Subject: RE: [VRRP] GARP in draft-ietf-vrrp-spec-v2-10.txt

From: "Renwei Li" <[email-masked]>
Date: Thu, 22 Apr 2004 10:21:48 -0700

There is no puzzlement in your diagram!

In your diagram, the virtual MAC is still (and always) calculated from
the VRID. It is pretty much normal that different IP addresses are
mapped to the same MAC. Note that MAC is used for L2 encapsulation, but
not for IP forwarding.  When forwarding an IP packet, the host/router
needs to find out the next-hop interface, next-hop IP address, etc from
its routing table. After the next-hop IP address (in this diagram, it
will be either IP-A or IP-C)is found, the MAC address is used for the
encapsulation in the L2 header, and then the IP packet is forwarded out
of the next-hop interface.

Hope it helps.

Regards,

Renwei

> -----Original Message-----
> From: William StanisLaus [mailto:[email-masked]] 
> Sent: Wednesday, April 21, 2004 11:50 PM
> To: Renwei Li; [email-masked]
> Subject: RE: [VRRP] GARP in draft-ietf-vrrp-spec-v2-10.txt
> 
> 
> Thanks for all :)
> 
> but this reponse puzzles me ;)
> 
> what if ??
> 
>  +-------+   +-------+         +-------+   +-------+
>  | Rtr1  |   | Rtr2  |         | Rtr3  |   | Rtr4  |
>  |(MR    |   |(BR    |         |(MR    |   |(BR    |
>  |VRID=1)|   |VRID=1 |         |VRID=1)|   |VRID=1 |
>  +-------+   +-------+         +-------+   +-------+
>  ---->*        *<- IP B      IP C->*       *<- IP D
>  IP A |        |                   |       |
>       |        |(Subnet 1)         |       |(Subnet 2)
>  -----+--------+---------+      ---+----+--+-----+--
>       ^        ^         |              ^        ^
>       |        |         |              |        |
>     (IP A)   (IP A)      |            (IP C)   (IP C)
>       |        |         |              |        |
>    +--+--+  +--+--+      |          +--+--+  +--+--+
>    |  H1 |  |  H2 |      +----------|  H3 |  |  H4 |
>    +-----+  +-----+         (IP A)  +--+--+  +--+--+ 
> 
> 
> This is case, i assume VMAC calculation from VRID also 
> consider's VRIP or physical IP address.
> 
> otherwise, H3 will have same MAC configuration for both IP A and IP C
> 
> Best Regards,
> William.
> 
> 
> 
> 
> 
> > -----Original Message-----
> > From: Renwei Li [mailto:[email-masked]]
> > Sent: Thursday, April 22, 2004 5:48 AM
> > To: [email-masked]; [email-masked]
> > Subject: RE: [VRRP] GARP in draft-ietf-vrrp-spec-v2-10.txt
> > 
> > 
> > 
> > 
> > > 
> > > first place. I beleive the virtual MAC is calculated from the
> > > Virtual IP address, something similar to Multicast MAC 
> > > calculation form multicast address.
> > > 
> > 
> > Wrong.
> > 
> > The virtual MAC is calculated from the configured VRRP VRID.
> >  
> > 
> > Regards,
> > 
> > Renwei
> > 
> 

_______________________________________________
vrrp mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/vrrp