I85PREP
⌘ K
Extreme Data Center (VOSS/VSP) study materials
Extreme Data Center (VOSS/VSP) study resources

Extreme Data Center (VOSS/VSP): IP Routing and Layer 3 Services on VOSS/VSP

Extreme Data Center (VOSS/VSP) · Work through your exam, one topic at a time.

All guide sections

IP Routing and Layer 3 Services on VOSS/VSP

Layer 3 on VOSS/VSP spans two ideas: routing inside one node (interfaces, OSPF/BGP, VRF) and stretching an IP subnet across the fabric with an L3 VSN.

L3 VSN mechanics

  • Create the VLAN, bind an IP interface to it, and map the VLAN to an I-SID. The subnet then exists at every BEB that terminates that I-SID.
  • Both sites use addresses in the same subnet; the I-SID provides L2 forwarding, so ARP resolves across the fabric.
  • For routing between subnets, enable a routing protocol or static routes on the VSP, and confirm global IP routing is on.

Routing features tested

  • OSPF: router ospf to start the process, then per-interface ip ospf enable with an area; neighbours appear in show ip ospf neighbor.
  • BGP: router bgp <asn>, neighbor <ip> remote-as <asn>, plus network statements; verify with show ip bgp summary.
  • VRF: separate routing tables per tenant, with interfaces bound to the VRF.
  • VRRP: ip vrrp address <vrid> <virtual-ip> on the VLAN interface gives a shared gateway, useful where two VSPs serve one site.
  • Redistribution and route policy decide which prefixes leak between protocols or VRFs.

Worked example

Two data centres share subnet 10.10.10.0/24 over I-SID 10100. Site A holds 10.10.10.1/24 on VLAN 300; site B holds 10.10.10.2/24 on VLAN 310 mapped to the same I-SID. Hosts ping with no routing at all, because it is one subnet. A second subnet, 10.20.20.0/24, exists only at B. For A to reach it, OSPF must be enabled on B's 10.20.20.1 interface and on both I-SID interfaces, and show ip route on A must show 10.20.20.0/24 learned from B. Reasoning: the I-SID solves L2 reachability only; prefixes beyond it need a routing protocol.

Traps

Putting an IP address on a VLAN never mapped to an I-SID and expecting fabric-wide reach; starting OSPF but forgetting per-interface ip ospf enable, so no adjacency forms; overlapping subnets at two sites on different I-SIDs; asymmetric routing with VRRP when only one peer is inspected; and MTU problems on routed paths through the fabric.