ip broadcast address

Unanswered Question
Jan 15th, 2009
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Dear Netpro,

I am curious to the usage of ip broadcast-address. I have a loopback address defined, e.g

interface Loopback0

ip address

ip broadcast-address


However, when the NMS do a snmpwalk to this loopback, the router is able to receive and reply back, but to the NMS, it just time out.

Extract from router's log:

Jan 15 17:07:09.827 UTC: SNMP: Packet received via UDP from on Fast


Jan 15 17:07:09.831 UTC: SNMP: Get request, reqid 217043, errstat 0, erridx 0


Jan 15 17:07:09.843 UTC: SNMP: Response, reqid 217043, errstat 0, erridx 0

sysUpTime.0 = 4078928607

Jan 15 17:07:09.851 UTC: SNMP: Packet sent via UDP to

The way to solve this issue is to remove the ip broadcast-address from the loopback 0.

Any one able to shed some light in this area?



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Overall Rating: 2 (1 ratings)
Tshi M Thu, 01/15/2009 - 07:15
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Loopback is used on devices because it is an interface that never goes down. However, I don't know if this is the answer but I would not use ip broadcast-address on the loopback address since it is a /32 host.


benson.low Fri, 01/16/2009 - 01:10
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my problem starts with the use of command ip broadcast-address. If it is removed, the NMS is able to do a snmpwalk to the loopback address. Otherwise, only snmpwalk of physical ip addresses are possible. This is weird as I do not see this sympton before.


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