Subject: (ION) How do a NHS discovery its neighbour?

From: "Zhu Guoping" <[email-masked]>
Date: Wed, 10 Feb 1999 11:35:13 +0800

Hello,Everyone! 
I have a question to ask you.How do a NHS discovery it's = 
neighbour?When a NHS in a router need to send a NHRP request to the NHS = 
in the next router,How do the NHS get the ATM address of the next NHS = 
in the next hop router?It seems 
that there is no discuss about this in RFC2332. 
If anyone know this, please tell me.Thanks in advance.
Best regards.

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From: "Albert Manfredi" <[email-masked]>
Date: Wed, 10 Feb 1999 10:43:28 -0500

Think of the NHSs as simple IP routers. How do IP routers know the
next router to go to? They know because they have a routing protocol
(e.g. OSPF or RIP) operating in the background, keeping routing
tables up to date.

NHRP requests and NHRP replies travel along the standard old IP
routed path. No problem, unless you reach the edge of the ATM cloud
before reaching the destination host itself (e.g. the destination
host is in another ATM cloud, or is not an ATM-connected device.

If this happens, if the destination host itself is not directly
reachable with an NHRP request, the NHRP request will stop at that
edge NHS/router, and the reply will be the ATM address of that edge
NHS. So the shortcut will get as close as possible to the
destination IP host within that ATM cloud.

Bert
[email-masked]

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From: "Albert Manfredi" <[email-masked]>
Date: Fri, 12 Feb 1999 10:36:21 -0500

-----Original Message-----
From: Navin Kumar Agarwal <[email-masked]>

>Hi,
>
>> NHS do not "discover" their neighbors.  Their neighbors are
routing
>> peers.  As such, before the NHS could want to send an NHRP
message
>> (request or response), it must have routing knowledge of that
neighbor.
>> The techniques for determining the ATM address for the NHRP are
the same
>> as those used for determining the ATM address for sending a data
packet
>> to that neighbor.  [These techniques include static
configuration,
>> anycast, ILMI, PAR, and others.]
>
> Are you saying that the methods you have mentioned can be
>directly used to determine the ATM address of the next hop NHS? Or
the
>methods (ILMI, anycast) in turn will help an NHS in getting the ATM
>address of the ATMARP server for that particular LIS, And finally
the
>ATMARP server will resolve the ATM address of the next hop NHS??

ILMI allows you to request information on objects you specify. See
Section 10 of ILMI 4.0, Service Registry MIB.

Use of anycast is more direct. Anycast addresses would be defined
specifically for services such as NHS or ATMARP, and depending how
the netywork is set up, PNNI would get you to the topologically
closest server to you that responds to the anycast address.

Bert