5308xl VLAN Routing

[Y Jeff]

Hi All,

Can someone please recommend the best-practice setting for routing in my scenario? I have one 5308xl as my core switch. My default VLAN (192.168.1.0, vlan IP is 192.168.1.15) has all my servers, several users, and my Cisco frame (WAN) router (192.168.1.1) hanging off of it. The frame router is on an Untagged port on vlan1. In fact, all ports are untagged on both vlans. There are seven different subnets in the frame cloud behind the Cisco router. I also have 'VLAN 2' (10.100.0.0, vlan ip 10.100.1.1) on that core 5308xl which supports users in another building.

My main concern is the default routes. The vlan2 users are getting a dhcp-supplied gateway of 10.100.1.1. The default GW of the switch itself is 192.168.1.1 (my Frame router that has static routes for the entire WAN). I suspect I may have something awry because the vlan2 clients have a lot of who-has broadcasts and other traffic that indicates they may not know where to go.

Any ideas/suggestions would be most welcome.

Thanks!
Jeff

[Y Jeff]

Some add'l info: my frame router (192.168.1.1) serves as the default gw for all devices on the vlan1, and there is a static route on it that points 10.100.0.0 traffic (vlan2) to the switch's IP address (192.168.1.15)......

[Mohieddin Kharnoub · Accepted solution]

Hi

I can understand from your scenario that you have 2 Vlans, and one exit to WAN, that is the Cisco device located in Vlan1, and has a route back to Vlan2 pointing to Vlan1 IP on the 5300.

Also i can understand that you have enabled IP routing on the 5300, and so you have 2 routers connected to each other and functioning properly.

If that is true, and if we can say that your 5300 is considerably the Core of your network then:
You have a proper design, and i can tell you that ARP requests in a medium to big environment are the most interesting traffic that you can see, especially if you have Servers.

So if we can imagine that you have 50 to 100 users on your LAN, and all are talking to the Servers frequently, so the ARP is one of the most traffic you will see.

If you have huge ARP requests in your network that consumes the bandwidth, then you should investigate about it.

With the 5300, you can monitor a whole Vlan to a mirror port, and see who is originating these ARP requests, then do some actions.

Note: one of the common security attacks uses ARP.

Good Luck !!!

[Y Jeff]

Thanks for the input - I am glad that it sounds like I have the proper design. I will look more into all the ARPs; at least it does not appear to be a routing issue.

Thanks!
Jeff