I was told this in another venue:
>It is the nature of HSRP. Both routers listen to broadcast traffic.
Both
>routers are configured as a DHCP and BOOTP relay agent in order to get
>redundancy. So all DHCP and BOOTP broadcast traffic is sent twice to
the
>central server.
Is there some reason for this to be true?
It does not seem right to me.
My understanding is that, normally, HSRP does not depend on multiple
routers in the group to forward traffic. The HSRP group appears as one
router to the side where it is being redundant, with the primary router
forwarding all traffic. The standby doesn't participate, except
possibly
on reply traffic
I think that you would agree that it is not normal nor good (maybe not
necessarily bad, but certainly not good :) for a router arbitrarily to
send duplicate packets onto a subnet and this is, in effect, what would
be happening here.
In single-group HSRP mode, I can see no reason for this to be
required --
I would think that it would be sufficient for the UDP forwarding simply
to follow the primary router.
Multi-group HSRP seems to present some other possibilities/problems that
I haven't explored in depth yet. One point is that it would appear that
having MHSRP primary routers forwarding DHCP (at least the broadcasts)
would require extraordinary configuration on the DHCP server. For
example, if the clients are in the same subnet, then which default
gateway should it send to the client? Thus, MHSRP *with* DHCP
forwarding
would seem to require, practically, multiple subnets and broadcast
domains -- i.e., VLANs.
Comments?
-------------------------------------------------
Tks | <mailto:[EMAIL PROTECTED]>
BV | <mailto:[EMAIL PROTECTED]>
Sr. Technical Consultant, SBM, A Gates/Arrow Co.
Vox 770-623-3430 11455 Lakefield Dr.
Fax 770-623-3429 Duluth, GA 30097-1511
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