How many IP addresses are allowed on a vlan interface?
How many IP addresses are allowed on a loopback interface?
How can I verify if multiple IP addresses have been configured on a vlan interface?
Environment : This article applies to all Aruba mobility switches and code versions.
Aruba OS supports any number of secondary IP addresses on a vlan or a loopback interface.
Notes:
1. There can be only one Primary IP address.
2. OSPF will NOT form adjacency over secondary IP address.
3. We can also assign Secondary IP addresses to loopback interfaces.
4. Two IP addresses from the same vlan cannot be assigned.
Config:
(ArubaS2500-24P) (vlan "1") #interface vlan 1
(ArubaS2500-24P) (vlan "1") #ip address 10.1.1.1 255.255.255.0
(ArubaS2500-24P) (vlan "1") #ip address 10.1.2.1 255.255.255.0 secondary
(ArubaS2500-24P) (vlan "1") #ip address 10.1.3.1 255.255.255.0 secondary
(ArubaS2500-24P) (vlan "1") #exit
Verify:
(ArubaS2500-24P) (config) #show interface vlan 1
VLAN1 is administratively Up, Line protocol is Up
Hardware is CPU Interface, Address is 00:1a:1e:09:19:40
Description: 802.1Q VLAN
Internet address is 10.1.1.1, Netmask is 255.255.255.0
Internet address is 10.1.2.1, Netmask is 255.255.255.0 secondary
Internet address is 10.1.3.1, Netmask is 255.255.255.0 secondary
IPV6 link-local address is fe80::1a:1e00:109:1940
Global Unicast address(es):
Routing interface is enabled, Forwarding mode is enabled
Directed broadcast is disabled, BCMC Optimization disabled
Encapsulation 802, Loopback not set
Interface index: 50331649
MTU 1500 bytes
Please note that the command " show ip interface vlan 1" will NOT show the secondary interfaces:
(ArubaS2500-24P) (config) #show ip interface vlan 1
vlan 1 is Up, protocol is Up
Internet address is 10.1.1.1/255.255.255.0
Address is statically configured
MTU is 1500
However, show IP interface brief command will show all the IP addresses:
(ArubaS2500-24P) (config) #show ip interface brief
Flags: S - Secondary IP address
Interface IP Address / IP Netmask Admin Protocol Flags
vlan 1 10.1.1.1 / 255.255.255.0 Up Up
vlan 1 10.1.2.1 / 255.255.255.0 Up Up S
vlan 1 10.1.3.1 / 255.255.255.0 Up Up S
mgmt unassigned / unassigned Up Down