Cisco Catalyst 2960 and Cisco Catalyst 3750 MTU (Jumbo Frame) Testing

C2960#sh ver | in IOS|Compile
Cisco IOS Software, C2960 Software (C2960-LANBASEK9-M), Version 12.2(55)SE1, RELEASE SOFTWARE (fc1)
Compiled Thu 02-Dec-10 08:16 by prod_rel_team
C2960#
C2960#sh ver | in Model number
Model number                    : WS-C2960G-24TC-L
C2960#
C2960#sh system mtu

System MTU size is 1500 bytes
System Jumbo MTU size is 1500 bytes
System Alternate MTU size is 1500 bytes
Routing MTU size is 1500 bytes
C2960#
C2960#sh cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
                  D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
C3750            Gig 0/21          159              S I   WS-C3750- Gig 1/0/1
C2960#
C2960#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
C2960(config)#system mtu ?
  <1500-1998>  MTU size in bytes
  jumbo        Set Jumbo MTU value for GigabitEthernet or TenGigabitEthernet
               interfaces
  routing      Set the Routing MTU for the system

C2960(config)#system mtu 1998
Changes to the system MTU will not take effect until the next reload is done
C2960(config)#
C2960(config)#do sh system mtu

System MTU size is 1500 bytes
On next reload, System MTU will be 1998 bytes
System Jumbo MTU size is 1500 bytes
System Alternate MTU size is 1500 bytes
Routing MTU size is 1500 bytes
C2960(config)#
C2960(config)#system mtu jumbo ?
  <1500-9000>  Jumbo MTU size in bytes

C2960(config)#system mtu jumbo 9000
Changes to the system jumbo MTU will not take effect until the next reload is done
C2960(config)#
C2960(config)#do sh system mtu

System MTU size is 1500 bytes
On next reload, System MTU will be 1998 bytes
System Jumbo MTU size is 1500 bytes
On next reload, System Jumbo MTU will be 9000 bytes
System Alternate MTU size is 1500 bytes
Routing MTU size is 1500 bytes
C2960(config)#
C2960(config)#end
C2960#
C2960#reload

System configuration has been modified. Save? [yes/no]: no
Proceed with reload? [confirm]

--- output omitted ---
================================================================================
C3750#sh ver | in IOS|Compile
Cisco IOS Software, C3750 Software (C3750-IPSERVICESK9-M), Version 12.2(55)SE1, RELEASE SOFTWARE (fc1)
Compiled Thu 02-Dec-10 07:46 by prod_rel_team
C3750#
C3750#sh ver | in Model number
Model number                    : WS-C3750-24TS-S
C3750#
C3750#sh system mtu

System MTU size is 1500 bytes
System Jumbo MTU size is 1500 bytes
System Alternate MTU size is 1500 bytes
Routing MTU size is 1500 bytes
C3750#
C3750#sh cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
                  D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
C2960            Gig 1/0/1         154              S I   WS-C2960G Gig 0/21
C3750#
C3750#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
C3750(config)#system mtu ?
  <1500-1998>  MTU size in bytes
  jumbo        Set Jumbo MTU value for GigabitEthernet or TenGigabitEthernet
               interfaces
  routing      Set the Routing MTU for the system

C3750(config)#system mtu 1998
Changes to the system MTU will not take effect until the next reload is done
C3750(config)#
C3750(config)#do sh system mtu

System MTU size is 1500 bytes
On next reload, System MTU will be 1998 bytes
System Jumbo MTU size is 1500 bytes
System Alternate MTU size is 1500 bytes
Routing MTU size is 1500 bytes
C3750(config)#
C3750(config)#system mtu jumbo ?
  <1500-9000>  Jumbo MTU size in bytes

C3750(config)#system mtu jumbo 9000
Changes to the system jumbo MTU will not take effect until the next reload is done
C3750(config)#
C3750(config)#do sh system mtu

System MTU size is 1500 bytes
On next reload, System MTU will be 1998 bytes
System Jumbo MTU size is 1500 bytes
On next reload, System Jumbo MTU will be 9000 bytes
System Alternate MTU size is 1500 bytes
Routing MTU size is 1500 bytes
C3750(config)#
C3750(config)#end
C3750#
C3750#reload

System configuration has been modified. Save? [yes/no]: no
Proceed with reload? [confirm]

--- output omitted ---
================================================================================
C2960#sh system mtu

System MTU size is 1998 bytes
System Jumbo MTU size is 9000 bytes
System Alternate MTU size is 1998 bytes
Routing MTU size is 1500 bytes
C2960#
C2960#sh run | in mtu
system mtu routing 1500
C2960#
C2960#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
C2960(config)#no system mtu routing
C2960(config)#end
C2960#
C2960#sh system mtu

System MTU size is 1998 bytes
System Jumbo MTU size is 9000 bytes
System Alternate MTU size is 1998 bytes
Routing MTU size is 1998 bytes
C2960#
C2960#sh run | in mtu
system mtu routing 1998
C2960#
================================================================================
C3750#sh system mtu

System MTU size is 1998 bytes
System Jumbo MTU size is 9000 bytes
System Alternate MTU size is 1998 bytes
Routing MTU size is 1500 bytes
C3750#
C3750#sh run | in mtu
system mtu routing 1500
C3750#
C3750#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
C3750(config)#no system mtu routing
C3750(config)#end
C3750#
C3750#sh system mtu

System MTU size is 1998 bytes
System Jumbo MTU size is 9000 bytes
System Alternate MTU size is 1998 bytes
Routing MTU size is 1998 bytes
C3750#
C3750#sh run | in mtu
system mtu routing 1998
C3750#
================================================================================
C2960#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
C2960(config)#int vlan 1
C2960(config-if)#ip add 1.1.1.1 255.255.255.0
C2960(config-if)#no shut
C2960(config-if)#end
C2960#
00:08:40.026: %LINK-3-UPDOWN: Interface Vlan1, changed state to up
00:08:40.034: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up
C2960#
================================================================================
C3750#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
C3750(config)#int vlan 1
C3750(config-if)#ip add 1.1.1.2 255.255.255.0
C3750(config-if)#no shut
C3750(config-if)#end
C3750#
00:03:20.621: %LINK-3-UPDOWN: Interface Vlan1, changed state to up
00:03:20.831: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan1, changed state to up
C3750#
================================================================================
C2960#ping 1.1.1.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.2, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/11/34 ms
C2960#
C2960#ping 1.1.1.2 size 1998 df

Type escape sequence to abort.
Sending 5, 1998-byte ICMP Echos to 1.1.1.2, timeout is 2 seconds:
Packet sent with the DF bit set
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/5/9 ms
C2960#
C2960#ping 1.1.1.2 size 1999 df

Type escape sequence to abort.
Sending 5, 1999-byte ICMP Echos to 1.1.1.2, timeout is 2 seconds:
Packet sent with the DF bit set
.....
Success rate is 0 percent (0/5)
C2960#
C2960#ping 1.1.1.2 size 1999

Type escape sequence to abort.
Sending 5, 1999-byte ICMP Echos to 1.1.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/5/9 ms
C2960#