We will used “network.service” daemon, so “NetworkManager.service” must be inoperative to avoid conflicts :

[root@fedora22 ~]# systemctl is-active NetworkManager.service
 inactive

 

[root@fedora22 ~]# systemctl is-enabled NetworkManager.service
 disabled

Logged as “root”, we see those net work interfaces :

[root@fedora22 ~]# ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
 inet 127.0.0.1/8 scope host lo
 valid_lft forever preferred_lft forever
 inet6 ::1/128 scope host
 valid_lft forever preferred_lft forever
2: eno16780032: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
 link/ether 00:0c:29:9e:e3:8d brd ff:ff:ff:ff:ff:ff
 inet 192.168.1.200/24 brd 192.168.1.255 scope global eno16780032
 valid_lft forever preferred_lft forever
 inet6 fe80::20c:29ff:fe9e:e38d/64 scope link
 valid_lft forever preferred_lft forever
3: eno33559296: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
 link/ether 00:0c:29:9e:e3:97 brd ff:ff:ff:ff:ff:ff
 inet6 fe80::20c:29ff:fe9e:e397/64 scope link
 valid_lft forever preferred_lft forever
4: eno33559296.100@eno33559296: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
 link/ether 00:0c:29:9e:e3:97 brd ff:ff:ff:ff:ff:ff
 inet 192.168.2.200/24 brd 192.168.2.255 scope global eno33559296.100
 valid_lft forever preferred_lft forever
 inet6 fe80::20c:29ff:fe9e:e397/64 scope link
 valid_lft forever preferred_lft forever

To enable Jumbo Frame on this VLAN 100 network interface “eno33559296”, just add “MTU=9000” in configuration files :

[root@fedora22 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eno33559296
HWADDR="00:0C:29:9E:E3:97"
DEVICE="eno33559296"
TYPE="Ethernet"
BOOTPROTO="none"
ONBOOT="yes"a
DEFROUTE="no"
MTU="9000"

[root@fedora22 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eno33559296.100
DEVICE=eno33559296.100
BOOTPROTO=static
ONBOOT=yes
IPADDR=192.168.2.200
NETMASK=255.255.255.0
USERCTL=no
NETWORK=192.168.2.0
VLAN=yes
MTU="9000"

Restart the networking service :

[root@fedora22 ~]# systemctl restart network.service

“Jumbo frames” MTU size is now enabled :

[root@fedora22 ~]# ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default
 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eno16780032: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
 link/ether 00:0c:29:9e:e3:8d brd ff:ff:ff:ff:ff:ff
3: eno33559296: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc mq state UP mode DEFAULT group default qlen 1000
 link/ether 00:0c:29:9e:e3:97 brd ff:ff:ff:ff:ff:ff
6: eno33559296.100@eno33559296: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc noqueue state UP mode DEFAULT group default
 link/ether 00:0c:29:9e:e3:97 brd ff:ff:ff:ff:ff:ff

We can verify (using unfragmented ICMP packets) :

[root@fedora22 ~]# ping -v -M do -s 8972 -c2 192.168.2.205
PING 192.168.2.205 (192.168.2.205) 8972(9000) bytes of data.
8980 bytes from 192.168.2.205: icmp_seq=1 ttl=64 time=1.61 ms
8980 bytes from 192.168.2.205: icmp_seq=2 ttl=64 time=0.426 ms
--- 192.168.2.205 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 0.426/1.019/1.613/0.594 ms

A “tpcdump” on the target server shows :

[root@pc57 ~]# tcpdump -vv -i eno33559296.100
tcpdump: listening on eno33559296.100, link-type EN10MB (Ethernet), capture size 262144 bytes
10:03:36.067284 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 9000)
 192.168.2.200 > pc57.home: ICMP echo request, id 1990, seq 1, length 8980
10:03:36.067419 IP (tos 0x0, ttl 64, id 17588, offset 0, flags [none], proto ICMP (1), length 9000)
 pc57.home > 192.168.2.200: ICMP echo reply, id 1990, seq 1, length 8980
10:03:37.068994 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto ICMP (1), length 9000)
 192.168.2.200 > pc57.home: ICMP echo request, id 1990, seq 2, length 8980
10:03:37.069084 IP (tos 0x0, ttl 64, id 18536, offset 0, flags [none], proto ICMP (1), length 9000)
 pc57.home > 192.168.2.200: ICMP echo reply, id 1990, seq 2, length 8980

 

 

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6 thoughts on “fedora22 : enable jumbo frames

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