Re: what is the story on if_index allocation ?

From: Luigi Rizzo (rizzo_at_icir.org)
Date: 04/21/04

  • Next message: Petri Helenius: "Re: what is the story on if_index allocation ?" 
    Date: Tue, 20 Apr 2004 23:38:18 -0700
To: Petri Helenius <pete@he.iki.fi>

    On Wed, Apr 21, 2004 at 09:25:59AM +0300, Petri Helenius wrote:
    > Luigi Rizzo wrote:
    >
    > >Can someone explain what is the goal ? Reuse a number if an
    > >interface has the same name of a previously existing one and
    > >the index is free ? And does it make sense, anyways, or
    > >we could just simplify that code and just reuse the first
    > >available entry in ifindex_table[] ?
    > >
    > >
    > The optimal course of action (from management software point of view) is
    > to retain as static ifName to ifIndex mapping. If the index changes for

    I do not think the current code supports this, as any free
    index at the top of the array is reused. So if you had 'vlan12' there
    and it went away, the next interface that comes in will grab that
    index and vlan12 will get a new one. On top of this you can rename
    interfaces without changing the index, you can change MAC and IP
    addresses, in the already mentioned case of a tunnel server
    there is basically no relation between successive creations on
    the same interface.

    My feeling is that there is not even a sensible way to specify
    how one would like to retain the mapping of indexes, let alone
    the fact that the specification changes depending on whom you
    ask. When this happens, it is a good hint to move the issue
    outside the kernel.

    cheers
    luigi
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  • Next message: Petri Helenius: "Re: what is the story on if_index allocation ?"

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