TMS zl Management and Configuration Guide ST.1.1.100226

9-36
Routing
OSPF
With MD5 authentication, a router uses a secret key and the MD5 algorithm
to generate a message digest for a packet. Routers that receive the packet
dehash the message digest using the same key. If the dehashed message digest
matches the packet, the packet is authentic.
Authentication with MD5 is more secure than simple password authentica-
tion. Attackers can intercept a valid OSPF packet and read the simple pass-
word. However, message digests are unique to each packet and impossible to
generate without the secret key.
Simple password authentication is most useful for ensuring routers do not
send messages into networks in the wrong area. Simply configure a different
simple password for each network. MD5 authentication, on the other hand,
also protects against hackers.
Note You must set the same password or key for each interface on a network, but
you can set different passwords or keys for different networks. However, you
must use the same type of authentication (none, simple, or MD5) for every
network in an area.
You configure OSPF authentication in the Enable OSPF on an interface window.
See step 9 on page 9-45.
Configuring OSPF
The following sections explain how to configure OSPF settings on the HP
ProCurve TMS zl Module.
OSPF Configuration Considerations
Properly configuring areas is a large part of configuring OSPF. Before you
configure OSPF on your TMS zl Module, you should have a clear picture of
your network’s topology. You should know:
■ Each router’s role:
• Internal router
•ABR
•ASBR
■ Each router’s ID
■ The OSPF area for each directly connected network