To add further...
As Nigel pointed out, HSRP has nothing to do with
routing protocols unless you're on token ring - see my
last note for more info on this limitation.
A lot of folks are confused on how HSRP actually works
so heres the low down.
HSRP only works on LAN interfaces. It is meant to
provide a redundant 'default-gateway' for end hosts.
HSRP adds a Virtual IP address (standby group) to the
interface/segment/VLAN/whatever. The interface's real
IP address is still up and functioning as normal.
(The standby routers interface is not in a down state
- just the virtual IP is not active). All packets
sourced from router are sourced with the real IP
address, not the Virtual.
The HSRP Virtual IP address only listens to and
forwards unicast packets sent directly to it. It does
listen to broadcast/multicast traffic. With proxy-arp
the router will respond with the HSRP Virtual MAC
address.
HSRP does have some limitations on Token Ring which
only has 3 functional multicast addresses. For
example, if you had OSPF and HSRP on token ring that
would use 2 of the multicast addresses leaving you
with one left.
Any more questions?
HTH, Erick
--- Nigel Taylor wrote:
> Raina,
> If I'm not mistaken HSRP deals specifically
> will layer 2/3
> redundancy and technically has nothing to do with
> routing. Since the
> routers involved will of course have to be a part of
> a routing domain(ospf ,
> eigrp, mixed).
>
> You should look at RFC 2281, for the specifics...
> http://www.ietf.org/rfc.html
>
> Ask yourself the this well known Howard-ism...after
> reading the RFC.
>
> "What is the problem you're trying to solve..?"
>
> HTH
>
> Nigel
>
>
>
> From: "Tribavan Raina"
> To:
> Sent: Tuesday, September 18, 2001 9:57 PM
> Subject: how does HSRP integrate with OSPF [7:20343]
>
>
> > Hi all..
> >
> >
> > I have 2 routers and I am running HSRP on them.The
> third router is
> connected
> > via a switch through its e0/0 and running OSPF.All
> the routers are running
> > OSPF.
> > What routing tables will the exchange.
> >
> > Regds
> >
> > Tribavan Raina
> > Network Consultant
> >
> > TechTonics Group Limited
> > Level 31 Grand Plimmer Tower
> > 2-6 Gilmer Terrace
> > PO Box 11 199
> > Wellington
> >
> > Ph: +64 4 385 2628
> > Fax: +64 4 385 2400
> >
> > www.techtonics.co.nz
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