Download Linux Routers - A Primer For Network Administrators

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Zinc—A Frame Relay Router
Chapter 5
MTU—This is the maximum data transfer unit in bytes. It is equivalent to the MTU setting
for an Ethernet or other network device.
Station—This is your router’s station type. This must be set to CPE (Customer Premise
Equipment) unless you are running a back-to-back configuration (without a provider),
in which case you set it to Node. It is required.
Signalling—In the Frame Relay world, there are several different types of signalling used
to communicate between your router and your provider’s equipment at the POP. This
value can be ANSI, LMI, or Q933. Your provider should specify the type of signalling you
should use when you order your link. When in doubt, try ANSI.
T391 [range 5–30, default is 10]—This is the Link Integrity Verification Timer (in seconds).
It asks the question, “How often do we check to see if the link is still good?” It applies
only to routers with the Station parameter configured to be CPE.
T392 [range 5–30, default is 15]—This is the Polling Verification Timer (in seconds). It is
applicable only to routers with the Station parameter set to Node.
N391 [range 1–255, default is 6]—This is the Full Status Polling Cycle Counter, and it is
applicable only to CPE routers.
N392 [range 1–10, default is 3]—The Error Threshold Counter is the limit of the number of
consecutive Status Enquiry Message exchange failures before the link is marked inactive.
In other words, it controls how many times we’ll let something bad happen before we’ll
start complaining about it. It is applicable to both CPE and Node Station types.
N393 [range 1–10, default is 4]—This refers to The Monitored Events Counter. When a
network becomes active, you need N393 successful exchanges of Status Enquiry Messages
(keepalives) before the link is considered active. Like N392, it is applicable to both CPE
and Node Station types.
NUMBER OF DLCI [range 0–100, default is 0]—This is the number of DLCIs on the
network. This is not necessary for normal CPE links and should not be used for CPE
Station types. It is useful only for back-to-back configurations.
UDPPORT [range 1–65534, default is 9000]—This is the UDP port used by the various
pipemon programs to talk to the drivers. You should change it only if you have already
committed to using port 9000 for some other service. Note that if you do not specify this
value, the driver will default to using 0, which is probably not what you want. (It would
be more correct to say that the “normal” value is 9000.)
TTL [range 0x01–0xFF, default is 0x7F]—This is the Time To Live parameter for the UDP
packets being sent to and from the UDPPORT in the previous setting. This is a security
feature of WANPIPE, as it limits the distance (in network hops) from which you can run
the monitoring programs. The lower the TTL, the closer (in terms of hops) you need to
be in order to be able to access the monitoring port. If you are too far away, you can
send to the monitoring port, but replies will be discarded by the network before they
reach you.