[HECnet] Mapping - getting close

[Johnny Billquist]

On 2013-01-12 16:26, Peter Lothberg wrote:
On 2013-01-12 16:10, Peter Lothberg wrote:
If you ask me, I think this idea is dead. You cannot get a good
representation of how the topology really is from trying to walk nodes
using NCP.

(remove bridged ethernet that are not point-to-point with only 2
nodes).

Walk through the "known cir" and then "cir char" and build your own
connectivity tree with the metrics.

Plot all links

Apply DECnet routing rules and Colour the links that carry traffic
with the current metrics and/up/down condition, use two colours, one
for transmitt one for receive (as links can end up being simplex).

Well, it all depends on what you want to know. If you want to properly
understand the topology you also want to represent the topology of
bridged ethernet segments, as well as ethernets in general. NCP don't
have any clue about this.

Sure, if you want to only have Multinet ptp links, then it's easy. But
that would a rather severe restriction on the network technology.

We have ethernets (both bridged and local), as well as Cisco tunnels.
Both of which walking with NCP fails on.

NCP don't fail on DECboxes on ethernets.

Right. Sloppy working on my part.

The plotting thing would do the right thing even on the ethernet, even
with the ethernet it ended up being a simplex path for some
multi-homed sites.

There are two ways of represnting the the Ethernet,

            1 You draw it as a bus ignore that the links to it have
            different characteristics.

Right, except I didn't follow your comment about characteristics. Are you talking about the fact that different machines have different parameters for the circuits? Or that when you have a bridge, you get very different characteristics if you talk to something on the same segment as compared to something that needs to go over the bridge?

            2 You drow it as all the point-to-point links it represents.

            	Look how IP handles Ethernet, it builds simplex TX only point
            	to point links using ARP and a dest-ip address to MAC address
            	mapping.

Drawing all as ptp links is both ugly, and I'd like to say incorrect.

Drawing it as a bus is what I thing should be done.
But there is yet another complication. How do you figure this out? After all, there also exists multidrop links in DECnet, which do connect several machines, but which really are ptp links.

	Johnny

-- 
Johnny Billquist                                   || "I'm on a bus
                                                                  ||   on a psychedelic trip
email: bqt at softjar.se                         ||   Reading murder books
pdp is alive!                                         ||   tryin' to stay hip" - B. Idol