[HECnet] One more for the Cisco GRE mesh: Seeking Tunnel End-Points

[Supratim Sanyal]

Thanks Johnny for taking the time to write and explain (instead of 
saying "go read DECnet manuals"). So, basically, CTAKAH cannot decide to 
use one path for 1.13 and another one for 1.559 since they are both area 1.

Got it, no easy way out other than move my bunch to a new area. Please 
assign me an area. It will take me a while, though, to move across all 
the toys.

BTW, interestingly, MIM has also decided that IMPVAX is the way to reach 
area 12 (Tim in Perth, Australia), despite Tim having 3 or more other 
direct GRE tunnels to other area routers. Is this because IMPVAX happens 
to be in the same area as MIM (unlike his other tunnels)?


> 
> DECnet routing is kindof stupid. When a node in one area wants to talk 
> to a node in another area, the only thing it does is figure out how to 
> get to that area. And that just means find the lowest cost path to any 
> node in that area. And here it where it gets silly.
> 
> Until a couple of days ago, CTAKAH:: had the same cost for all circuits. 
> That resulted in CTAKAH choosing IMPVAX for all communication to area 1. 
> So even though CTAKAH and MIM have a direct circuit between them, 
> packets from CTAKAH (in Russia) and MIM (in Sweden) were travelling over 
> New York.
> 
> CTAKAH have now dropped the cost for the circuits to MIM to a little 
> lower, meaning it will prefer this link. But that also means that even 
> through CTAKAH and IMPVAX have a direct connection, all packets from 
> CTAKAH to IMPVAX will pass over MIM.
> 
> In essence, this is how DECnet works, and you cannot get around this. 
> When multiple connections to a different area exists, it is going to be 
> suboptimal. The one thing would could do to improve things a bit would 
> be to move you to an area of your own. Then both links would become 
> useful for more than redundancy backup.
> 
>    Johnny
> 
> On 2019-02-26 20:53, Supratim Sanyal wrote:
>> This email is directed to owners of Cisco routers with GRE tunnels; to 
>> the best of my limited knowledge, Dave McGuire, Ian McLaughlin, Brian 
>> Hechinger, Mark Darvill, Cory Smelosky, Peter Löthberg ... who else?
>>
>> I already have a stable GRE tunnel to A12RTR for a while now, and am 
>> looking for end-points on other Cisco routers on HECnet to connect to. 
>> I will be coming in from IP address 45.62.248.66, DECnet node 1.919.
>>
>> If possible, please let me know what GRE end-points I can connect to. 
>> You can, of course, DM me too.
>>
>> Thank you.
>>
>> Supratim
>> +1-240-483-8572 (cell)
>>
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> 
> 


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