Re: Number of links towards a DPC (ITU)

David,

David Laight wrote:                         (Mon, 17 Jun 2013 10:10:52)
> 
> In ITU each linkset can have 16 links.
> Brian is right in that MTP3 only has a 4 bit SLS value to select the
> destination link, so traffic to a specific destination will only use
> a maximum of 16 links even if there are routes by 2 adjacents and there
> are 16 links in the linkset to each.
> 
> If you have two linksets with 16 links each, the routing rules for
> different destinations could be arranged to use different links
> in order to utilise all 32 links.

I don't know where you got that idea.  See Figure A.3/Q.705.  Count the
number of links possible in a linkset (not a combined linkset).
8 links per A linkset, 4 links per B/D linkset.

> 
> ANSI only has 4 bits for the SLC (not 5), so a linkset is limited to 16 links.
> However the larger SLS value (8 bits, 5 in some earlier versions)
> means that MTP3 can loadshare between more links.
>

Pardon, SLC is 4 bits, but there are still 16 links per linkset,
32 links per combined linkset.

> 
> It also isn't quite right to say that one of the bits is used for
> linkset selection. If some of the links are down, the sls that
> would be assigned to the 'down' links are evenly spread across
> all of the working links, not just assigned to the working links
> in their original linkset (this might be a config option since
> the ANSI and ITU specs differ here.)

It is quite right to say that 1 bit is used for linkset selection,
as it says in 7.3/T1.111.5.

-- 
Brian F. G. Bidulock
[email protected]
http://www.openss7.org/