From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Jun 13 2007 - 12:51:44 ART
The DR/BDR election must take some measurable time, even if it
is in the order of milliseconds for your platform. Running the link as
point-to-point network type would eliminate this unnecessary exchange.
Whether you will see an effective difference or not is hard to say, but
if you're looking for the highest availability possible then even if the
election takes only 5ms it can't hurt to disable it.
HTH,
Brian McGahan, CCIE #8593 (R&S/SP)
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Geert Nijs
Sent: Wednesday, June 13, 2007 2:27 AM
To: ccielab@groupstudy.com
Subject: Fastest OSPF neighbor up on a link
Hello all,
I am looking for the fastest possible neighbor up time on a simple p-t-p
fiber link between switches:
SW1(core) ------- fiber ------ SW2
The link is configured as a Layer3 link and has a /31 subnet mask.
However, by default, OSPF uses the broadcast network type for this link,
and therefore starts DR/BDR elections.
I now have the following options, i want the fastest possible "neighbor
up" or "neighbor down".
Does Cisco have any recommendation regarding this ?
1) core switch is forced DR, edge switch is forced BDR
SW2
interface GigabitEthernet1/0/28
no switchport
ip address 10.56.158.11 255.255.255.254
ip ospf dead-interval minimal hello-multiplier 4
ip ospf priority 1
carrier-delay msec 0
SW1
interface GigabitEthernet1/0/28
no switchport
ip address 10.56.158.11 255.255.255.254
ip ospf dead-interval minimal hello-multiplier 4
ip ospf priority 255
carrier-delay msec 0
2) core switch is forced DR, edge switch is forced DROTHER
SW2
interface GigabitEthernet1/0/28
no switchport
ip address 10.56.158.11 255.255.255.254
ip ospf dead-interval minimal hello-multiplier 4
ip ospf priority 0
carrier-delay msec 0
SW1
interface GigabitEthernet1/0/28
no switchport
ip address 10.56.158.11 255.255.255.254
ip ospf dead-interval minimal hello-multiplier 4
ip ospf priority 255
carrier-delay msec 0
3) completely eliminate DR/BDR election and put interface in p-t-p mode
SW2
interface GigabitEthernet1/0/28
no switchport
ip address 10.56.158.11 255.255.255.254
ip ospf dead-interval minimal hello-multiplier 4
ip ospf network point-to-point
carrier-delay msec 0
SW1
interface GigabitEthernet1/0/28
no switchport
ip address 10.56.158.11 255.255.255.254
ip ospf dead-interval minimal hello-multiplier 4
ip ospf network point-to-point
carrier-delay msec 0
regards,
Geert
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