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New Member

OSPF vs IS-IS

Hi,

why there is variation in the usage of IGP (ospf/is-is) among ISPs. why some ISPs are using IS-IS while others use OSPF ?

what are the issues related to this ? whether management issues(cost, maintanance) or design issues(scalability, security)?

please tell me in detail.

thank you.

3 REPLIES
Cisco Employee

Re: OSPF vs IS-IS

Jaipal,

ISIS came out first followed by OSPF. Some ISPs were already running ISIS when OSPF came out and some others decided to go with the relative maturity of former when the latter came out.

There is advantages and disadvantages for both. I personally like ISIS as I feel you can scale it better without requiring to split your core in multiple levels (area in the OSPF terminology). For instance ISIS allows you to only advertise the Loopback interface IP address for each router (not yet available in OSPF). The other link prefixes can then be carried in BGP.

ISIS is also relatively easy to extend to support new protocols (Address Families) as only the addition of one or more TLVs (Type, Length, Value) is required.

OSPF on the other hand has more features and knobs to fine tune and adapt to a given network as it is widely used in the enterprise world.

Bottom line today is what protocol one feels most comfortable with.

Regards

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: OSPF vs IS-IS

Yes My Vote is too with IS-IS, cause i have some bad experiences with OSPF.

New Member

Re: OSPF vs IS-IS

hi,

can you please explain some of your bad experiences with OSPF. your will be really appreciated.

thank you.

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