- Enterasys Security Router User's Guide

Frame Relay Features
XSR User’s Guide 9-3
Frame Relay Features
The XSR supports the following FR features:
• The XSR acts as a DTE/DCE device in the UNI (User Network Interface) interface, supporting
FR PVC connections (NNI functionality is not supported)
• 10-bit DLCI addressing using a 2-byte DLCI header (3- and 4-byte headers are not supported)
• Rate enforcement (CIR) with automatic rate fallback via traffic/adaptive shaping when the
network is congested. Automatically restores to normal rates when congestion is removed
• Congestion control by Backward Explicit Congestion Notification (BECN). The XSR does not
send packets with the BECN bit set
• Discard Eligibility (DE) bit - traffic is counted as it is received
• Three standard LMIs: ILMI (FRF1.1) ANSI Annex D, CCITT Annex A. Also supported: Auto
LMI detect and None. The Full Status Continue Report type as defined by Annex A of FRF1.2
allowing LMI status messages to be broken into small sizes, is not supported since it is
relevant only if more than 300 DLCIs are supported on one physical interface
• Multi-protocol interconnect over FR (RFC-2427). IP is supported
• Frame Relay Inverse ARP per RFC-2390
• LMI DCE support includes Asynchronous Status Messages.
• Auto and ILMI support 190 DLCIs per interface. Other LMI protocols support 300 per
interface.
• Multiple logical interfaces over the same physical FR port (sub-interfaces)
• Quality of Service: standard FIFO queuing, or IP QoS on DLCIs
• Industry-standard CLI and statistics
• Maximum PDU size of 1536 bytes
• End-to-end packet fragmentation per FRF.12
• SNMP support per RFC-2115
• Traffic shaping
The XSR proscribes the following maximum configuration limits:
• 1000 FR interfaces or sub-interfaces per node
• 1000 DLCIs per node
• 30 sub-interfaces per FR interface
• 300 PVCs per FR interface for LMI ANSI, Q933A, NONE
• 190 PVCs per FR interface for LMI AUTO, ILMI
• 300 FR map-classes
Multi-Protocol Encapsulation
XSR supports encapsulation of multiple protocols - a flexible way to carry many protocols via FR.
This method is useful when it is necessary to multiplex/de-multiplex across one FR connection, as
described by RFC-2427, which defines a generic, end-to-end encapsulation mechanism for devices
to communicate many protocols over a single port.