OSPF Router/PIX Differences?

[RoundAbout]

This is really weird...

On my 2620 routers when I configure OSPF, the "network" command wants the network mask similar to this (0.0.0.255) while on my PIX 501's they want the mask in the normal form (255.255.255.0).

Is this correct?

Also, the v6.3 Reference Guide states that OSPF does NOT run on the 501 but it's accepting "router ospf" commands? Very Strange.

Thanks!

RoundAbout

 

[rcasta]

Actually I guess the answer is quite straight forward. When configuring OSPF (and a couple of routing protocols as well as access lists), it is asked to use wildcard masks.
Router(config-router)#network 172.16.1.0 ?
A.B.C.D OSPF wild card bits

Wildcard mask is nothing but turning bits on or off (like applying an XOR) to the binary written mask.
Therefore, when having a subnet mask 255.255.255.0 you really have in binary format subnet 11111111.11111111.11111111.00000000, and when asked to enter wildcard bits, "1" bits are then turned off and "0" bits on. Hence, the wildcard bit mask results in 00000000.00000000.00000000.11111111, which in decimal format is 0.0.0.255

Finally as far as the PIX concerns, I guess it asks you for the normal subnet mask format.

BWY, I can't tell anything about whether the PIX runs OSPF or not. Have no clue...perhaps Cisco forgot to take it off. Does it work? Have you give it a try?

best regards,

 

[RoundAbout]

It's just kinda' strange to have both types of masks when the end result is the same. I think we all pretty much know and understand regular bit masks so why go and throw in the bit-inverted wildcard variety? It just seems... silly.

I don't know if OSPF is working on the 501 yet, I need to set it up on the PIX at the other end of the (VPN) tunnel.

Thanks for the explanation.

RoundAbout

 

[routerman]

OSPF support was introduced in PIX OS 6.3, is that what your running on your 501?

 

[baddos]

If you enter the network command on a cisco IOS router w/ a subnet mask as 255.255.255.0 it will change it to the reverse format 0.0.0.255.

I always thought it was a dumb way to begin with and I'm glad the PIX does it the way it does.

 

[RoundAbout]

It's definitely screwy!

RoundAbout