Networking Blog

Link aggregation between Cisco 3750 switch and Ubintu 9.10
Ubuntu configuration:
Install ifenslave — Attach and detach slave network devices to a bonding device.

apt-get install  ifenslave

Edit or create file /etc/modprobe.d/aliases.conf

alias bond0 bonding
options bonding mode=4 miimon=100

where mode 4 – IEEE 802.3ad Dynamic link aggregation. Creates aggregation groups that share the same speed and
duplex settings. Utilizes all slaves in the active aggregator according to the 802.3ad specification.
Edit /etc/network/interfaces.

auto bond0
iface bond0 inet static
        address 192.168.200.5
        netmask 255.255.255.0
        network 192.168.200.0
        broadcast 192.168.200.255
        post-up ifenslave bond0 eth0 eth1
        gateway 192.168.200.1
        dns-nameservers 192.168.200.1
        dns-search example.com

UPDATE (02.01.2012): Ubuntu 11.10 (oneiric).

1.  Edit or create file /etc/modprobe.d/aliases.conf

alias netdev-bond0 bonding
options bonding mode=4 miimon=100

or

2. To run bonding first put module “bonding” in “/etc/modules” :

# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
loop
lp
rtc
bonding

In “/etc/network/interfaces”

auto bond0
iface bond0 inet static
        slaves eth0 eth1
        bond_mode 4
        bond_miimon 100
        address 192.168.200.5
        netmask 255.255.255.0
        network 192.168.200.0
        broadcast 192.168.200.255
        post-up ifenslave bond0 eth0 eth1

Cisco configuration ( Gi1/0/1 and Gi1/0/2 will be aggregated ):

cisco-3750(config)#interface range GigabitEthernet 1/0/1, GigabitEthernet 1/0/2
cisco-3750(config-if-range)#switchport trunk encapsulation dot1q
cisco-3750(config-if-range)#switchport trunk allowed vlan 10,20
cisco-3750(config-if-range)#switchport mode trunk
cisco-3750(config-if-range)#channel-group 1 mode active
Creating a port-channel interface Port-channel 1
cisco-3750(config-if-range)#end
cisco-3750#

Configuration of interface Port-Channel 1 must be exactly the same as Gi1/0/1 and Gi1/0/2.

cisco-3750#sh ru int Po1
Building configuration...
Current configuration : 159 bytes
!
interface Port-channel1
 switchport trunk encapsulation dot1q
 switchport trunk allowed vlan 10,20
end

If you want to modify configuration of aggregated interfaces, modify only configuration of Port-Channel interface.
And the last step is to set load-balance algorithm:

cisco-3750(config)#port-channel load-balance src-dst-ip
cisco-3750#sh etherchannel load-balance
EtherChannel Load-Balancing Operational State (src-dst-ip):
Non-IP: Source XOR Destination MAC address
  IPv4: Source XOR Destination IP address
  IPv6: Source XOR Destination IP address

cisco-3750#show etherchannel summary
Flags:  D - down        P - in port-channel
        I - stand-alone s - suspended
        H - Hot-standby (LACP only)
        R - Layer3      S - Layer2
        U - in use      f - failed to allocate aggregator
        u - unsuitable for bundling
        w - waiting to be aggregated
        d - default port

Number of channel-groups in use: 1
Number of aggregators:           1

Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
1      Po1(SU)         LACP      Gi1/0/1(P)  Gi1/0/2(P)

cisco-3750#
cisco-3750#show etherchannel protocol
                Channel-group listing:
                ----------------------
Group: 1
----------
Protocol:  LACP

Traffic on Gi1/0/1

Traffic on Gi1/0/2

Traffic on Port-Channel1