Subject: (usr-tc) configuring a second HiPer ARC

From: Antonio Querubin <[email-masked]>
Date: Wed, 24 Jan 2001 22:53:38 +0000

I'm installing a second HiPer ARC into a Total Control chassis and am
having some difficulty integrating it into the system for automatic
failover.  I'm running into several issues.

One problem I've run into is the IP address pools that the HARCs use.  Is
there a way for both HiPer ARCs to share the same IP address pool without
stepping on each other?  Or if one fails, can the other one automatically
acquire the address pool of the failed HARC?

Is there a way for the second HARC to be assigned the first HARC's IP
address as a hot standby IP address?

If neither HARC is configured as the owner of a modem card, how does the
NMC determine (or is configured to specify) which HARC does route for a
particular modem card?

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From: Jeff Mcadams <[email-masked]>
Date: Thu, 25 Jan 2001 02:57:30 +0000

Also sprach Antonio Querubin

>One problem I've run into is the IP address pools that the HARCs use.
>Is there a way for both HiPer ARCs to share the same IP address pool
>without stepping on each other?  Or if one fails, can the other one
>automatically acquire the address pool of the failed HARC?

Sort of.  The best solution I've found is to set the Arcs to not pick IP
addresses out of their pools by round robin and let them pick first
available.  Default is round robin.

disable ip address_pool_round_robin

Then you can setup two seperate pools on the Arcs for each to serve half
the modems.  Once those are set up, then for each Arc, you configure the
*other* Arcs address pool in it.  So, Arc A has address pool 1 then
address pool 2 list, then Arc B has address pool 2 then address pool 1
listed.  Follow?  Since the pools are the same size, each Arc, in normal
operation will only use the first pool, if the second Arc fails, then,
when dynamic slot assignment rebalancing assigns the modems to the still
good Arc, it will have the other pool of addresses, that the failed Arc
was previously using, available to assign to the newly picked up modems.

>address as a hot standby IP address?

I'm not aware of any way to do this, but with dynamic routing protocols,
the benefit of this is limited.

>If neither HARC is configured as the owner of a modem card, how does
>the NMC determine (or is configured to specify) which HARC does route
>for a particular modem card?

If you have dynamic slot assignment and dynamic slot assignment idle
rebalancing enabled, then, given enough time, the modem cards will
alternate between the Arcs for ownership.
-- 
Jeff McAdams                            Email: [email-masked]
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456

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From: Aaron Nabil <[email-masked]>
Date: Thu, 25 Jan 2001 19:45:40 +0000

> failover.  I'm running into several issues.

It may not work at all.  From the TC4.0 HiperArc release notes...

MR 12602 Issue  Dual HiPer ARC Fail-over not working. When using
two HiPer ARCs, and one is pulled, the other fails to take
ownership of the pulled ARCs HDMs.
Status  No Workaround currently exists

--
Aaron Nabil

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From: Jonathan Byrne <[email-masked]>
Date: Tue, 06 Feb 2001 12:09:30 +0000

It does work for me.  I set it up so that one HARC owns all the
cards and they are statically set.  The backup is set to
owner=no for all slots, but is dynamic.  If the first HARC fails,
the second one then comes in (not immediately, but it does come in)
when the NMC notices the first one is gone and dynamically assigns
all slots to the second one.  

Under normal operation, the second one is just sitting there, and
I assign it the same IP pool as the primary HARC in the chassis.

I've had this work in my test chassis, in a live controlled
experiment where I had to shut down a chassis for other reasons
so I pulled the primary HARC first to see if failover would work
(it did; then I powered off the chassis), and once in an actual
failure.  That one was kind of rocky, though; the primary HARC
failed, but tried several times to ressurect itself and take back
control of the chassis.  This didn't work, but was enough to 
disrupt the chassis several more times.  Naturally, this happened
while I was on vacation, and at a remote POP, not our Tokyo
hub.  By the time somebody got out there to remove the
failed card, it had bounced up and down several times.

It appears that failover will work fine in the even of complete
failure, but if a HARC keeps coming up with "I'm not dead
yet!" then your customers on that chassis can be in for a rough
ride until someone dispatches it.

Jonathan Byrne, CCNA                            Engineering Division
<Large Hosting/Colo company with no public opinions>
Tel:  +81 3-5358-5291                           Fax: +81 3-5358-5306

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From: [email-masked]
Date: Fri, 23 Feb 2001 06:43:32 +0000

Running PRIs on hiperDSPs with a hiperarc, we have discovered a very very
strange thing.  It seems that if we "busy out" any of the channels on
the PRI in TCM, the telco give the famous "The number you have reached,
X X X - X X X X has been disconnected"  ????  I've got limited data, I
admit, because we naturally don't want this happening much.  But anyone
have any thoughts about this?  I'm very surprised that there's anything we
can do on our end that would make the telco give that message.

Thanks in advance!

David

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From: [email-masked]
Date: Sun, 25 Feb 2001 00:18:53 +0000

> can do on our end that would make the telco give that message.

What's the NPANXX of your dial-in pool?

-a

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