7-3
Using the IP Routing Table Window
Route Mask
Indicates the mask to be logical-ANDed with the destination address before being
compared to the value in the ipRouteDest field, according to the ipRouteMask. For
those systems that do not support arbitrary subnet masks, an agent constructs the
value of the ipRouteMask by determining whether the value of the corresponding
ipRouteDest field belongs to a class-A, B, or C network, and then uses one of the
following:
Mask Network
255.0.0.0 class-A
255.255.0.0 class-B
255.255.255.0 class-C
If the value of the ipRouteDest is 0.0.0.0 (a default route), then the mask value is
also 0.0.0.0. It should be noted that all IP routing subsystems implicitly use this
mechanism. When a host or gateway receives an IP datagram, it must determine
if the datagram’s final destination is on the local network or on another network.
The IP software does not need to examine the entire IP address to make this
local/remote network decision; it only needs to compare the network portion of
the received datagram’s IP address with the network mask. If the datagram is
destined for a host on the local net, the datagram is delivered directly; otherwise,
it is sent to the IP address specified in the “next hop” field of the routing table.
Route Interface
The index value (ipRouteIfIndex) which uniquely identifies the local interface
through which the next hop of this route should be reached. The interface
identified by a particular value of this index is the same interface as identified by
the same value of ifIndex.
Route Protocol
The routing mechanism via which this route was learned. Inclusion of values for
gateway routing protocols is not intended to imply that hosts should support
those protocols, according to the ipRouteProto.
• other (1)—none of the following
• local (2)—non-protocol information, e.g., manually configured entries
• netmgmt (3)—set via a network management protocol
• icmp (4)—obtained via ICMP, e.g., Redirect
•egp (5)
• ggp (6)
• hello (7)
•rip (8)
• is-is (9)
• es-is (10)
• ciscoIgrp (11)
• bbnSpflgp (12)
•ospf (13)
•bgp (14)