iv
Setting the DSCP value for outgoing DNS packets ···································································································· 81
Displaying and maintaining IPv4 DNS ························································································································ 82
IPv4 DNS configuration examples ······························································································································· 82
Static domain name resolution configuration example ····················································································· 82
Dynamic domain name resolution configuration example ··············································································· 83
IPv6 DNS configuration examples ······························································································································· 86
Static domain name resolution configuration example ····················································································· 86
Dynamic domain name resolution configuration example ··············································································· 86
Troubleshooting IPv4 DNS configuration ···················································································································· 91
Symptom ································································································································································· 91
Solution ··································································································································································· 91
Troubleshooting IPv6 DNS configuration ···················································································································· 91
Symptom ································································································································································· 91
Solution ··································································································································································· 91
Basic IP forwarding on the device ···························································································································· 92
FIB table ·········································································································································································· 92
Displaying FIB table entries ··········································································································································· 92
Configuring load sharing ·········································································································································· 94
Overview ········································································································································································· 94
Configuring load sharing ·············································································································································· 94
Load sharing configuration example ··························································································································· 94
Network requirements ··········································································································································· 94
Configuration procedure ······································································································································ 95
Verifying the configuration ··································································································································· 96
Optimizing IP performance ······································································································································· 97
Enabling an interface to receive and forward directed broadcasts destined for the directly connected network97
Configuration procedure ······································································································································ 97
Configuration example ········································································································································· 97
Configuring TCP MSS for an interface ························································································································ 98
Configuring TCP path MTU discovery ························································································································· 99
Enabling TCP SYN Cookie ·········································································································································· 100
Configuring the TCP buffer size ·································································································································· 100
Configuring TCP timers ················································································································································ 100
Enabling sending ICMP error messages ···················································································································· 101
Disabling forwarding ICMP fragments ······················································································································ 102
Configuring rate limit for ICMP error messages ······································································································· 102
Specifying the source address for ICMP packets ····································································································· 103
Displaying and maintaining IP performance optimization ······················································································ 103
Configuring UDP helper·········································································································································· 105
Overview ······································································································································································· 105
Configuration guidelines ············································································································································· 105
Configuration procedure ············································································································································· 105
Displaying and maintaining UDP helper ··················································································································· 106
UDP helper configuration example ···························································································································· 106
Network requirements ········································································································································· 106
Configuration procedure ···································································································································· 106
Verifying the configuration ································································································································· 107
Configuring basic IPv6 settings ······························································································································ 108
Overview ······································································································································································· 108
IPv6 features ························································································································································· 108
IPv6 addresses ····················································································································································· 109
IPv6 ND protocol ················································································································································· 112
