10.8 The NSORDER
Environment Variable
10.8 The NSORDER
Environment Variable
The Address Resolution Protocol (ARP) dynamically translates Internet addresses into the unique hardware addresses on local area networks. Nodes on the same segment of the same LAN use ARP to determine the hardware address of other nodes.
Unlike the routing table, you can only delete the ARP cache entries one host at a time:
# arp -a itsorusi.itsc.austin.ibm.com (9.3.1.74) at 10:0:5a:a8:42:14 [token ring] sv1166a.itsc.austin.ibm.com (9.3.1.25) at 0:6:29:f0:e2:77 [token ring] itsonv.itsc.austin.ibm.com (9.3.1.5) at 8:0:5a:48:4a:48 [token ring] netcomp.itsc.austin.ibm.com (9.3.1.232) at 10:0:5a:38:fb:3 [token ring] jc6003a.itsc.austin.ibm.com (9.3.1.111) at 0:6:29:f0:e1:2 [token ring] # arp -d jc6003a Entry jc6003a (9.3.1.111) was deleted from local arp table. # arp -a itsorusi.itsc.austin.ibm.com (9.3.1.74) at 10:0:5a:a8:42:14 [token ring] sv1166a.itsc.austin.ibm.com (9.3.1.25) at 0:6:29:f0:e2:77 [token ring] itsonv.itsc.austin.ibm.com (9.3.1.5) at 8:0:5a:48:4a:48 [token ring] netcomp.itsc.austin.ibm.com (9.3.1.232) at 10:0:5a:38:fb:3 [token ring] #
Entries in the ARP mapping table are deleted after 20 minutes; incomplete entries are deleted after three minutes. To make a permanent entry in the ARP mapping tables, use the arp command with the pub parameter:
Because the hardware address of the network adapter is used, moving a network adapter from one system to another may cause network traffic to be directed to the wrong system. You should either delete the ARP entry on every node in the segment, or ensure that at least 20 minutes have passed before you bring up the system receiving the network adapter.
10.10 Changing the State
of the Token-Ring Network Interface