Why Hello and Dead timers in OSPF should match and it should not match in EIGRP?

[raviccie12]

I was wondering why there is so much stress given on Hello and Dead intervals in OSPF. i.e. In ospf neighborship would not form if the hello and dead timers do not match?
Is there any specific reason behind this?

[Flavio Miranda]

Hi @raviccie12

 This is what makes a protocol reliable and is defined on the "genesis" of the protocol development as you can see on the Request For Comment.

The RFC for OSPF states that:

" All routers connected to a common network must agree on certain
parameters (Network mask, HelloInterval and RouterDeadInterval).
These parameters are included in Hello packets, so that differences
can inhibit the forming of neighbor relationships. A detailed
explanation of the receive processing for Hello packets is presented
in Section 10.5."

The protocol rely on this process to make sure that everything will work smoothly. 

-If I helped you somehow, please, rate it as useful.-

[raviccie12]

Thank you for responding @Flavio Miranda. EGRP is more reliable protocol as compared to OSPF when you consider the AD value, then also EIGRP does not has this requirement. Why is it so?

[Flavio Miranda]

I honestly don't like to compare protocol as each one has its own particularities and application.

 I don't agree, however, that EIGRP is more reliable. I've been working with network on the last 15 years and I saw EIGRP deployment once or twice. OSPF, in the other hand,  is the most used IGP on the market for decades.

 But, the reason why EIGRP behaves like this and not like that is inherent  to its creation. Cisco have found a different way to reach the reliability they believe is enough for this protocol. As EIGRP is a proprietary protocol, most of the underlying information is not public like an open protocol like OSPF.

-If I helped you somehow, please, rate it as useful.-

[Joseph W. Doherty]

"... EGRP is more reliable protocol as compared to OSPF when you consider the AD value ..."

Hmm, who determined the AD default values on a Cisco router?

Hmm, who developed EIGRP?

;)