Allied Telesis AT-S63 - Manual (Page 560)

Chapter 32: Internet Protocol Version 4 Packet Routing
560 Section VII: Internet Protocol Routing
Routing
Interfaces and
Management
Features
Routing interfaces are primary intended for the IPv4 packet routing
feature. There are, however, a number of management functions that rely
on the presence of at least one routing interface on the switch to operate
properly. The switch uses the IP address of an interface as its source
address when it performs the management function. The management
functions are listed here:
ˆ Network servers
ˆ Enhanced stacking
ˆ Remote Telnet, SSH, and web browser management sessions
ˆ Pinging a remote device
ˆ DHCP or BOOTP server
Network Servers
A local subnet on the switch must have an interface if the device is using
the subnet to access any of the following types of network servers:
ˆ SNTP server for setting the switch’s date and time.
ˆ RADIUS or TACACS+ authentication server for manager access
accounts and 802.1x port-based network access control.
ˆ Syslog server for storing events from the switch’s event logs.
ˆ TFTP server for uploading and downloading files to the switch.
The switch uses the IP address of the interface as its source address
when communicating with the network server. Without a routing interface
on the subnet, the switch will not have a source IP address to include in its
packets. For example, the switch, in order to set its date and time using an
SNTP server, must have a routing interface on the local subnet from
where it is reaching the server.
The servers can be located on different routing interfaces on the switch.
For instance, the switch can access an SNTP server through one interface
and a RADIUS authentication server from another. This differs from earlier
versions of the AT-S63 management software where all the servers had to
be members of what was referred to as the “management VLAN.”
Time to Live Exceeded (11) If the TTL field in a packet falls to
zero the switch will send a “Time to
live exceeded” packet. This could
occur if a route was excessively
long or if too many hops were in
the path.
Table 28. ICMP Messages Implemented on the AT-9400 Series Switch
ICMP Packet (Type) Switch Response