From: Stong, Ian C [GMG] (Ian.C.Stong@mail.sprint.com)
Date: Mon Jan 13 2003 - 16:14:04 GMT-3
If the pvc's to the two different head ends have equal costs then I would
let EIGRP equal cost load balance. If the paths are not equal you will have
to manually tweak and as such you will be preferring one path over the
other. So for example if you have two remote sites you can tweak it such
that site A prefers the path to headend router A and site B prefers the path
to headend router B. In the event of a failure they would take the next
feasible successor path. I'm not sure how else you would be able to split
the traffic from each site and place 50% on one path and 50% on the other
path using just EIGRP. You could look at other options perhaps such as
policy based routing, classes and so forth but that would slow packet
processing down somewhat which may or may not be an issue for you.
Just my thoughts.
Ian
www.ccie4u.com
-----Original Message-----
From: Vinay Arora [mailto:cybervinay@yahoo.com]
Sent: Monday, January 13, 2003 2:02 PM
To: Stong, Ian C [GMG]; ccielab@groupstudy.com
Subject: RE: Selecting a preferred route when using EIGRP
I provided the link for reference to EIGRP tweaking and does not depict my
scenario.
The remote sites have only one physical link to frame relay provider and
have 2 PVCs one each to both head ends. Tweaking the EIGRP parameters will
allow to select the PVC circuit I want to use at the remote site.
Since both heads will be talking EIGRP with each others and both will have
routes to all remote sites, how do I designate half of the remote sites to
be active on head-end 1 and remaining half on head-end 2?
Vinay
-----Original Message-----
From: Stong, Ian C [GMG] [mailto:Ian.C.Stong@mail.sprint.com]
Sent: Monday, January 13, 2003 1:51 PM
To: Vinay Arora; ccielab@groupstudy.com
Subject: RE: Selecting a preferred route when using EIGRP
I haven't implemented this in production in awhile since most larger
networks use OSPF or ISIS so take with a grain of salt...
I'm not clear as to your remote sites and whether they will also have
redundant links but will assume not. If you have equal cost paths into your
network you can let EIGRP naturally load balance from the provider to your
network. I'm not sure that the link and configs you provided apply to your
situation. The likelihood is your remote sites will compute the total cost
from end to end and take whichever pipe has the least total cost. You can
influence the paths some by using more than the standard bandwidth and delay
that are used by default but not sure how much that would buy you if the
links turn out to have equal costs. If the costs are not equal than one
will be preferred over the other of course. If you do decide to tweak I
would suggest using the bandwidth and administrative distance options with
care. Try the other options first such as changing the composite metric or
delay values.
Best of luck,
Ian
www.ccie4u.com
Rack Rentals and Scenarios
-----Original Message-----
From: Vinay Arora [mailto:cybervinay@yahoo.com]
Sent: Monday, January 13, 2003 12:55 PM
To: ccielab@groupstudy.com
Subject: Selecting a preferred route when using EIGRP
We have a hub and spoke architecture with all remote sites being connected
to and accessing servers at the central site. EIGRP is the routing protocol
and remote sites need to communicate to central site only and not to each
other.
We will be having two physical frame-relay T1 pipes at central site to the
frame relay provider's cloud. These two will be terminating to different
head end routers at central site. We will be having two PVCs each for remote
locations and these PVCs will terminate on different head-end routers.
I need to make half of the PVC active on first head end and remaining PVC on
second head-end.
When one of the head-end routers goes down the PVC on second should
automatically become active.
I know I will have to do changes to the EIGRP config of routers at remote
locations (EIGRP variables delay, offset, AD, BW etc.)
I am considering the various options for selecting a preferred route when
using EIGRP as detailed in the document at
http://www.cisco.com/warp/public/103/14.shtml#O2
This is a very common scenario and I want to check how people do it
normally? Appreciate any thoughts, ideas and concerns.
TIA
Vinay Arora
.
.
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