Users Guide

11–Marvell Teaming Services
Executive Summary
152 BC0054508-00 M
The reason is that ARP is not a routable protocol. It does not have an IP header
and therefore, is not sent to the router or default gateway. ARP is only a local
subnet protocol. In addition, because the G-ARP is not a broadcast packet, the
router will not process it and will not update its own ARP cache.
The only way that the router would process an ARP that is intended for another
network device is if it has Proxy ARP enabled and the host has no default
gateway. This situation is very rare and not recommended for most applications.
Transmit traffic through a router is load balanced because transmit load balancing
is based on the source and destination IP address and TCP/UDP port number.
Because routers do not alter the source and destination IP address, the load
balancing algorithm works as intended.
Configuring routers for hot standby routing protocol (HSRP) does not allow for
receive load balancing to occur in the adapter team. In general, HSRP allows for
two routers to act as one router, advertising a virtual IP and virtual MAC address.
One physical router is the active interface while the other is standby. Although
HSRP can also load share nodes (using different default gateways on the host
nodes) across multiple routers in HSRP groups, it always points to the primary
MAC address of the team.
Generic Trunking
Generic Trunking is a switch-assisted teaming mode and requires configuring
ports at both ends of the link: server interfaces and switch ports. This port
configuration is often referred to as Cisco Fast EtherChannel or Gigabit
EtherChannel. In addition, generic trunking supports similar implementations by
other switch OEMs such as Extreme Networks Load Sharing and Bay Networks or
IEEE 802.3ad Link Aggregation static mode. In this mode, the team advertises
one MAC Address and one IP Address when the protocol stack responds to ARP
Requests. In addition, each physical adapter in the team uses the same team
MAC address when transmitting frames. Use of the address is possible because
the switch at the other end of the link is aware of the teaming mode and will
handle the use of a single MAC address by every port in the team. The forwarding
table in the switch will reflect the trunk as a single virtual port.
In this teaming mode, the intermediate driver controls load balancing and failover
for outgoing traffic only, while incoming traffic is controlled by the switch firmware
and hardware. As is the case for Smart Load Balancing, the QLASP intermediate
driver uses the IP/TCP and UDP source and destination addresses to load
balance the transmit traffic from the server. Most switches implement an XOR
hashing of the source and destination MAC address.
NOTE
Generic trunking is not supported on iSCSI offload adapters.