[rbridge] Aging timer For MAC Entries

[Dinesh G Dutt]

Since the proposal to learn from data frames is the default mode in 
RBridges now, we must also  mention how to age the MAC addresses learnt 
in the RBridge forwarding table; this includes MAC addresses learnt on 
directly attached local ports (local MACs) and those learnt about remote 
entities (remote MACs), containing the mapping of remote MAC address to 
RBridge nickname.

The basic guideline is to follow the IEEE 802.1Q bridge standards. The 
2005 version of the 802.1Q draft has the following to say (section 
8.8.3) about entries learnt from data frames (called Dynamic Filtering 
entries in IEEE lingo):
"The Ageing Time may be set by management (Clause 12). A range of 
applicable values and a recommended default is specified in Table 8-3; 
this is suggested to remove the need for explicit configuration in most 
cases. If the value of Ageing Time can be set by management, the Bridge 
shall have the capability to use values in the range specified, with a 
granularity of 1 s."

Table 8-3 specifies that the recommended default value is 300s and that 
the range of allowed values is 10-1,000,000 secs.

I recommend that we adopt the similar text and recommend the same range 
and default value.

Dinesh

-- 
We make our world significant by the courage of our questions and by 
the depth of our answers.                               - Carl Sagan