Inter VLAN on multiple L3 switches

[JATINDER KUMAR]

Dear Friends

I have multi L3 switches in my network and i would like to perform intervlan routing on these switches only. I understand well how to perform this using one switch solely as gateway and other switches as L2 and perform routing  but my concern is what is this switch goes down all the network will be down.

So how can i do the redundancy in this case how can i use my another switch also so that if switch one is down swtich two can still do interVLAN and also send the traffic to router for internet or other external networks. please advise

for example:

VLAN 10 : 172.20.10.0/24 Gateway 172.20.10.254 Host 172.20.10.253

VLAN 100 : 172.20.100.0/24 Gateway 172.20.100.254 Host 172.20.100.253

I configured both VLAN assigned ports to the hosts for their respective VLAN. gave ip routing and then configured route also to send external to router. so this is fine.

now comes second router and i am not sure what IPs to give to VLANs of second L3 switch and how it will work if switch one fails. Please guide frnds.

I checked this link but i am not sure if i understood the concept well and this can provide me 100% redundancy.

http://networkengineering.stackexchange.com/questions/17969/intervlan-routing-using-two-layer-3-switches-in-packet-tracer

[Mark Malone]

hey you could give each switch a vlan interface say vlan 10 as an example and then give switch 1 ip 10.1.1.1 switch 2 as 10.1.1.2 and then use HSRP for redundancy, each switch has same routing but only 1 is active at a time

interface vlan 10
ip address 10.1.1.1 255.255.255.0
standby 1 ip 10.1.1.3
standby 1 priority 200
standby 1 preempt

interface vlan 10
ip address 10.1.1.2 255.255.255.0
standby 1 ip 10.1.1.3
standby 1 priority 120
standby 1 preempt

http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750xscg/swhsrp.html

[Jon Marshall]

Depending on the model of your switches you may be able to stack them in which case you do not need to configure the other switch with SVIs ("int vlan x") as the stack shares the configuration.

However the other common way of doing it is to connect your L3 switches together using a trunk link and then using HSRP for the end clients.

HSRP allows both switches to share a virtual IP (VIP) and one switch will be active for that VIP. The end clients use the VIP as their default gateway and if the active switch for the VIP fails then the other switch takes over the VIP and this is transparent to the end clients.

HSRP is very common, alternatives being VRRP and GLBP which you could also consider.

Which to use really depends on your topology.

If you do a search for your switch model and HSRP you should get the configuration guide which will show you how to set it up.

Jon