Netgear XCM8806 Chassis User Manual - Page 624

IGMP Snooping and IGMP, Multicast Routing Protocols, DHCP Server

Page 624 highlights

NETGEAR 8800 User Manual • Direct routes corresponding to secondary interfaces can be exported into the BGP domain (by enabling export of direct routes). IGMP Snooping and IGMP Internet Group Management Protocol (IGMP) snooping and IGMP treat the VLAN as an interface. Only control packets with a source address belonging to the IP networks configured on that interface are accepted. IGMP accepts membership information that originates from hosts in both the primary and secondary subnets. The following describes the changes in behavior of IGMP in an IP multinetting environment: • A Layer 3 VLAN always uses the primary IP address as the source address to send out an IGMP query, and querier election is based on the primary IP address of interface. Because the RFC dictates that there is only one querier per physical segment, the querier may be attached to any of configured IP interfaces, including secondary interfaces, although this is not a recommended configuration. • For a static IGMP group, the membership report is also sent out using the primary IP address. • For local multicast groups such as 224.0.0.X, the membership report is sent out using the first IP address configured on the interface, which is the primary IP address in XCM8800. • The source IP address check is disabled for any IGMP control packets (such as IGMP query and IGMP membership report). Source IP address checking for IGMP control packet is disabled for all VLANs, not just the multinetted VLANs. 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. • PIM also processes data packets from the hosts secondary subnets. • PIM also accepts membership information from hosts on secondary subnets. STP Control protocols like 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 XCM8800 only supports address allocation on the primary IP interface of the configured VLAN. That is, all DHCP clients residing on a bridging domain have IP addresses belonging to the primary subnet. To add a host on secondary subnet, you must manually configure the IP address information on that host. 624 | Chapter 20. IPv4 Unicast Routing

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|
Chapter 20.
IPv4 Unicast Routing
NETGEAR 8800 User Manual
Direct routes corresponding to secondary interfaces can be exported into the BGP
domain (by enabling export of direct routes).
IGMP Snooping and IGMP
Internet Group Management Protocol (IGMP) snooping and IGMP treat the VLAN as an
interface.
Only control packets with a source address belonging to the IP networks configured on that
interface are accepted. IGMP accepts membership information that originates from hosts in
both the primary and secondary subnets. The following describes the changes in behavior of
IGMP in an IP multinetting environment:
A Layer 3 VLAN always uses the primary IP address as the source address to send out
an IGMP query, and querier election is based on the primary IP address of interface.
Because the RFC dictates that there is only one querier per physical segment, the querier
may be attached to any of configured IP interfaces, including secondary interfaces,
although this is not a recommended configuration.
For a static IGMP group, the membership report is also sent out using the primary IP
address.
For local multicast groups such as 224.0.0.X, the membership report is sent out using the
first IP address configured on the interface, which is the primary IP address in XCM8800.
The source IP address check is disabled for any IGMP control packets (such as IGMP
query and IGMP membership report). Source IP address checking for IGMP control
packet is disabled for
all
VLANs, not just the multinetted VLANs.
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.
PIM also processes data packets from the hosts secondary subnets.
PIM also accepts membership information from hosts on secondary subnets.
STP
Control protocols like 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 XCM8800 only
supports address allocation on the primary IP interface of the configured VLAN. That is, all
DHCP clients residing on a bridging domain have IP addresses belonging to the primary
subnet. To add a host on secondary subnet, you must manually configure the IP address
information on that host.