Nortel Networks 8000 - Manual (Page 296)

8 Frame relay configuration
Nortel Secure Router 8000 Series
Configuration -WAN Access
• N391 where DTE sends a status request packet at certain intervals (determined by T391).
There are two types of status request packets, namely link integrity verification packet
and link status query packet. N391 defines the sending ratio of the two types of status
request packets. The formula is link integrity verification packet number: link status
query packet number = (N391-1):1.
• N392 indicates the error threshold of total events observed.
• N393 indicates total events observed.
• T391 indicates a time variable. It defines the time interval at which DTE sends a status
request packet.
DTE sends a status request packet at certain intervals to query the link status. DCE sends a
status response packet after receiving this request packet. If no response is received from DCE
within the specified period, the DTE regards that the error has occurred once. If the number of
error occurrences exceeds the threshold, DTE reckons that physical channel is unavailable,
nor are all VCs.
N392 and N393 define the error threshold. For example, all N393 status request packets are
sent on device at DTE side, wherein N392 gets no response within the stipulated period. DTE
reckons that physical channel is unavailable, nor are all the VCs.
The meanings of the parameters related to DCE are as follows:
• N392 and N393: refer to the above section "Meanings of the parameters related to DTE".
Note that DCE requires T392 rather than T391 to determine the fixed time interval at
which DTE sends a status request packet. The time interval of a status request packet
sent by DTE is determined by T391.
• T392: A time variable. It defines the maximum time for the DCE must wait for a status
request packet. Its value should be greater than T391.
FR sub-interface
You can divide FR sub-interfaces to the following two types:
• You configure Point-to-Point (P2P) sub-interface connects with a single remote device, a
P2P sub-interface with one PVC. You can identify the peer device without configuring
static address mapping.
• You use Point-to-Multipoint (P2MP) sub-interface to connect multiple remote devices .
You configure a P2MP sub-interface with multiple PVCs. Each PVC sets up a address
mapping with the protocol address of its connected remote device. You can set up the
address mapping through manual configuration, or dynamically set up through Reverse
Address Resolution Protocol (RARP).
Before configuring an FR sub-interface, configure the link layer protocol of the main interface
as FR.
By default, the interface type of an FR sub-interface is P2MP.
QoS of frame relay
FR has its QoS mechanism. For details, refer to the Nortel Secure Router 8000 Series
Configuration Guide - QoS.
8-6 Nortel Networks Inc. Issue 5.3 (30 March 2009)