Tag: ethernet

Jumbo frames on Cisco

For IOS:

3750(config)# system mtu jumbo 9000
3750(config)# exit
3750# reload

7609(config)#int gigabitEthernet 1/1
7609(config-if)#mtu ?
<1500-9216> MTU size in bytes

7609(config-if)#mtu 9216

Verify in Native IOS:

7609#show interfaces gigabitEthernet 1/1
GigabitEthernet1/1 is up, line protocol is up (connected)
Hardware is C6k 1000Mb 802.3, address is 0007.0d0e.640a (bia 0007.0d0e.640a)
MTU 9216 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255

For CatOS:

Cat6509> (enable) set port jumbo
Usage: set port jumbo <mod/port> <enable|disable>
Cat6509> (enable) set port jumbo 1/1 enable
Jumbo frames enabled on port 1/1.
Cat6509> (enable) 2002 May 29 12:34:35 %PAGP-5-PORTFROMSTP:
Port 1/1 left bridge port 1/1
2002 May 29 12:34:38 %PAGP-5-PORTTOSTP:Port 1/1 joined bridge port 1/1

Verify in CatOS

Cat6509> (enable) show port jumbo
Jumbo frames MTU size is 9216 bytes.
Jumbo frames enabled on port(s) 1/1,9/1.

Literature:
Cisco manual

Jumbo frames on Solaris

For e1000g (Solaris):
Change /kernel/drv/e1000g.conf to:

MaxFrameSize=3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3;
# 0 is for normal ethernet frames.
# 1 is for upto 4k size frames.
# 2 is for upto 8k size frames.
# 3 is for upto 16k size frames.
# These are maximum frame limits, not the actual ethernet frame
# size. Your actual ethernet frame size would be determined by
# protocol stack configuration (please refer to ndd command man pages)
# For Jumbo Frame Support (9k ethernet packet)
# use 3 (upto 16k size frames)

For rge (Solaris):
Maximum MTU supported by rge is 7000.
Change /kernel/drv/rge.conf to:

default_mtu = 7000;

Then reboot.

The result:

xeon# ifconfig -a
. . .
e1000g1: flags=201000843 mtu 9000 index 2
inet 10.0.10.1 netmask ffffff00 broadcast 10.0.10.255
ether 0:18:f3:ef:2a:d1