EIGRP

[saidfrh]

Hi,

In the EIGRP network statement, is the classless network or classfull network advertised?

router eigrp 100

network 192.168.50.0 or 192.168.50.4 ?

Above interfaces are /30, 255.255.255.252

Thanks.

[Richard Burts]

Said

The answer depends on details of how you configure EIGRP. If you configure it like this:

router eigrp 100

network 192.168.50.0

then EIGRP will look for every interface on the router which is in 192.168.50.0 and include that interface into EIGRP processing.

If you configure it like this:

router eigrp 100

network 192.168.50.4 0.0.0.3

then EIGRP will look for the interface that matches the address and mask and will find at most one interface that matches and that interface will be included into EIGRP processing.

HTH

Rick

[saidfrh]

Rick,

What does 0.0.0.3 mean/reflect in "network 192.168.50.4 0.0.0.3" ?

Thanks.

Said

[Richard Burts · Accepted solution]

Said

the 0.0.0.3 is a mask (actually it is the inverse of the 255.255.255.252 mask) which EIGRP uses to determine which bits must match in selecting interfaces. The original implementation of EIGRP did not use masks in the network statement and any interface that matches the classful network would be included into EIGRP processing. Recent versions of IOS do have the capability of using a mask to match only specific interfaces.

HTH

Rick

[saidfrh]

Rick,

Thanks much for the explanation.

Said