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100 Routing Configuration
IP MTU......................................... 1500
Bandwidth...................................... 100000 kbps
Destination Unreachables....................... Enabled
ICMP Redirects................................. Enabled
To delete a loopback interface, enter the following command from the Global Config mode:
console(config)#no interface loopback 0
console(config)#
IP Helper
The IP Helper feature provides the ability for a router to forward configured UDP broadcast packets to a
particular IP address. This allows applications to reach servers on non-local subnets. This is possible even
when the application is designed to assume a server is always on a local subnet or when the application
uses broadcast packets to reach the server (with the limited broadcast address 255.255.255.255, or a
network directed broadcast address).
Network administrators can configure relay entries globally and on VLAN routing interfaces. Each relay
entry maps an ingress interface and destination UDP port number to a single IPv4 address (the helper
address). Multiple relay entries may be configured for the same interface and UDP port, in which case
the relay agent relays matching packets to each server address. Interface configuration takes priority over
global configuration. If the destination UDP port for a packet matches any entry on the ingress interface,
the packet is handled according to the interface configuration. If the packet does not match any entry on
the ingress interface, the packet is handled according to the global IP helper configuration.
You can configure discard relay entries. Discard entries are used to discard packets received on a specific
interface when those packets would otherwise be relayed according to a global relay entry. Discard relay
entries may be configured on VLAN routing interfaces, but are not configured globally.
Additionally, you can configure which UDP ports are forwarded. Certain UDP port numbers can be
specified by name in the UI, but network administrators can configure a relay entry with any UDP port
number. You can configure relay entries that do not specify a destination UDP port. The relay agent
assumes that these entries match packets with the UDP destination ports listed in Table 4-1 (the list of
default ports).