Virtual Router Redundancy Protocol (vrrp)

Stephen Nadas | 14 Oct 2010 18:10

Re: RFC5798

IMO better to ask VRRP list than me, individually,

Regards,

Steve

From: Carl Petersen [mailto:CPetersen <at> broadsoft.com]
Sent: Thursday, October 14, 2010 11:13 AM
To: Stephen Nadas
Subject: RFC5798

Stephen, I want to ask you a question about this RFC and the VRRP protocol. Regarding section 6.4.3, bullet points (735) to (765).

If 2 vrrp routers became isolated for whatever reason, one router would remain as master, the other would transition from backup to master and send a gratuitous arp (ipv4 only) to notify remote arp caches. My question is about when the fault is corrected. One router transitions from master to backup; the other router still remains as master. The backup router follows (735) to (765), but the master seemingly does nothing at all. In particular the now-for-real master does not send a gratuitous arp. This leaves remote arp caches with the wrong ip/mac value.

I’m sure this has been considered. What is typically done to prevent this scenario or to recover from it?

Thanks

Carl Petersen

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Danny J. Mitzel | 14 Oct 2010 18:53

Re: RFC5798

When VRRP is enabled then the associated MAC address is always

fixed 00-00-5E-00-01-{VRID}. Whether there's a Master failover, or

network partition and heal, etc. there's no change to the mapping and

all client hosts should be consistent. No action is required.

The sole reason for the gratuitous ARP is to increase robustness

the very first time VRRP is enabled in the network. Prior to VRRP

enable some client hosts may have cached the router physical

MAC address. When VRRP is then enabled the first Master

transition triggers gratuitous ARP to encourage client hosts to

flush the router physical MAC address if it's in their cache.

--- On Thu, 10/14/10, Stephen Nadas <stephen.nadas <at> ericsson.com> wrote:

From: Stephen Nadas <stephen.nadas <at> ericsson.com>
Subject: Re: [VRRP] RFC5798
To: "Carl Petersen" <CPetersen <at> broadsoft.com>
Cc: "vrrp <at> ietf.org" <vrrp <at> ietf.org>
Date: Thursday, October 14, 2010, 9:10 AM

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IMO better to ask VRRP list than me, individually,

Regards,

Steve

From: Carl Petersen [mailto:CPetersen <at> broadsoft.com]
Sent: Thursday, October 14, 2010 11:13 AM
To: Stephen Nadas
Subject: RFC5798

Stephen, I want to ask you a question about this RFC and the VRRP protocol. Regarding section 6.4.3, bullet points (735) to (765).

If 2 vrrp routers became isolated for whatever reason, one router would remain as master, the other would transition from backup to master and send a gratuitous arp (ipv4 only) to notify remote arp caches. My question is about when the fault is corrected. One router transitions from master to backup; the other router still remains as master. The backup router follows (735) to (765), but the master seemingly does nothing at all. In particular the now-for-real master does not send a gratuitous arp. This leaves remote arp caches with the wrong ip/mac value.

I’m sure this has been considered. What is typically done to prevent this scenario or to recover from it?

Thanks

Carl Petersen

-----Inline Attachment Follows-----

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https://www.ietf.org/mailman/listinfo/vrrp

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Mahesh Kelkar | 22 Oct 2010 17:14

Any examples of using VRRP in systems/solutions other than Routers?

Hello,

Since VRRP is designed to eliminate single point failure, I was
wondering if VRRP is used on systems/solutions that do not involve
routers.

Are there any examples of such usage?
Are there any known real world deployments?
Are they recommended?

I came across some discussions on using VRRP as a failover protocol
for Linux Virtual Server (LVS). But I don't know if its deployed or
not..

Thanks
Mahesh
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Martin Visser | 24 Oct 2010 12:47

Re: Any examples of using VRRP in systems/solutions other than Routers?

I think you will find it is used a lot on devices employing high availability functions (HA). For instance I know for sure that Nortel's Switched Firewalls and Alteon Load Balancer's use VRRP to implement shared addresses across HA pairs. I am pretty sure many such appliances use it in this fashion just Googling for seemed to show that Citrix Netscalers and Juniper Netscreen use it such a fashion

Regards, Martin

MartinVisser99 <at> gmail.com

On Sat, Oct 23, 2010 at 2:14 AM, Mahesh Kelkar <maheshkelkar <at> gmail.com> wrote:

Hello,

Since VRRP is designed to eliminate single point failure, I was
wondering if VRRP is used on systems/solutions that do not involve
routers.

Are there any examples of such usage?
Are there any known real world deployments?
Are they recommended?

I came across some discussions on using VRRP as a failover protocol
for Linux Virtual Server (LVS). But I don't know if its deployed or
not..

Thanks
Mahesh
_______________________________________________
vrrp mailing list
vrrp <at> ietf.org
https://www.ietf.org/mailman/listinfo/vrrp

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https://www.ietf.org/mailman/listinfo/vrrp

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