Netgear XCM8810 Chassis User Manual - Page 625

DHCP Relay, Con VRRP in VLAN

Page 625 highlights

NETGEAR 8800 User Manual DHCP Relay When the switch is configured as a DHCP relay agent, it forwards 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 allocates an IP address for the client in the primary subnet range. VRRP 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 should have the virtual IP address 10.0.0.1/24, and the other VRID should 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 should have the virtual IP address as 10.0.0.1/24, and the other VRID should have the virtual IP address as 20.0.0.1/24. It is possible for a VRRP VR to have additional virtual IP addresses assigned to it. In this case, the following conditions must be met: • Multiple virtual IP addresses for the same VRID must be on the same subnet. • Multiple virtual IP addresses must all not be owned by the switch. Assuming a VLAN v1 that has IP addresses 1.1.1.1/24 and 2.2.2.2/24, here are some more examples of valid configurations: • 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 100 with virtual IP addresses of 2.2.2.3 and 2.2.2.4 • VRRP VR on v1 with VRID of 99 with virtual IP addresses of 1.1.1.98 and 1.1.1.99 • VRRP VR on v1 with VRID of 100 with virtual IP addresses of 2.2.2.98 and 2.2.2.99 Given the same VLAN v1 as above, here are some invalid configurations: • VRRP VR on v1 with VRID of 99 with virtual IP addresses of 1.1.1.1 and 2.2.2.2 (the virtual IP addresses are not on the same subnet) • VRRP VR on v1 with VRID of 100 with virtual IP addresses of 2.2.2.2 and 1.1.1.1 (the virtual IP addresses are not on the same subnet) Chapter 20. IPv4 Unicast Routing | 625

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Chapter 20.
IPv4 Unicast Routing
|
625
NETGEAR 8800 User Manual
DHCP Relay
When the switch is configured as a DHCP relay agent, it forwards 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 allocates an IP address for the client in the
primary subnet range.
VRRP
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 should have the virtual IP
address 10.0.0.1/24, and the other VRID should 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 should have the virtual IP
address as 10.0.0.1/24, and the other VRID should have the virtual IP address as
20.0.0.1/24.
It is possible for a VRRP VR to have additional virtual IP addresses assigned to it. In this
case, the following conditions must be met:
Multiple virtual IP addresses for the same VRID must be on the same subnet.
Multiple virtual IP addresses must all not be owned by the switch.
Assuming a VLAN
v1
that has IP addresses 1.1.1.1/24 and 2.2.2.2/24, here are some more
examples of valid configurations:
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 100 with virtual IP addresses of 2.2.2.3 and 2.2.2.4
VRRP VR on
v1
with VRID of 99 with virtual IP addresses of 1.1.1.98 and 1.1.1.99
VRRP VR on
v1
with VRID of 100 with virtual IP addresses of 2.2.2.98 and 2.2.2.99
Given the same VLAN
v1
as above, here are some invalid configurations:
VRRP VR on
v1
with VRID of 99 with virtual IP addresses of 1.1.1.1 and 2.2.2.2 (the
virtual IP addresses are not on the same subnet)
VRRP VR on
v1
with VRID of 100 with virtual IP addresses of 2.2.2.2 and 1.1.1.1 (the
virtual IP addresses are not on the same subnet)