2: Product Overview
XPress-Pro SW 94000 User Guide 15
Intra-VLAN Communication
The Xpress-Pro SW 94000 switch supports intra-VLAN communication through
hardware, as described in “Basic Functions” section.
Inter-VLAN Communication
The Xpress-Pro SW 94000 switch supports inter-VLAN communication using CPU-based
routing software
GVRP In addition to network management tools that allow network administrators to statically
add and delete VLAN member ports, the routing switch supports GARP VLAN
Registration Protocol (GVRP). GVRP supports dynamic registration of VLAN port
members within a switch and across multiple switches.
In addition to dynamically updating registration entries within a switch, GVRP is used to
communicate VLAN registration information to other VLAN-aware switches, so that
members of a VLAN can cover a wide span of switches on a network.
GVRP allows both VLAN-aware workstations and switches to issue and revoke VLAN
memberships. VLAN-aware switches register and propagate VLAN membership to all
ports that are part of the active topology of the VLAN.
IGMP Snooping and IP Multicast Filtering The Internet Group Management Protocol (IGMP) runs between hosts and their
immediately neighboring multicast routers. The protocol’s mechanisms allow a host to
inform its local router that it wants to receive transmissions addressed to a specific
multicast group.
Routers periodically query the LAN to determine if known group members are still active.
If there is more than one router on the LAN performing IP multicasting, one of the routers
is elected “querier” and assumes the responsibility of querying the LAN for group
members.
Based on the group membership information learned from the IGMP, a router can
determine which (if any) multicast traffic needs to be forwarded to each of its “leaf” sub-
networks. Multicast routers use this information, along with a multicast routing protocol, to
support IP multicasting across the Internet.
IGMP provides the final step in an IP multicast packet delivery service since it is only
concerned with the forwarding of multicast traffic from the local route to group members
on directly attached sub-networks.
Routing switches support IP Multicast Filtering by:
Passively snooping on the IGMP Query and IGMP Report packets transferred
between IP Multicast Routers and IP Multicast host groups to learn IP Multicast group
members, and
Actively sending IGMP Query messages to solicit IP Multicast group members.