LevelOne GTL-2691 - Manual (Page 77)

C HAPTER 1 | Introduction
Description of Software Features
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E THERNET R ING
P ROTECTION
S WITCHING
ERPS can also be used to increase the availability and robustness of
Ethernet rings, such as those used in Metropolitan Area Networks (MAN).
ERPS technology converges in a little over 50 ms. ERPS supports up to 255
nodes in the ring structure. And the convergence time is also independent
of the number of nodes in the ring.
IP R OUTING
The switch provides Layer 3 IP routing. To maintain a high rate of
throughput, the switch forwards all traffic passing within the same
segment, and routes only traffic that passes between different
subnetworks. The wire-speed routing provided by this switch lets you
easily link network segments or VLANs together without having to deal
with the bottlenecks or configuration hassles normally associated with
conventional routers.
Routing for unicast traffic is supported with static routing, Routing
Information Protocol (RIP), Open Shortest Path First (OSPF) protocol.
Static Routing – Traffic is automatically routed between any IP interfaces
configured on the switch. Routing to statically configured hosts or subnet
addresses is provided based on next-hop entries specified in the static
routing table.
RIP – This protocol uses a distance-vector approach to routing. Routes are
determined on the basis of minimizing the distance vector, or hop count,
which serves as a rough estimate of transmission cost.
OSPF – This approach uses a link state routing protocol to generate a
shortest-path tree, then builds up its routing table based on this tree. OSPF
produces a more stable network because the participating routers act on
network changes predictably and simultaneously, converging on the best
route more quickly than RIP. OSPFv2 is provided for routing IPv4 traffic,
and OSPFv3 for routing IPv6 traffic.
E QUAL - COST
M ULTIPATH L OAD
B ALANCING
When multiple paths to the same destination and with the same path cost
are found in the routing table, the Equal-cost Multipath (ECMP) algorithm
first checks if the cost is lower than that of any other routing entries. If the
cost is the lowest in the table, the switch will use up to eight paths having
the lowest path cost to balance traffic forwarded to the destination. ECMP
uses either equal-cost unicast multipaths manually configured in the static
routing table, or equal-cost multipaths dynamically detected by the Open
Shortest Path Algorithm (OSPF). In other words, it uses either static or
OSPF entries, not both.
R OUTER R EDUNDANCY
The Virtual Router Redundancy Protocol (VRRP) uses a virtual IP address to
support a primary router and multiple backup routers. The backups can be
configured to take over the workload if the master fails or to load share the
traffic. The primary goal of this protocol is to allow a host device which has
been configured with a fixed gateway to maintain network connectivity in
case the primary gateway goes down.