On Jul 16, 2011, at 3:42 PM, Johnny Billquist wrote:
On 2011-07-16 19.18, hvlems at zonnet.nl wrote:
I'm not sure what the router rules are. There are 63 areas, each with
one actove area router. There may be more routers configured as an area
router in one area; the one with the highest (?) DECnet address is
selected as the active one.
As far as I know, there can be more than one active area router. Just look at what the next hop are for different nodes in your node list... :-)
The way it works is that address 0 in the level 1 routing data corresponds to "nearest L2 router". Any L2 router contributes to that. The L1 routers don't know or care who is the nearest L2 router, they only care which direction to send to get there.
paul
On Jul 16, 2011, at 1:18 PM, <hvlems at zonnet.nl> <hvlems at zonnet.nl> wrote:
The Montagar licenses include all the DECnet licenses. There is no reason to limit yourself (today) to endnode functionality. SHOW NETWORK(/OLD) gives useful information.
I'm not sure what the router rules are. There are 63 areas, each with one actove area router. There may be more routers configured as an area router in one area; the one with the highest (?) DECnet address is selected as the active one.
No, an L1 router will pick the nearest L2 router (lowest cost path to it). End nodes will send to the elected designated router for the first packet, and will (depending on the exact version) send subsequent traffic back to the router that sent it the reply. (That's the "previous hop cache" which in the original Phase IV started out as the "on-Ethernet" cache but was later generalized.)
There are limits on the number of routers. There are counters in NCP, executer max circuits and exec maximum routers.
Max routers is the max adjacent routers on Ethernet; it does not limit the total number of routers in the area.
paul
On 2011-07-16 19.22, hvlems at zonnet.nl wrote:
The restriction was for level-1 (or circuit) routing and was introduced
when the Alpha was new (no Itanium yet, Alpha was king of the hill).
Ethernet was to be the network for all sites.
Ethernet is a different domain than DECnet routing. You need DECnet routing even with Ethernet. And Alphas can officially act as level 1 routers. It is level 2 (area) routers they supposedly can not be.
AFAIK there is still no DDCMP support for decnet on alpha.
Right.
Johnny
Verzonden vanaf mijn draadloze BlackBerry -toestel
------------------------------------------------------------------------
*From: * "Steve Davidson" <jeep at scshome.net>
*Sender: * owner-hecnet at Update.UU.SE
*Date: *Sat, 16 Jul 2011 11:28:12 -0400
*To: *<hecnet at Update.UU.SE>
*ReplyTo: * hecnet at Update.UU.SE
*Subject: *[HECnet] DECnet routing on Alpha platforms
While it is true that HP does not officially support Alpha's as routers
(according to their web site), it works just fine!
I suspect, but do not know for sure, that this was more of a marketing
ploy to push Itanium over Alpha.
If you go the emulated route (i.e. VAX 3900) this becomes a non-issue as
VAXen ARE supported as DECnet routers.
-Steve
On 2011-07-16 19.18, hvlems at zonnet.nl wrote:
I'm not sure what the router rules are. There are 63 areas, each with
one actove area router. There may be more routers configured as an area
router in one area; the one with the highest (?) DECnet address is
selected as the active one.
As far as I know, there can be more than one active area router. Just look at what the next hop are for different nodes in your node list... :-)
There are limits on the number of routers. There are counters in NCP,
executer max circuits and exec maximum routers.
Yes. But that is a limit on broadcast routers, and relates to adjacent routers that you want to keep track of.
On first generation VAX systems routing overhead was deemed too high.
I think it's wrong to say it was deemed "too high", as that is very subjective. But running as an endnode takes much less resources, so unless you want to run as a router, it would perhaps be benificial.
IMO this may be the case with 11/750's and slower but a MicroVAX II
could easily keep up with the traffic on a LAN with more than 1100
decnet hosts in 8 areas.
Well, a PDP-11 can keep up with it as well. (Although I have not tried anything slower than a PDP-11/70.) But it do take some CPU power, as well as memory.
Johnny
Hans
Verzonden vanaf mijn draadloze BlackBerry -toestel
------------------------------------------------------------------------
*From: * "Steve Davidson" <jeep at scshome.net>
*Sender: * owner-hecnet at Update.UU.SE
*Date: *Sat, 16 Jul 2011 11:23:46 -0400
*To: *<hecnet at Update.UU.SE>
*ReplyTo: * hecnet at Update.UU.SE
*Subject: *[HECnet] DECnet et al
Mark,
When I install DECnet on VMS I always use the DNVETRTG license. This way
I do not have to care about the system's role - I may change it at will
On another note, the node SGC:: is an emulated system that is always
running as an area router. This way I always have a gateway to the rest
of HECnet and the cost to run the system is minimal. DECnet has limits
as to the total number of area routers so just adding a router may not
be the best answer. The HECnet backbone is not at that limit yet... If
you were to use an emulated system as a router then it would not matter
which of the other systems you brought up - they would all be able to
see the rest of HECnet.
I should mention though that a cluster with a cluster alias MUST be a
router. It can be a level-1 or level-2 (area) though...
-Steve
On 2011-07-16 17.28, Steve Davidson wrote:
While it is true that HP does not officially support Alpha's as routers
(according to their web site), it works just fine!
Actually, they are supported as level 1 routers, just not level 2 (area) routers.
I suspect, but do not know for sure, that this was more of a marketing
ploy to push Itanium over Alpha.
Eh? This was the case from day 1, when Alpha was introduced, and noone had yet ever heard the word "Itanium".
If you go the emulated route (i.e. VAX 3900) this becomes a non-issue as
VAXen ARE supported as DECnet routers.
Yes. And so are for instance PDP-11s. (With the right OS.) :-)
Johnny
On 2011-07-16 17.23, Steve Davidson wrote:
Mark,
When I install DECnet on VMS I always use the DNVETRTG license. This way
I do not have to care about the system's role - I may change it at will
Assuming you have that license, it obviously makes your life easier, yes.
On another note, the node SGC:: is an emulated system that is always
running as an area router. This way I always have a gateway to the rest
of HECnet and the cost to run the system is minimal. DECnet has limits
as to the total number of area routers so just adding a router may not
be the best answer. The HECnet backbone is not at that limit yet... If
you were to use an emulated system as a router then it would not matter
which of the other systems you brought up - they would all be able to
see the rest of HECnet.
As far as I know, there is no limit on the number of area routers in a DECnet. But for a specific node, there is a limit on how many adjacent broadcast routers it can keep track of. But that is both level 1 and level 2 routers. And it just becomes a "problem" for you locally in that you might not be using the optimal route to destinations if there are more routers available, as your machine will not keep track of all of them in that case, and might miss the optimal one. But the network will still work just fine.
I should mention though that a cluster with a cluster alias MUST be a
router. It can be a level-1 or level-2 (area) though...
Indeed.
Johnny
The restriction was for level-1 (or circuit) routing and was introduced when the Alpha was new (no Itanium yet, Alpha was king of the hill). Ethernet was to be the network for all sites.
AFAIK there is still no DDCMP support for decnet on alpha.
Verzonden vanaf mijn draadloze BlackBerry -toestel
From: "Steve Davidson" <jeep at scshome.net>
Sender: owner-hecnet at Update.UU.SE
Date: Sat, 16 Jul 2011 11:28:12 -0400
To: <hecnet at Update.UU.SE>
ReplyTo: hecnet at Update.UU.SE
Subject: [HECnet] DECnet routing on Alpha platforms
While it is true that HP does not officially support Alpha's as routers (according to their web site), it works just fine! I suspect, but do not know for sure, that this was more of a marketing ploy to push Itanium over Alpha. If you go the emulated route (i.e. VAX 3900) this becomes a non-issue as VAXen ARE supported as DECnet routers. -Steve
The Montagar licenses include all the DECnet licenses. There is no reason to limit yourself (today) to endnode functionality. SHOW NETWORK(/OLD) gives useful information.
I'm not sure what the router rules are. There are 63 areas, each with one actove area router. There may be more routers configured as an area router in one area; the one with the highest (?) DECnet address is selected as the active one.
There are limits on the number of routers. There are counters in NCP, executer max circuits and exec maximum routers.
On first generation VAX systems routing overhead was deemed too high. IMO this may be the case with 11/750's and slower but a MicroVAX II could easily keep up with the traffic on a LAN with more than 1100 decnet hosts in 8 areas.
Hans
Verzonden vanaf mijn draadloze BlackBerry -toestel
From: "Steve Davidson" <jeep at scshome.net>
Sender: owner-hecnet at Update.UU.SE
Date: Sat, 16 Jul 2011 11:23:46 -0400
To: <hecnet at Update.UU.SE>
ReplyTo: hecnet at Update.UU.SE
Subject: [HECnet] DECnet et al
Mark, When I install DECnet on VMS I always use the DNVETRTG license. This way I do not have to care about the system's role - I may change it at will On another note, the node SGC:: is an emulated system that is always running as an area router. This way I always have a gateway to the rest of HECnet and the cost to run the system is minimal. DECnet has limits as to the total number of area routers so just adding a router may not be the best answer. The HECnet backbone is not at that limit yet... If you were to use an emulated system as a router then it would not matter which of the other systems you brought up - they would all be able to see the rest of HECnet. I should mention though that a cluster with a cluster alias MUST be a router. It can be a level-1 or level-2 (area) though... -Steve
While it is true that HP does not officially support Alpha's as routers (according to their web site), it works just fine! I suspect, but do not know for sure, that this was more of a marketing ploy to push Itanium over Alpha. If you go the emulated route (i.e. VAX 3900) this becomes a non-issue as VAXen ARE supported as DECnet routers. -Steve
Mark, When I install DECnet on VMS I always use the DNVETRTG license. This way I do not have to care about the system's role - I may change it at will On another note, the node SGC:: is an emulated system that is always running as an area router. This way I always have a gateway to the rest of HECnet and the cost to run the system is minimal. DECnet has limits as to the total number of area routers so just adding a router may not be the best answer. The HECnet backbone is not at that limit yet... If you were to use an emulated system as a router then it would not matter which of the other systems you brought up - they would all be able to see the rest of HECnet. I should mention though that a cluster with a cluster alias MUST be a router. It can be a level-1 or level-2 (area) though... -Steve
