Description: Each learning domain has a learning quota. The ports in the domain are guaranteed the ability to use approximately this number of address entries in the Translation Table, so that an excessive number of learned addresses in one domain cannot interfere significantly with learning in another domain. The GIGAswitch keeps track of the count of addresses learned in each domain and deletes addresses from the domains that have most exceeded their learning quotas to make room for addresses learned in other domains. If these quotas are configured so that they add up to less than the size of the SCP Translation Table, there are almost always SCP Translation Table entries available to accommodate new learned addresses. Further, these addresses will not be deleted to make room for others unless the domain's quota is reached or is close to being reached.

If the SCP Translation Table is not full, the quotas are allowed to be exceeded. Under such circumstances, the count of learned addresses in a logical bridge may grow until it is close to the number of unused entries in the Translation Table plus the applicable learning quota. The learning quotas are not exact, and addresses may start to be deleted when this limit is within a small number of addresses (initially 100) of being reached.

It should be remembered that there are factors other than the learning quotas that may restrict the number of addresses that can be learned, so that a high learning quota does not guarantee that number of addresses may be learned. In particular:

1) If the capacity of the linecard Translation Tables is exceeded, no more addresses may be learned on that linecard.

2) If the sum of the configured learning quotas is greater than the SCP Translation Table size, then no more addresses may be learned once the SCP Translation Table is full, even though no quota may have been exceeded.

When either of these situations occur, an attempt is made to solve the problem by deleting addresses in the same manner as when dealing with the learning quota limits.

The default value for each learning quota is 32768, the same as the capacity of the SCP Translation Table. This large value means that the quotas have no effect. To see the full benefit of learning quotas, they should be set so that the sum of the quotas over all active domains is less than 32500.