PING通但TRACERT不通

[SQLANDGAO]

ping 210.51.166.5 是通的，但是TRACERT 210.51.166.5 却不通，为什么？
C:\Documents and Settings\Administrator>tracert 210.51.166.5

Tracing route to 210.51.166.5 over a maximum of 30 hops

1 * * * Request timed out.
2 * * * Request timed out.
3 * * * Request timed out.
4 * * * Request timed out.
5 * * * Request timed out.
6 * * * Request timed out.
7 * * * Request timed out.
8 * * * Request timed out.
9 * * * Request timed out.
10 * * * Request timed out.
11 * * * Request timed out.
12 * * * Request timed out.
13 * * * Request timed out.
14 * * * Request timed out.
15 * * * Request timed out.
16 * * * Request timed out.
17 93 ms 84 ms 91 ms 210.51.166.5

Trace complete.

[banhao]

中间有防火墙

[banhao]

ISA2000中的解法：
要能PING通，需要在Access Policy下的IP Packet Filters中增加ICMP all outbound和ICMP Ping response(in) 两条策略，如果需要tracert还需要增加ICMP timeout。