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331
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BGP

The_guroo_2
Level 2
Level 2

‎04-22-2008 09:39 PM - edited ‎03-03-2019 09:39 PM

guys when we config loopback addresses i have seen we normally use /32 mask like 1.1.1.1 255.255.255.255 why not normal mask....thanks in advance

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mohammedmahmoud
Level 11
Level 11

‎04-22-2008 11:34 PM

Hi,

A simple answer would be that the loopback interface is a logical interface, with no adjacent interfaces on the same subnet (no connected interfaces on its data-link), and thus no mean for using more than a /32 for it.

BR,

Mohammed Mahmoud.

Giuseppe Larosa
Hall of Fame
Hall of Fame
In response to mohammedmahmoud

‎04-23-2008 04:15 AM

Hello,

one case when a network mask different from /32 could be used is when the loopback is used to advertise a nat pool of addresses in a routing protocol.

In a MPLS environment a /32 is mandatory because the loopback address is the node identifier for MPLS TE

best regards

Giuseppe

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cisco_lad2004
Level 5
Level 5

‎04-23-2008 05:39 AM

I second Giusessepe with regards to MPLS, and add that you also want to save ip addresses even the private ones.

HTH

Sam

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