3Com CoreBuilder 3500, Implementation Manual

Page: 469 / 592

Checksum Error Detection 469
Checksum Error
Detection
You can enable or disable checksum generation and verification. The
AppleTalk protocol uses checksums to detect errors in data transmissions.
A
checksum totals all data bytes and adds the sum to the checksum field
of the data packet. The receiving station computes a verification
checksum from the incoming data and compares the new checksum with
the value sent with the data. If the values do not match, the transmission
contains an error.
Important
Considerations
Before configuring checksum error detection, review the following
guidelines and considerations:
■
By default, checksum generation and verification is disabled .
■
Disabled is the preferred setting. Enabling the checksum generation or
verification significantly impacts the router’s performance.
■
You may want to disable checksum generation and verification if you
have older devices that cannot receive packets with checksums.
AppleTalk Echo
Protocol (AEP)
The system supports the AppleTalk Echo Protocol (AEP), which sends a
datagram (an Echo Request) to a specified node. The destination node
returns, or
echoes , the datagram to the sender (using an Echo Reply). This
process allows you to determine whether a node is accessible. Your
system’s
appletalk ping
command is equivalent to an IP ping, except
that you specify an AppleTalk address instead of an IP address. You can
use this command to verify whether or not an AppleTalk node is
reachable from the router.