU = MTU – 18 bytes) when you configure a MTU setting. If you use a tagged port, the user needs to set the IP MTU equal to the MTU less 22 bytes (IP MTU = MTU – 22 bytes).


Port Type
IP MTU Calculation
Untagged Port
IP MTU = MTU – 18 bytes
Tagged Port
IP MTU = MTU – 22 bytes


Example
If you set the MTU to 9000 for an untagged port, you should set the IP MTU should be set to 8982 (MTU – 18 bytes). (FTOS configures this automatically.)
If MTU is set to 9000 for a tagged port, the IP MTU should be set to 8978 (MTU – 22 bytes). (You must configure this value.)



For port channel and VLAN interfaces, all member ports should have the same MTU and IP MTU values. If you configure the MTU and IP MTU on a port-channel or VLAN interface, FTOS does not configure MTU and IP MTU on the member ports automatically. You must configure them for the individual members.
If the VLAN or port channel is a Layer 3 interface (if you assign the IP address), then you should configure the MTU and IP MTU on those interfaces. The OSPF, BGP, IS-IS and the IP Stack use these configured values.
Devices on the same physical subnet should have the same MTU and IP MTU settings to ensure the proper operation of the protocol. For Jumbo frame purposes, FTOS sets an interface’s Maximum Receive Unit (MRU) size equal to the MTU value you configured for the interface (MRU = MTU).
Force10 TAC is aware that other vendors implement MTU differently. For more information about your situation, please consult your vendor’s documentation.
Example Configuration
Here is a sample configuration you can use to set up MTU and IP MTU settings to work with Jumbo frames:
1) All currently shipping Force10 line cards and RPMs support Jumbo frames. On the E-Series and C-Series, you can verify that your RPMs and line cards support Jumbo frames by using the show linecard and show rpm commands to inspect the Jumbo Capable field for the value "yes", as shown below. On the S-Series, see the Jumbo Capable field in the output of the command show system stack-unit.





Force10# show rpm
-- RPM card 0 --
Status : active
Next Boot : online
Card Type : RPM - Route Processor Module (LC-EF-RPM)
Hardware Rev : 2.0
Num Ports : 1
Up Time : 36 min, 51 sec
Last Restart : reset
FTOS Version : 6.2.1.0
Jumbo Capable : yes
---[output truncated]---------------





2) All currently shipping Force10 chassis support Jumbo frames. Some E-Series using EtherScale architecture do not by default. To check if your E-Series is Jumbo-enabled, use the show chassis command:



Force10# show chassis
-- Manufacturing Info --
Chassis Type : E1200
Chassis Mode : TeraScale
---[output truncated]---------------



Your Chassis Mode must be set to anything but “Non Jumbo”.
Note: You can also inspect the Jumbo capability of the RPMs in the output of this command.
3) Check current MTU settings:



Force10# show interfaces gigabitethernet0/0
GigabitEthernet 0/0 is down, line protocol is down
Hardware is Force10Eth, address is 00:01:e8:05:ae:e5
Internet address is not set
MTU 1554 bytes, IP MTU 1500 bytes
LineSpeed auto, Mode full duplex
ARP type: ARPA, ARP Timeout 04:00:00





4) Configure interface MTU/IP MTU:



Force10# configure
Force10(conf)# interface gigabitethernet 0/0
Force10(conf-if-gi-0/0)# mtu 9252
Force10(conf-if-gi-0/0)# ip mtu 9234
Force10(conf-if-gi-0/0)# show config
!
interface GigabitEthernet 0/0
no ip address
mtu 9252
ip mtu 9234
shutdown
Force10(conf-if-gi-0/0)#Force10#



5) Verify new settings:



Force10#show interfaces gigabitethernet0/0
GigabitEthernet 0/0 is down, line protocol is down
Hardware is Force10Eth, address is 00:01:e8:05:ae:e5
Internet address is not set
MTU 9252 bytes, IP MTU 9234 bytes
LineSpeed auto, Mode full duplex
ARP type: ARPA, ARP Timeout 04:00:00