Time Constants
Packet Tracer 5.1 uses the following time constants:
| RIP/RIPv6 default update | 30 secs |
| RIP/RIPv6 default timeout | 3 mins |
| RIP/RIPv6 default flush timeout | 4 mins |
| RIP/RIPv6 default hold-down | 3 mins |
| MAC table entry timeout | 5 mins |
| ARP request timer | 2 secs |
| ARP table entry timeout | 4 hrs |
| CDP update timer | 1 min |
| CDP neighbor hold-down timer | 3 mins |
| DHCP client timeout | 5 secs |
| CSMA/CD waiting time to resend | random |
| LMI timeout | 15 secs |
| LMI signaling | 5 secs |
| Inverse ARP | 30 secs |
| HDLC keepalive | 5 secs |
| HDLC timeout | 15 secs |
| NAT/NAT-PT entries timeout | Depends on the encapsulation protocol |
| NAT/NAT-PT entry encapsulated in a UDP | 5 mins |
| NAT/NAT-PT entry encapsulated in a TCP | 24 hrs |
| NAT/NAT-PT entry encapsulated in a ICMP | 1 min |
| CHAP timeout | 5 secs |
| CHAP re-authenticate timeout | 10 secs |
| DIALING no answer timeout | 5 secs |
| DIALING no dial tone timeout | 2 secs |
| PPP keepalive interval | 5 secs |
| Timeout | 15 secs |
| EIGRP/EIGRPv6 Hello time interval period | 5 secs |
| EIGRP/EIGRPv6 Hold time interval period | 15 secs |
| ICMP | 1 ms |
| STP Max Age | 20 secs |
| STP Hello | 2 secs |
| STP Forward Delay | 15 secs |
| STP Topology Change Notify Timer | 2 secs |
| STP Topology Change Timer | 35 secs |
| RSTP Migration Delay Timer | 3 secs |
| OSPF/OSPFv3 SPF Hold Time | 10 secs |
| OSPF/OSPFv3 LS Refresh Time | 30 mins |
| OSPF/OSPFv3 SPF Delay Timer | 5 secs |
| OSPF/OSPFv3 LSA Retransmission Time | 5 secs |
| OSPF/OSPFv3 minimum LSA Arrival Time | 1 sec |
| OSPF/OSPFv3 Delayed Acknowledgment Timer | 2.5 secs |
| OSPF/OSPFv3 Dead Interval | 40 secs |
| OSPF/OSPFv3 Hello | 10 secs |
| OSPF/OSPFv3 Wait Interval | 40 secs |
| TCP Connection Timeout | 60 secs |
| TCP Retransmission Timeout | <= 1 sec |
| TCP Inactivity Timeout | 5 mins |
| TCP Close Timeout | 10 secs |
| DNS Request Timeout | 3 secs |
| DHCP Timeout | 5 secs |
| DHCP Discovery Timeout | 55 secs |
| DTP Hello | 30 secs |
| DTP Timeout | 5 mins |
| Password Timeout | 30 secs |
| ND Neighbor Request Timer | 2 secs |
| ND Neighbor Stale Timer | 30 secs |
| ND Neighbor Timeout Timer | 4 hrs |
| ND Router Solicitation Interval | 4 secs |
| ND Router Advertisement Interval | <= 16 secs |
| DHCPv6 Solicitation Timeout | 1 sec |
| DHCPv6 Request Timeout | 1 sec |
| LACP Initial Advertise Interval | 1 sec |
| LACP Advertise Interval | 30 secs |
| LACP Peer Timeout | 90 secs |
| PAgP Initial Advertise Interval | 1 sec |
| PAgP Advertise Interval | 30 secs |
| PAgP Peer Timeout | 90 secs |