Extreme Networks ExtremeWare XOS Guide Manual page 376

IP Unicast Routing
Multicast Routing Protocols
For Protocol-Independent Multicast (PIM), the following behavior changes should be noted in a
multinetting environment:
PIM does not peer with any other PIM router on a secondary subnet.
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PIM also processes data packets from the host on secondary subnets.
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PIM also accepts membership information from hosts on secondary subnets.
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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 Dynamic Host Configuration Protocol (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 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 virtual IP address
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10.0.0.1/24, and the other VRID will have the virtual 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 virtual IP address as
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10.0.0.1/24, and the other VRID will have the virtual IP address as 20.0.0.1/24
ExtremeWare XOS 11.1 Concepts Guide
376