Specifications

272 ExtremeWare XOS 11.0 Concepts Guide
IP Unicast Routing
• PIM also accepts membership information from hosts on secondary subnets.
EAPS, ESRP, and STP
Control protocols like Ethernet Automatic Protection Switching (EAPS), Extreme Standby Router
Protocol (ESRP), and the Spanning Tree Protocol (STP) treat the VLAN as an interface. If the protocol
control packets are exchanged as Layer 3 packets, then the source address in the packet is validated
against the IP networks configured on that interface.
DHCP Server
The DHCP server implementation in ExtremeWare XOS 11.0 will only support address allocation on the
primary IP interface of the configured VLAN. That is, all DHCP clients residing on a bridging domain
will have IP address belonging to the primary subnet. To add a host on secondary subnet, you must
manually configure the IP address information on that host.
DHCP Relay
When the switch is configured as a Dynamic Host Configuration Protocol (DHCP) relay agent, it will
forward the DHCP request received from a client to the DHCP server. When doing so, the system sets
the GIADDR field in the DHCP request packet to the primary IP address of the ingress VLAN. This
means that the DHCP server that resides on a remote subnet will allocate an IP address for the client in
the primary subnet range.
VRRP
The Virtual Router Redundancy Protocol (VRRP) protection can be provided for the primary as well as
for the secondary IP addresses of a VLAN. For multinetting, the IP address assigned to an VRRP virtual
router identifier (VRID) can be either the primary or the secondary IP addresses of the corresponding
VLAN.
For example, assume a VLAN v1 with two IP addresses: a primary IP address of 10.0.0.1/24, and a
secondary IP address of 20.0.0.1/24.
To provide VRRP protection to such a VLAN, you must configure one of the following:
• Configure VRRP in VLAN v1 with two VRRP VRIDs. One VRID will have the master IP address
10.0.0.1/24, and the other VRID will have the master IP address 20.0.0.1/24. The other VRRP router,
the one configured to act as backup, should be configured similarly.
—OR—
• Configure VRRP in VLAN v1 with two VRRP VRIDs. One VRID will have the backup IP address as
10.0.0.1/24, and the other VRID will have the backup IP address as 20.0.0.1/24
It is possible for a VRRP VR to have multiple virtual IP addresses assigned to it. In this case, the
following conditions must be met:
• Multiple virtual IP addresses must be on the same subnet.
• Multiple virtual IP addresses must either all be owned by the switch or all not be owned by the
switch.
For example, if you have a VLAN v1 that has IP addresses 1.1.1.1/24 and 2.2.2.2/24, the following
configurations are allowable:
• VRRP VR on v1 with VRID of 99 with virtual IP addresses of 1.1.1.2 and 1.1.1.3
• VRRP VR on v1 with VRID of 99 with virtual IP addresses of 1.1.1.98 and 1.1.1.99