| 7.3 | Flow Masks | ||
| 7.3.1 | Flow mask overview |
One of the best features of MLS is
that it supports access lists. Both standard and extended IP
access lists are available. This support relies on three mechanisms:
The MLS-SE uses flow mask modes to determine how packets are compared to MLS entries in the MLS cache. The flow mask mode is based on the access lists configured on the MLS router interfaces. The MLS-SE learns the flow mask through MLSP messages from each MLS-RP for which the MLS-SE is performing Layer 3 switching. MLS-SE supports only one flow mask for all MLS-RPs that are serviced by the MLS-SE. If the MLS-SE detects different flow masks from different MLS-RPs for which the MLS-SE is performing Layer 3 switching, the MLS-SE changes its flow mask to the most specific flow mask detected. However, if a more specific flow mask is in effect, then a less specific flow mask is applied. The MLS-SE supports three flow mask modes:
When the MLS-SE flow mask changes, the entire MLS cache is purged. |