User`s guide

8-26 Preliminary November 23, 1998 MultiVoice Gateway for the MAX— User’s Guide
Configuring IP Routing
Managing IP routes and connections
within a three second timeout interval, the command output is an asterisk. The following
annotations can appear after the time field in a response:
• !H—Host reached.
• !N—Network unreachable.
• !P—Protocol unreachable.
• !S—Source route failed. Might indicate a problem with the associated device.
• !F—Fragmentation needed. Might indicate a problem with the associated device.
• !h—Communication with the host is prohibited by filtering.
• !n—Communication with the network is prohibited by filtering.
• !c—Communication is otherwise prohibited by filtering.
• !?—An ICMP subcode detected. This event should not occur.
• !??—Reply received with inappropriate type. This event should not occur.
Pinging other IP hosts
The terminal-server Ping command is useful for verifying that the transmission path is open
between the MultiVoice Gateway and another station. It sends an ICMP echo_request packet to
the specified station. If the station receives the packet, it returns an ICMP echo_response
packet. For example, to ping the host Techpubs:
ascend% ping techpubs
PING techpubs (10.65.212.19): 56 data bytes
64 bytes from 10.65.212.19: icmp_seq=0 ttl=255 time=0 ms
64 bytes from 10.65.212.19: icmp_seq=3 ttl=255 time=0 ms
^C
--- techpubs ping statistics ---
2 packets transmitted, 2 packets received, 0% packet loss
round-trip min/avg/MultiVoice Gateway = 0/0/0 ms
You can terminate the Ping exchange at any time by pressing Ctrl-C. When you press Ctrl-C,
the command reports the number of packets sent and received, the percentage of packet loss,
any duplicate or damaged echo_response packets, and round-trip statistics. In some cases,
round-trip times cannot be calculated.
During the Ping exchange, the MultiVoice Gateway displays information about the packet
exchange, including the TTL (Time-To-Live) of each ICMP echo_response packet.
Note: The maximum TTL for ICMP Ping is 255, but the maximum TTL for TCP is often 60
or lower, so you might be able to Ping a host but not be able to run a TCP application (such as
Telnet or FTP) to that station. If you Ping a host running a version of Berkeley UNIX earlier
than 4.3BSD-Tahoe, the TTL report is 255 minus the number of routers in the round-trip path.
If you Ping a host running the current version of Berkeley UNIX, the TTL report is 255 minus
the number of routers in the path from the remote system to the station performing the Ping.
The Ping command sends an ICMP mandatory echo_request datagram, which asks the remote
station Are you there? If the echo_request reaches the remote station, the station sends back an
ICMP echo_response datagram, which tells the sender Yes, I am alive. This exchange verifies
that the transmission path is open between the MultiVoice Gateway and a remote station.