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dhcp-snooping trusted servers

dhcp-snooping trusted servers

David_Rickard
New Contributor
Hi all,

I am just looking at using extreme as edge switches, have been using them for core and aggregation for years. We have a large network with two central DHCP servers which we then use UDP forwarding from each user vlan.

As I see it, we need to enable dhcp snooping on all ports of the switch including the uplinks so they see the server packets on the uplinks as well as the client packets on the edge ports. This will discard server packets on all ports by default so we either need to set the uplinks as trusted ports or use the trusted server feature.

The trusted server commend is better because it will guard against rogue packets on the uplinks too, but there is a limit of 8 and if we have four user vlans on a switch, we would need to issue two trusted server commands for each of the central servers on each vlan (eight commands) PLUS one per VLAN for the local gateway relay address so we will easily run out of trusted servers.

Is this right? How do people get round this, or do you just use the trusted port commands for large networks?

Also, I have read somewhere you can't put snooping on LAG ports, as all our uplinks are LAGged does this mean the feature is completely useless to us anyway?
15 REPLIES 15

dflouret
Extreme Employee
David,

Have you checked the bootprelay command?

You can enable it globally for a virtual router and all its vlans
enable bootprelay vr vr-defaultor only for specific vlans
enable bootprelay vlan test
You can also add one or more DHCP servers globally to the virtual router for all vlans to use
configure bootprelay add 10.1.0.1or configure specific DHCP servers for individual vlans
configure bootprelay vlan test add 10.2.0.2

GTM-P2G8KFN