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oguarisco
Explorer

SUP 6T and MTU setting for Jumbo Framre

Dear all,

 

I'm trying to figure out the correct settings to enable Jumbo Frame on SUP 6T...

 

On SUP 6T you can only change MTU at Ethernet Frame L2 and not also at L3, isn't it?

 

I've noticed that system MTU is per default 9216 but PHY and SVI interface have per default 1500.

If I change/adapt MTU value on a SVI without modifying the PHY port/ports associated to that SVI, will the PHY port/ports inherit the MTU setting or it will be still 1500?

 

If the PHY port/ports will not inherit the SVI value changed, the best way is always to have SVI and PHY port/ports with the same MTU value, isn't it?

 

But if the PHY port/ports is/are a dot1Q trunk, all SVI on the trunk should have the same MTU  configured as the PHY ports/ports, also if not needed otherwise potential drops can be caused by frames with DF bit set in SVI interface that have MTU value lesser than the PHY value, correct?

 

Thanks a lot for your suggestion

Omar

1 ACCEPTED SOLUTION

Accepted Solutions
Reza Sharifi
Hall of Fame Expert

Hi Omar,

I have never used Sup-6T before but it works like any other platform you want the physical interface to have jumbo MTU to match.  So, for example; if you have storage connected say to ports 4 and 5 on a blade, you want to enable the mtu on the physical ports for L2 traffic between these ports. On the other hand if the storage is in one vlan (ports 4 and 5) and say a host is in a different vlan (layer-3) than in addition to the physical ports you also need to enable it on the SVI for each vlan because the traffic will be routed from one vlan to another.

HTH

View solution in original post

2 REPLIES 2
Reza Sharifi
Hall of Fame Expert

Hi Omar,

I have never used Sup-6T before but it works like any other platform you want the physical interface to have jumbo MTU to match.  So, for example; if you have storage connected say to ports 4 and 5 on a blade, you want to enable the mtu on the physical ports for L2 traffic between these ports. On the other hand if the storage is in one vlan (ports 4 and 5) and say a host is in a different vlan (layer-3) than in addition to the physical ports you also need to enable it on the SVI for each vlan because the traffic will be routed from one vlan to another.

HTH

View solution in original post

Hella Reza,

 

Thanks a lot for the explanation and confirmation... as I've supposed :-)

 

BR

Omar