Lior,

Firstly, Could you please describe the utilty of such a config?.

Assuming its useful:

Q 2) can be easily commented on: If for some reason we endup having 2 Router-masters for same ip address the host arp cache would continuosly get overwritten with an alternating mac and hence only one of the routers would endup forwarding (though both cld be capable). (Of course your implementation of arp would also determine what you do when you do detect that another router is advertising a mac for an ip which you think you own.)

Q 1)  has some unstated part I think. How will you associate two mac address with same IP address on the same interface of the router? (If you were thinking of two different interfaces, tht is opening up a pandora's box or assuming some capability of the router) Firstly, I donot know the utility of associating two macs with same ip on the same lan segment(What is it?) . But I guess, tht wld determine what behavior u define for your arp when such an association *is* made. This behavior wld then lead to asking 1) or something similar.

This would also help us say if such a vrrp config should be allowed in first place or not (though RFC doesnt speak anything on this config scenario). Probably add a line on this in RFC once this is resolved?

Please comment/correct me if am wrong.

Thanks,

Vikram 

 Lior Ronen <LiorR <at> radlan.com> wrote:

Hello,

 

I wonder if someone can help me decide if the following configuration is allowed:

 

To the same LAN 3 routers (R) are connected :

R1, R2 & R3.

 

R1 has IP address 2.100.100.100.

 

Usually we would configure one VR:

VR = {Owner = R1, Non-Owner = R2, Non-Owner = R3, AssoIpAddr = 2.100.100.100}

 

Are we allowed to configure 2 Virtual Routers (VR):

VR1 = {Owner = R1, Non-Owner = R2, AssoIpAddr = 2.100.100.100}

VR2 = {Owner = R1, Non-Owner = R3, AssoIpAddr = 2.100.100.100}

 

If yes -

1. What about having R1 send two gratuitous arps, in which 2.100.100.100 is once said to have Mac = 00:00:5e:00:01:01 and once said to have Mac = 00:00:5e:00:01:02 ?

2. When R1 breaks down, R2 & R3 will become Master and duplicate forwarding will take place.

 

Should I in my implementation allow only one VR per Associated IP address ?

 

Thank you for your time,

Lior

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Lior Ronen

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