Ascend Archive
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Re: (ASCEND) IP Addresses needed for 4048

> This is true. I haven't been using pool summary. Is there any advantages 
> when using a router to direct traffic?

If you don't use Pool Summary then there are only two other ways of
selecting Dynamic IP addresses. Personally I don't like either one of
themwhich is why I *do* use Pool Summary.

Method 1: Proxy ARP
-------------------

Assign dynamic IP addresses out of the address space assigned to the
Max's Ethernet interface. Example:

exterior router: 192.168.64.1/24
Max1:            192.168.64.2/24
Max2:            192.168.64.3/24

Max1 Dynamic addresses: 192.168.64.11-192.168.64.60
Max2 Dynamic addresses: 192.168.64.61-192.168.64.110

When the exterior router or Max2 or anything else on the Ethernet attempts
to contact, say, 192.168.64.21, Max1 claims that 192.168.64.21 is itself,
that is it responds to ARP requests for 192.168.64.21 as if they were
directed to Max1 itself. Thus it will receive the packets that must
be sent to customers on Max1.

Advantages:
   - easiest to configure, works automatically
   - fairly conservative in address usage (does not require pool of
     power of 2 size)

Disadvantages:
   - clutters up the ARP tables of all the nodes on the LAN
   - uses up space in the address space normally set aside for nodes
     on the Ethernet
   - less clean network design (breaks one to one relationship
     between subnets and physical LANs/WANs

Method 2: Individual route announcements
----------------------------------------

The dynamic addresses are taken from an arbitrary, previously
unassigned space (that is, you assign a space for this purpose).
The Max announces the route to each address that is in use via
some routing protocol (RIP, OSPF) so that other routers on the
network know about it.

Advantages:
   - Nice design (IMHO)

Disadvatbages:
   - Makes one routing announcement for each and every address that it
     currently in use (clutter)

Pool Summary
------------

Same as method 2 but there is one big routing announcement for the whole
block (which must be of a size equal to a power of two) so there is no
clutter.

-Phil
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