How PortMasters Work        2

This chapter discusses the following topics:

•  "Booting the PortMaster" on page 2-1

•  "PortMaster Initialization" on page 2-3

•  "On-Demand Connections" on page 2-4

•  "PortMaster Security Management" on page 2-4

•  "Port Status and Configuration" on page 2-5

  See the Command Line Administrator's Guide for more detailed command descriptions and instructions.

Booting the PortMaster

1. Self-diagnostics are performed. The results are displayed to asynchronous console port C0 or S0 if the console DIP switch (first from the left, also known as DIP 1) is up.

2. ComOS is loaded.

• If the netboot DIP switch (second from the left, also known as DIP 2) is down, the PortMaster boots from the ComOS stored in nonvolatile Flash RAM. The PortMaster uncompresses and loads the ComOS into dynamic RAM (DRAM). If a valid ComOS is not found in Flash, the PortMaster attempts to boot from the network as described in the next paragraph.

• If the netboot DIP switch is up, or if a valid ComOS is not found in Flash, the PortMaster sends a Reverse Address Resolution Protocol (RARP) message to the Ether0 Ethernet interface to find its IP address. If it gets a reply, the PortMaster then attempts to boot itself across the network using the Trivial File Transfer Protocol (TFTP) to download a netbootable ComOS image from the host that replied to the RARP.

The TFTP process begins by transferring the /tftpboot/address.typ file, replacing address with the uppercase 8-character hexadecimal expression of the IP address of the PortMaster and typ with the 3-character boot extension describing the model of PortMaster, as shown in Table 2-1. If /tftpboot/address.typ is not found, the PortMaster requests /tftpboot/GENERIC.OS.  

Table 2-1 Boot Extensions

Boot Extension	PortMaster Model
PM3	PM3
PM2	PM-2, PM-2E, PM-2R, PM-2ER, PM-2i, PM-2Ei
IRX	IRX, any model
P25	PM-25
PMO	PortMaster Office Router, any model

The netbootable ComOS can also be downloaded via serial cable through the console port. See "Booting from PROM" on page 20-18."

3. The user configuration is loaded from Flash RAM.

4. The IP address is located.

If no address is configured for the Ethernet interface and no address was obtained from netbooting, the PortMaster sends a RARP message to discover its IP address. If the PortMaster receives a reply to the RARP message, its IP address is set in dynamic memory.

PortMaster Initialization

1. Ethernet interfaces are started.

2. Modem initialization strings are sent to asynchronous ports that have modem table entries defined.

3. Network hardwired ports are initiated.

4. Continuous dial-out connections are initiated.

5. On-demand dial-out connections for locations that have routing enabled are initiated, and routing information is exchanged between the PortMaster and those locations.

6. Broadcasting and listening for routing packets are initiated on interfaces configured for routing.

7. TCP connections to PortMaster hosts are established.

8. TCP connections are established to ports configured as host devices by means of the PortMaster device service.

9. The PortMaster listens for TCP connections to any ports configured as network devices.

10. The PortMaster listens for activity on TCP and UDP ports, such as for administrative Telnet sessions on TCP port 23, PMconsole connections on TCP port 1643, and SNMP requests on UDP port 161.

11. Syslog starts, if configured.

12. RADIUS starts, if configured.

13. ChoiceNet starts, if configured.

The PortMaster is now ready to begin providing service.

On-Demand Connections

• When the PortMaster receives packets going to an on-demand location that is suspended (not currently active), it dials out to that location if a line is available.

• If idle timers expire on a connection, the connection is brought down, freeing the port for other uses.

• At regular intervals the packet queues are checked for dial-out locations configured for multiline load balancing to determine if more bandwidth is needed. If it needs more bandwidth, the PortMaster dials out on an additional port and adds that port to the existing interface.

• When users dial in, they are authenticated and provided with their configured service.

PortMaster Security Management

If port security is on and the user was not found in the user table, the PortMaster queries the RADIUS server if one has been configured. If the username is not found in the user table, port security is on, and no RADIUS server is configured in the global configuration of the PortMaster, access is denied with an "Invalid Login" message. If the RADIUS server is queried and does not respond within 30 seconds (and neither does the alternate RADIUS server), access is denied with an "Invalid Login" message.

If security is set to off, any username that is not found in the user table is sent to the port's host for authentication and login. If security is set to on, the user table is checked first. If the username is not found and a RADIUS server is configured, RADIUS is consulted. When you are using RADIUS security, you must use the set security s0 command to set security to on.

Access can also be denied if the specified login service is unavailable-for example, if the PortMaster Login Service has been selected for the user but the selected host does not have the in.pmd PortMaster daemon installed. Access is denied with the "Host Is Currently Unavailable" message if the host is down or otherwise not responding to the login request.

If an access filter is configured on the port and the login host for the user is not permitted by the access filter, the PortMaster refuses service with an "Access Denied" message. If the access override parameter is set on the port, the PortMaster instructs the user to authenticate himself, even though the default access filter is set to deny access.

Refer to the RADIUS Administrator's Guide for more information about RADIUS.

Port Status and Configuration

Command> show s0|w1|p0

 Table 2-2 describes each possible status. See "Verifying Port State for Old and New Cards" on page 20-9 for verification information.

  

Table 2-2 PortMaster Port Status

Status	Description
IDLE	The port is not in use.
USERNAME	The data carrier detect (DCD) signal has been asserted and observed on the port. On older Livingston expansion cards (ports S10 through S29) and system cards (ports S0 through S9), DCD floats high when nothing is attached to the port. On newer cards, in two-way and device environments, DCD is high when the device is busy. When terminals are attached to the device port and modem control is set to off, USERNAME status indicates that the login: prompt has been sent to the port and should be displayed on the terminal. The PortMaster is waiting for a login request.
HOSTNAME	The host: prompt has been sent to the port. The PortMaster is waiting for a reply.
PASSWORD	The Password: prompt has been sent to the port. The PortMaster is waiting for a reply.
CONNECTING	A network connection is attempting to become established on the port.
ESTABLISHED	A connection is active on the port.
DISCONNECTING	The connection has just ended, and the port is returning to the IDLE state.
INITIALIZING	The modem attached to the port is being initialized by the modem table.
COMMAND	The command line interface is being used on the port.
NO-SERVICE	An ISDN port is not receiving service from the telephone company.