On Tue, Apr 09, 2002 at 09:56:05AM +1200, Simon Byrnand wrote:
| I'm not sure where you get 92 from - a MAX6096 has 96 modems, but if you
| use E1's for connection you get 30 incomming calls per E1, which works out
| to 90 if you use 3 E1's. (Maybe its different for T1's, I don't know)

T1 is 24 channels.  He probably has PRI, which steals one channel for the
D channel, so he probably has 4 PRIs, which would be exactly 92 channels.

| But anyway, if you use *two* routes, one a 255.255.255.192 and the other an
| adjacent 255.255.255.224 you get 64 addresses + 32 beside each other, which
| is 96. Take one address off if either end of the range falls at 0 or 255 to
| avoid problems with the /24's broadcast and network addresses, and you
| still have 95 available, which is a wastage of only 3 addresses per group.

Unfortunately, Ascend's route summarization doesn't work quite how you'd
expect it (at least on our units, which admittedly are running older 8.x
and 7.x TAOS builds).

In order to use route summarizarion on address pools, you have to define
even subnets of addresses, as you point out.  However, TAOS treats the
summary routes *as* subnets, so it doesn't let you use the first or last
address.  Using 192.168.1.0 as an example:

    Pool#1 start=192.168.1.129       # 192.168.1.128/26
    Pool#1 count=62

    Pool#2 start=192.168.1.193       # 192.168.1.192/27
    Pool#2 count=30

    Pool Summary=Yes

When "Pool Summary" is turned on, the MAX does the following to each pool:

  * subtracts 1 from the start address
  * adds 2 to the count

This yields valid subnets, which it advertises as summary routes.  However,
you pay for it because you lose 2 addresses for each pool, just as you do
with a normal routed subnet.  If you don't mind not having summary routes,
you can certainly set "start" and "count" to whatever exact numbers you
need, you'll just end up with a bunch of /32's in your routing table.

Like I said, our units run older TAOS builds (because most of our units are
4048s, which don't run anything newer than 7.x).  It's possible the summary
behavior has changed in 9.x or later.  YMMV.

-James

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