Subject: questions about the vrrp draft

From: Cristina Radulescu-Banu <[email-masked]>
Date: Sun, 5 Apr 1998 20:59:53 -0400

I'm sorry I didn't ask these questions at the meeting, but I
needed to catch my flight while the patent discussion was still going on:

1. The reason for the existence of this draft is to eliminate the
overload of using routing (snooping) a dynamic routing protocol (like
ICMP router discovery, OSPF) in end-hosts. However, VRRP *is* such a
dynamic-discovery protocol, to which you add the statically configured
route to get to the Virtual Router(s) which the end-host wants to use.
Again, if it's only 1 Virtual Router the end-host knows about, you get
back to the problem of having 1 default gateway in the statically
configured route scenario. So I don't see (yet) the point of this 
protocol to be used, instead of ICMP router discovery, for example.

2. At page 12, Section "Priority" in the phrase
"The priority field specifies the sending VRRP router's priority"
I don't know what's the significance of the word "sending" is, since
we speak only about senders here (I think you don't need this word
here, it's redundant).

3. What is the primary IP addr of the iface? (src addr for the IP pkt)
(is the primary interface chosen by the administrator?)

4. Is the Startup Event *always* associated with the router first
coming up in the network? Or are there other instances which
trigger the Starup Event (changes in its own Priority, etc)?

-- 

...............................................................................
Cristina Radulescu-Banu : Midnight Networks 200 Fifth Avenue Waltham MA 02154
[email-masked]  : Vox 781/890-1001 Fax 0028 The Best in Network Software
	
      A conclusion is the place where you got tired of thinking.

---

From: Acee Lindem <[email-masked]>
Date: Sun, 5 Apr 1998 22:35:43 -0400 (EDT)

> needed to catch my flight while the patent discussion was still going on:

I wasn't able to attend but I think I can answer your questions.

> protocol to be used, instead of ICMP router discovery, for example.

The whole point of the protocol is to provide a backup mechanism which
is completely transparent to the hosts. With ICMP router discovery, the 
hosts must take an active role.

> we speak only about senders here (I think you don't need this word

Ok - seems like a nit.

> (is the primary interface chosen by the administrator?)

VRRP advertisements are multicast and can contain multiple addresses.
Hence, a single instance of a Virtual Router can service mulitple IP
subnets on the same physical network. The primary address is the
only configured IP address or an implementation-dependent choice 
of one of the configured IP addresses (e.g,, the first configured). 

> trigger the Starup Event (changes in its own Priority, etc)?

Dynamic configuration of VRRP for the interface could start 
VRRP without a network-up event. Also, if you look at the MIB
draft I believe there are write-capable variables which will effect
VRRP's status.