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| ZacDogg 2002-04-10, 9:28 am |
| I've just read that, if the priorities are the same then the active router is elected by the highest IP address,(which is what I've always thought.) I also just read that if the active and standby routers both fail, the rest of the routers in the standby group contend for active and standby status and the one with the lowest MAC address ??? becomes the active router.
My question is why wouldn't the priorites, then the IP address be consulted to elect the active and standby routers? Why because the active and standby fail is there a different way to elect? | |
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| ZacDogg 2002-04-10, 9:58 am |
| Thank you for your response, but your answer didn't really help. I am reading in a Cisco Press book that if both the active and stanby routers fail, the router with the lowest MAC address from the remaining routers in the standby group is elected the active router. Is this correct, and if so could someone tell me why. | |
| ZacDogg 2002-04-10, 10:10 am |
| Thank you for your response, but your answer didn't really help. I am reading in a Cisco Press book that if both the active and stanby routers fail, the router with the lowest MAC address from the remaining routers in the standby group is elected the active router. Is this correct, and if so could someone tell me why. | |
| darthfeces 2002-04-10, 10:14 am |
| your question does not actually make sense ?
isn't it logical that if your active and standby fail that what's left (if configured) would take over ?
if it's still unclear search out the technical documents on cisco's site describing the individual protocall's operation.
we personally have 2 mffc's using hsrp
with the virtual being .1 of each net and .2 .3 the actual interface address.
this never fails and if we lost both core's
the network would be so crippled that it would
not matter anyway.
i'd get used to searching the cisco site
and become used to answering your own questions
instead of looking for them to be answered.
http://www.cisco.com/univercd/home/home.htm
end rant | |
| tan.phan 2002-04-10, 4:32 pm |
| quote:
Originally posted by darthfeces
your question does not actually make sense ?
i'd get used to searching the cisco site
and become used to answering your own questions
instead of looking for them to be answered.
http://www.cisco.com/univercd/home/home.htm
end rant
^
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Agreed to both.
But to help ZacDogg...maybe a scenario would clear thing up a little.
Let say you have a VTP domain consists of 20 subnets. Your core is running HSRP between two core routers A & B.
On router A you configured the first 10 networks or HSRP group to be in Active (higher priority) and the last 10 networks (groups) to be in Standby (lower priority).
On router B you configured the first 10 networks to be in Standby while the last 10 to be in Active.
Why should the configuration be this way? why half and half...why dont we just configured router A to have 20 networks in Active, and router B all in Standby? Well we could do it this way...but this would give us no "Load balancing" which is important.
With the 50/50 configuration you have full redundancy and load balancing between router A & B. Both router A & B forward traffic using the Active group.
If router A should failed, the 10 Standby groups on router B will become Active. Vice versa if router B should failed. If both routers failed then you are pretty much SOL.
Unless...you have another pair of routers that also run HSRP that interconnected to the existing HSRP routers. But this usually not a feasible design...because of COST vs. AVAILABILITY factor.
Interesting issue arise tho...what if 2 HSRP group have equal priority? What metric(s) is used to determine who will be Active or Standby. Is this what you most interested in?
If I have time tomorrow...I will try to simulated this in the lab and find out.
Peace!
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| darthfeces 2002-04-10, 10:36 pm |
| thanks,
for the pick me up
stressing over cissp and lab prep ! | |
| ZacDogg 2002-04-11, 5:26 am |
| tan.phan,
Yes, this is what I was the most interested in. I just found it odd that the Cisco Press book I was reading stated that lowest MAC would be the determining factor in the event both the A & S routers fail (maybe it has to do with the A & S's proirities and IP's still being higher, so you need to get them out of the equation by going to a diff. determining factor?). I understand this configuration is normally not the case. Not a situation one would run into often. Just something I was curious about.
And Darth, I did search Cisco's site for some time. Couldn't find anything, so I thought I would pose the question here. That is what this forum is for isn't it??? | |
| tan.phan 2002-04-11, 3:55 pm |
| Well, my conclusion is HSRP doesn't care about IP or MAC as determine factor when 2 groups has equal priorities. You may not agreed but after 3 hrs of messing around that was what I came up with.
To have this prooved two 2610 routers were connected thru a switch, the routers were then configured with 2 HSRP groups both groups has default priority of 100, one group has ip of 10.0.0.3/24 while the other group has an ip of 10.0.0.240/24.
Then...
Both routers were power off.
Router with 10.0.0.3 address was booted first...it then become the Active.
Router with 10.0.0.240 address was then booted last...it become Standby.
If ip was the decide factor in case of equal priority then the 10.0.0.240 router should take Active status as soon as he come on line. Agreed!
As for MAC address...I don't know.
See log.txt...it may shine some light...
Peace! |
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