Subinterface question
ihegyvari
Registered Users Posts: 1 ■□□□□□□□□□
in CCNA & CCENT
Hey Guys,
I'm new here, studying for CCNA and during my labs I wanted to implement a certain design for switch redundancy and I stumbled upon a problem I'm not sure how to fix. So my question is basically lets say you have two layer 2 switched and one router. 1 Switch connects to fas0/0 on the router the other one fas0/1. I have 5 subinterfaces under fas0/1 acting as defualt gateway for the different Vlans I have. Now the problem is that if for any reason the cable connecting switch 1 to fas0/1 goes down so do all the subinterfaces go with it. Is there a way to connect the two fastethernet interfaces on the router...like tie them together in a way that the subinterfaces belong to both not only one, and lets say cable dies connecting fas0/1 and switch 1 but cable is up connecting fas0/0 and switch 2 and because of that subinterfaces stay up and routing continues after spanning tree updates?
Hope I didn't make it too confusing.
Router is a 2811 and this is in Packet Tracer
I'm new here, studying for CCNA and during my labs I wanted to implement a certain design for switch redundancy and I stumbled upon a problem I'm not sure how to fix. So my question is basically lets say you have two layer 2 switched and one router. 1 Switch connects to fas0/0 on the router the other one fas0/1. I have 5 subinterfaces under fas0/1 acting as defualt gateway for the different Vlans I have. Now the problem is that if for any reason the cable connecting switch 1 to fas0/1 goes down so do all the subinterfaces go with it. Is there a way to connect the two fastethernet interfaces on the router...like tie them together in a way that the subinterfaces belong to both not only one, and lets say cable dies connecting fas0/1 and switch 1 but cable is up connecting fas0/0 and switch 2 and because of that subinterfaces stay up and routing continues after spanning tree updates?
Hope I didn't make it too confusing.
Router is a 2811 and this is in Packet Tracer
Comments
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FrankGuthrie
Member Posts: 245
I think FHRP protocols (HSRP, VRRP, or GLBP) need to used here. With the current setup it is not possible.
You have an option, but this is not dynamic. You can make 5 sub-interfaces on Fa0/0 and create those same VLAN's on the other switch. For the IP address on the redudant subinterfaces (fa0/0.1, fa0/0.2, fa0/0.3 etc..) use .2 as the gateway. But this means you need to switch over the gateway on the end host when the link to Fa0/1 fails. I would however not recommend this. -
PCSPreston
Users Awaiting Email Confirmation Posts: 127
If you have fa0/0 then you have sub int of fa0/0.1, 0.2 and so on. I the cable fails then they all go down. You can't have another interface for those sub interfaces to fail over to if I'm not mistaken. -
theodoxa
Member Posts: 1,340 ■■■■□□□□□□
If you had a Layer 3 Switch, you could place two ports on different subnets and connect them to the same router or even to multiple routers. Plus, you could route between the VLANs on the switch itself.R&S: CCENT → CCNA → CCNP → CCIE [ ]
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Virtualization: VCA-DCV [ ] -
elderkai
Member Posts: 279
Configure Fa0/1 how you like, but on the physical(non-subinterface) interface put the "backup-interface fa0/0" command. Then configure the subinterfaces exactly the same on the other one and interconnect the two switches.