From: Kirk Graham (kgraham@instructors.net)
Date: Tue Nov 23 2004 - 20:36:28 GMT-3
At 05:03 PM 11/23/2004, ccie2be wrote:
> > And, Windoz hosts can use multiple default gateways. Try the first in
> > the list, if its not resonsive try second, etc.
> >
Just a side trivia note... Windoze only uses the multiple gateways for TCP
applications since those are connection-oriented. UDP, ICMP, and all other
IP protocols are connectionless, so only the 1st default-gateway in the
list is attempted.
Cisco routers do the same thing for multiple IP addresses on an "ip host"
statement.
For example,
Central# configure terminal
Central(config)# ip host branch 172.16.24.1 172.16.25.1 172.16.26.1 172.16.27.1
Central(config)# end
Central# ping branch
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.24.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Central# traceroute branch
Type escape sequence to abort.
Tracing the route to branch (172.16.24.1)
1 * * *
2 * * *
3 <Ctrl-Shift-6>
Central# telnet branch
Trying branch (172.16.24.1)...
% Destination unreachable; gateway or host down
Trying branch (172.16.25.1)... Open
User Access Verification
Password:
Password:
Branch> logout
Central#
Notice ping (ICMP) and traceroute (UDP) only attempt 172.16.24.1 the 1st IP
address in the host list. But telnet (TCP) keeps trying till a reachable IP
is found.
I love useless trivia,
Kirk!
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