ip broadcast address

benson.low · ‎01-15-2009

Dear Netpro,

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

interface Loopback0

ip address 1.2.24.70 255.255.255.255

ip broadcast-address 1.2.24.70

!

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 1.8.28.5 on Fast

Ethernet0/0

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

sysUpTime.0 = NULL TYPE/VALUE

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 1.8.28.5

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?

Rgrds,

Benson

Tshi M · ‎01-15-2009

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.

Regards,

benson.low · ‎01-16-2009

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.