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Aruba ACSA study materials
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Aruba ACSA: IP Routing Fundamentals and Layer 3 Services

Aruba ACSA · Work through your exam, one topic at a time.

All guide sections

IP Routing Fundamentals and Layer 3 Services

What you must understand

Aruba switches route when an SVI (VLAN interface) has an IP and ip routing is enabled. Core topics: static routes, connected routes, default gateway, and dynamic protocols - OSPF, BGP, and on CX OSPFv3/BGP for IPv6. Know administrative distance (connected 0, static 1, OSPF 110, BGP 20/200) and longest-prefix-match forwarding.

Layer 3 services: DHCP relay (helper address on the SVI), DHCP server (CX can act as one), VRRP for first-hop redundancy, NTP, DNS, and ARP behavior. Also VRF on CX for routing-table separation.

Traps

  • ip routing must be enabled - an SVI with an IP won't route without it.
  • DHCP relay needs the helper configured on the client-facing SVI, not the server-facing one.
  • Static route with a next-hop that isn't reachable is not installed.
  • Administrative distance decides between protocols; longest prefix decides within the table.

Worked example

Clients in VLAN 10 (10.10.10.0/24) need DHCP from a server at 10.20.20.5. Configure the VLAN 10 SVI with ip helper-address 10.20.20.5. The relay forwards the broadcast as unicast to the server, which replies via the SVI. Without the helper, the DHCP DISCOVER never leaves the subnet.