Re: Default Value of Accept_Mode

Hi Mukesh,

 

There are no interoperability issues w.r.t to the VRRP state machine.
The interoperability

issue that I mentioned refers to network deployments where customers
have devices

from different vendors on their network and each vendor has a different
default value. In

such situation, the onus is on the customers to know the default value
for each implementation

and set it accordingly, which I think is not a good idea. Let us choose
a default value for all

implementations. If the customer wants to change it, they can change it
for all devices in the

network. I believe, the concern is should it be TRUE or FALSE. With VRRP
for IPv4, this option

did not exists.  Accept_mode is now being introduced for the unified
spec. If there are

no security/vulnerability issues w.r.t. accepting packets address to the
virtual IP address, then

let us default the value to TRUE.

 

Here is a crude analogy - can the VRRP hello timer value be a default
value per implementation?

 

John

 

From: Mukesh Gupta [mailto:[email protected]] 
Sent: Tuesday, October 06, 2009 9:53 AM
To: John Cruz (johcruz); [email protected]
Cc: [email protected]; Adrian Farrel
Subject: RE: [VRRP] Default Value of Accept_Mode

 

John,

 

Could you please explain a little more about the interoperability issues
that you are referring to?

 

As far as I understand, an operator will see different behavior from the
devices with different default values when he/she tries to connect to
the virtual address.  However, it should not cause any protocol
interoperability issues.  Moreover, the operator would be able to change
the default value using the configurable knob to see consistent behavior
from all the devices.

 

Regards

Mukesh

 

From: John Cruz (johcruz) [mailto:[email protected]] 
Sent: Monday, October 05, 2009 11:49 AM
To: Mukesh Gupta; [email protected]
Cc: [email protected]; Adrian Farrel
Subject: RE: [VRRP] Default Value of Accept_Mode

 

Hi Mukesh,

 

Leaving the default value to be implementation

dependent may not be a good idea as it will cause

interoperability issues in environments where

customers  have a mix of devices from different

vendors.

 

John

 

From: [email protected] [mailto:[email protected]] On Behalf Of
Mukesh Gupta
Sent: Friday, October 02, 2009 4:26 PM
To: [email protected]
Cc: [email protected]; Adrian Farrel
Subject: [VRRP] Default Value of Accept_Mode

 

[WG Chair Hat Off]

 

Folks,

 

During the IESG review of the unified VRRP draft, Dan, Operations and
Management AD, questioned the default value of the Accept_Mode in the
draft.  The current default value is False and he would like us to
reconsider that (his comments in the end of this email).

 

We had discussions about this on the mailing list.  However, I don't
remember having a clear WG consensus for either default value.

 

Given the fact that the default value has absolutely no impact on the
interoperability and the fact that both the values have their pros and
cons, we are proposing that the draft should leave the default value to
the implementations.  The draft would say that the implementations are
free to choose any default value.

 

Please let us know if you agree/disagree.  If we do not hear anything
back, we will assume that the WG agrees J

 

Regards

Mukesh

 

Dan's  Comment:

=============

3. Accept_Mode defaulting to false seems unrealistic at least in
deployments

I've seen.  Using accept-data config knob seems very common. Unless
enable

Accept_Mode, when the virtual address moves to the Backup, the virtual
address

no longer responds to ping; I've also seen an implementation to reject
pings to

the virtual IP when it's in Master mode, but this seems like an
implementation

bug if so (I'd like a confirmation if this is the case).

 

In any case, this restriction makes troubleshooting and deployment a
pain; hosts

and management systems often ping the gateway address to see if the
network is

working, and this kills that assumption.

 

Unless the WG has recently discussed and reached consensus that
Accept_Mode

should still default to false, I'd consider revisiting this position.

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