From: ccie2be (ccie2be@nyc.rr.com)
Date: Sat Mar 26 2005 - 09:15:14 GMT-3
Hi Mani,
The fact that you're thinking about these issues puts you a step ahead.
The answers to your question depend a great deal on the actual wording of
the task.
But, here are some things to get in mind.
If the workstations on the segment must seamlessly switch over to a
different router in case of failure, that rules out some potential configs,
for example, using the dhcp command, default-gateway <r1> <r2>, because
Windows based hosts don't accept more than one default gateway at a time.
I'm not sure of their exact behavior but suffice it to say that HSRP or some
equivalent functionality is required.
I don't know of any link that compares the functionality of HSRP vs VRRP vs
GLBP so it's up to you to do the comparison and know enough about their
similarities and differences to make an informed decision on which to
choose. Again, depending on the exact wording of the task, it might not
matter which of these you configure in which case you can choose the one
that's easiest to config.
As for IRDP, I think (but haven't looked at this in a while) that this is
NOT supported by Win based hosts which means that these hosts wouldn't
seamlessly switchover to a different router if the current default gateway
fails.
One clue you might be given would be something to the effect that if a
router interface which isn't on the lan segment fails, use the other router.
In this case, you obviously have to track the state of 1 or more interfaces
which means you have to config HSRP or VRRP or maybe GLBP (I can't remember
if GLBP tracks interfaces states).
Also, be aware of a new 12.2T feature called Enhanced Object Tracking. This
allows other things besides interface state to be tracked e.g. entries in
the route table??? (Again, it's been too long since I read about it to
remember the details but if the decision of which gateway to use has to be
made based on something other than interface state, it's probable that EOT
is being called for.
HTH, Tim
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of mani
poopal
Sent: Friday, March 25, 2005 6:24 PM
To: ccielab@groupstudy.com
Subject: DHCP/HSRP/VRRP/IRDP
Hi Group,
I have some doubts about these features. So lets assume R1 and R2 connected
by ethernet link(vlan 10).
R1 e0 ----------------150.50.5.0/24---VLAN 10 ---------------------e 0 R2
(1.)-A If question asks for vlan 10 users should prefer R1 and if not
available R2
If nothing specified, what is a good solution, hsrp, vrrp or irdp. If we
were to use hsrp or vrrp, what ip address to configured to use for virtual
ip address(eg: stanby 1 ip x.y.z.k). Can we assume any arbitary address in
the vlan 10 range.
(1)-B for the same question as above, if there is a switch without routing
enabled, if you need access from switch to rest of the network, in the ip
default-gateway x.x.x.x, what is the ip to be used R1 eo or R2 e0 or virtual
ip address(If vrrp or hsrp is used)
(2.)The same scenario, if they ask not to use hsrp, what is the best method
to use, vrrp or irdp.
(3.)The same scenario, if they ask to configure DHCP on R2 and for
redundency not to use HSRP. What we will use, is it VRRP or IRDP, if it is
IRDP do we define a defalt-router in the dhcp configuration.
(4.)So how do we determine the best method(out of hsrp, vrrp, irdp) if we
were to use hsrp or vrrp and if the virutal ip adress is not given, do we
have to select an arbitary adddress(in the range of vlan) for virtual ip
address. Does vrrp support interface tracking feature and if what is the
command and mode.
(5.)If we were to use irdp, how the question can be phrased, clues for key
word
(6.)If anybody can send me an URL for exact differences for these features
it will be great
again thanks in advance
Mani
B.ENG,A+,CCNA,CCNP,CCNP-VOICE, CSS1,CNA,MCSE
(416)431 9929
MANI_CCIE@YAHOO.COM
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