Blue Arc Titan SiliconServer, Руководство системного администратора

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Network Configuration
74 Titan SiliconServer
consists of a destination network ID, a gateway address, and sometimes a subnet mask. The
entries in the table are persistent. If the server is restarted, the table preserves the static routing
entries.
Titan supports both network and host-based static routes. Select the Network option to set up
a route to address all the computers on a specific network. Select the Host option to address a
specific computer that is on a different network than the router through which it is normally
addressed. The maximum possible static routes is 128. Note that default gateways also count
against the total number of static routes.
Default Gateways
Titan supports multiple default gateways for routing IP communication. When connected to
multiple IP networks, add a default gateway for each network to which the Titan is connected.
When configured in this way, Titan will direct traffic through the appropriate default gateway by
matching the source IP address specified in outgoing packets with the gateway on the same
subnet.
With multiple default gateways, Titan routes IP traffic logically and reduces the need to specify
static routes for every network with which Titan needs to communicate.
Dynamic Host Routes
Titan also supports ICMP redirects , an industry standard which provides a means for routers to
convey routing information back to the server. When one router detects that another router
offers a better route to a destination, it sends a redirect that temporarily overrides the system’s
routing table. Being router-based, dynamic redirects do not require any configuration, but they
can be viewed in the routing table.
Titan stores dynamic host routes in its route cache for ten minutes. When the time has elapsed,
packets to the selected destination use the route specified in the routing table until the server
receives another ICMP redirect.
Titan’s route cache can store a maximum of 65,000 dynamic routes at a time.
Routing Precedence
Titan's routing options follow an order where the most specific route available for the outgoing
IP packet will be chosen. The host route is the most specific since it targets a specific computer
on the network. The network route is the next most specific since it targets a specific network. A
gateway is the least specific route and hence the third routing option for Titan.
Therefore, if Titan finds a host route for the outgoing IP packet, it will choose that route over a
network route or gateway. Similarly, when a host route is not available, Titan will choose a
corresponding network route or, in the absence of host and network routes, Titan will send the
packet to a default gateway.