The MPLS WG Archive

[Yakov Rekhter <yakov@cisco.com>]

Curtis,

[clipped...]

> Yakov,
> 
> This may be a scalability or management limitation.  Our routers
> already are designed to accommodate 560 slots (14 40 slot bays) and
> will support 1120 slots in the future.  Each slot may have 16 ports or
> may have switched or channelized interfaces.  [btw- yes we've tested
> routers with more than 40 slots but not 14 loaded bays].
> 
> We currently number composite links (tm), which is our layer 2 bundles
> with ifindex values over 2^16 so that we can avoid the number space
> used for physical interfaces.  We will also number switched or
> channelized virtual interfaces (sub-interfaces) in this upper number
> space.
> 
> Its nice to be able to go from bay/slot/interface to physical
> interface.  It is also nice not to have to add an additional more
> dynamically allocated number space that is mapped to and from the
> ifindex number space just because kompella-unnum-02 decided 16 bits
> was plenty when it really wasn't.  Code can handle this easily but
> from a management standpoint this is going to be a pain.
> 
> We can fit into the OSPF 24 bit limit but 16 is too tight.  It is not
> necessary to make these numbers 16 bits.  Or at least I haven't seen
> an argument other than "these are not SNMP or OSPF ifindexes".

The next revision of the Internet Drafts on unnumbered interfaces,
on link bundling, and on TE extensions for ISIS and OSPF will support
32 bits for both Interface ID (in unnumbered and in TE extensions) 
and Component Interface ID (in link bundling).

Yakov.