[HECnet] Multinet peerings...?

[hvlems at zonnet.nl]

Johnny, 
When the area routers in the other area are on the same LAN then the bridge w‎ill only be involved if there is another area router in that other area on the remote side of the bridge program.
And will (very likely) slow down communications.
Can the bridge program detect whether there are area routers for the dame area at both ends and favor the local one, possibly block advertising of the remote area router?
Hans

Verzonden vanaf mijn BlackBerry 10-smartphone.
  Origineel bericht  
Van: Johnny Billquist
Verzonden: donderdag 14 januari 2016 22:06
Aan: hecnet at Update.UU.SE
Beantwoorden: hecnet at Update.UU.SE
Onderwerp: Re: [HECnet] Multinet peerings...?

On 2016-01-14 21:38, Peter Lothberg wrote:
>>
>>> On Jan 14, 2016, at 3:02 PM, Peter Lothberg <roll at Stupi.SE> wrote:
>>>
>>>> The values are somewhat arbitrary; it doesn't really matter what
>>>> scheme you use but if you are inconsistent the routing may be
>>>> surprising.
>>>>
>>>> The routing spec has a suggested algorithm (100,000/line speed)
>>>> which may have made sense in the old days but for modern networks
>>>> isn't terribly useful.
>>>> paul
>>>
>>> What I wanted to get to was a scenario where traffic was symetric
>>> between two nodes, eg, use the same links from a-b as b-a, it makes it
>>> much easier to understand what's wrong when things behave funny...
>>
>> If costs are the same at both ends of a link, that will certainly
>> help. Then again, it is quite possible for two paths to have equal
>> cost, and if so, DECnet implementations will pick one of the two, in
>> a way that is not specified.
>> paul
>
> If all links in HECNet where point-to-point, with the same metric on
> both sides, it will most likely be almost *perfect* by itself.
>
> The complex movie is when they *THINK* they are all on the same
> ethernet with metric 1.....

Well, in all honesty, default cost for ethernet links in VMS is 4, and 
in RSX is 3...
So, if you want to favor a different link, set the cost to less.

But you are blindly assuming that Multinet (or other) point-to-point 
links are better. That one I still do not see. There are definitely 
cases where it can be worse.
The worst thing about the bridge is, as I wrote in another mail, is when 
you are on an ethernet segment, and you want to talk to a different 
area, which have several area routers on that same ethernet segment you 
are on, in which case you might end up going through pretty bad hopping.

Johnny