Alcatel-Lucent 7750 SR OS - Page 93

Interface Configuration
7750 SR OS Interface Configuration Guide Page 93
Inverse Multiplexing over ATM (IMA) Features
Hardware Applicability
IMA is supported on channelized ASAP MDAs.
Software Capabilities
Alcatel-Lucent’s implementation supports IMA functionality as specified in ATM Forum’s
Inverse Multiplexing for ATM (IMA) Specification Version 1.1 (af-phy-0086.001, March 1999).
The following details major functions
• TX Frame length — Only IMA specification default of 128 cells is supported.
• IMA version — Both versions 1.0 and 1.1 of IMA are supported. There is no support for
automatically falling to version 1.0 if the far end advertises 1.0 support, and the local end
is configured as 1.1. Due to potential protocol interoperability issues between IMA 1.0
implementations, it is recommended that IMA version 1.1 is used whenever possible.
• Alpha, beta, and gamma values supported are defaults required by the IMA specification
(values of 2, 2, and 1 respectively).
• Clock mode — Only IMA specification default of common clock mode is supported
(CTC).
• Timing reference link — The transmit timing reference link is chosen first among the
active links in an IMA group. If none found, then it is chosen among the usable links or
finally, among the unusable links.
• Cell Offset Configuration — The cell offsets for IMA links are not user configurable but
internally assigned according to the recommended distribution described in the IMA spec.
• TX IMA ID — An internally assigned number equal to the IMA bundle number.
• Minimum Links — A configurable value is supported to control minimum member links
required to be up for an IMA group to stay operationally up.
• Maximum Group Bandwidth — A configurable value is supported to specify maximum
bandwidth available to services over an IMA group. The maximum may exceed the
number of minimum/configured/active links allowing for overbooking of ATM shaped
traffic.
• Symmetry mode — Only IMA specification default of symmetric operation and
configuration is supported.
• Re-alignment — Errors that require a re-alignment of the link (e.g., missing or extra cells,
corrupted frame sequence numbers), are dealt with by automatically resetting the IMA
link upon detection of an error.