Understanding the network.pdf - Back to Home

•
• Router(config)#ip forward-protocol udp 67
• Router(config)#int e0
• Router(config-if)#ip helper-address 192.168.1.24
• — IP source routing is an option built into the IP
protocol suite for testing (source routing is indicated in the IP datagram's
header). It provides the capability to dictate the route path that a datagram
will travel. Source routing, like ICMP redirects, can be exploited to create
potential security problems. Unless required, source routing should be
disabled.
• —Each router interface has a default MTU size, which is
used for determining if IP fragmentation is needed. The IOS supports MTU
path discovery, which allows the devices along the route path to adjust for
differences in maximum MTU sizes. Ideally, an MTU of 1500 is preferred,
because it provides for the maximum PDU size allowable for Ethernet, which
will eliminate the need for resizing. Certain Layer 2 protocols support MTU
sizes larger than 1500, which means that when packets are exchanged
between the two different protocols, fragmentation occurs. Whenever
possible it is best to reduce interfaces with larger MTU sizes down to 1500.
The MTU value is part of the IGRP and EIGRP route metric set, but has no
direct role in determining a route's vector (metric cost).
• —The is a configurable parameter
on each of the router's interfaces used for setting the interface's data
transfer rate in kilobytes per second. This value is also used by IGRP, EIGRP,
and OSPF to calculate route metrics. An interface's MTU and bandwidth
values are displayed as part of the
command output:
•
• Router#show interfaces e0
• Ethernet0 is administratively down, line protocol is down
• Hardware is Lance, address is 0010.7b37.b27c (bia
0010.7b37.b27c)
• Internet address is 192.168.0.1/30
• MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
• reliability 255/255, txload 1/255, rxload 1