SVI secondary ip add

[maher.mina (Mina M)]

Hello,
i have a switch L3 who has an SVI with 2 ip add on the same subnet, an example

interface vlan 10
ip add 192.168.1.2 255.255.255.0
ip add 192.168.1.3 255.255.255.0 secondary

Why the use of 2 ip add on the interface. I looked everywhere, i don’t understand why.

Thanks again
Mina

[lagapidis (Lazarus Agapidis)]

Hello Mina

You can add a secondary IP address to any Layer 3 interface on a Cisco device. This can be a physical router interface, an SVI of a Layer 3 switch, or even a subinterface. Some reasons to use a secondary IP address, either in the same subnet or in a different subnet from the primary address, can be found in this post:

IPv6 Solicited Node Multicast Address

Hello Daniel When IPv4 was originally created, each interface, and each host, could only have a single IP address. Later improvements allowed for secondary addresses to be used, which were very useful. For this reason, IPv6 was designed from the beginning to be able to incorporate multiple address assignments. There are many advantages to being able to so easily assign multiple addresses to an interface. Some of these include: The introduction of multiple connections to the Internet with …

I hope this has been helpful!

Laz