Re: OSPF LSA type 3 filtering

IS-IS supports multiple routed protocols, i.e. IPv4 and IPv6, whereas
OSPF doesn't.

Also, in the time when MPLS-TE was emerging as a technology, IS-IS
behavior to flood unknown TLVs instead of resetting adjacencies when
it receives them (OSPF does that when it receives an unknown LSA).
meant a very controlled deployment of new technologies. The fact it's
not IP, also has some security benefits (cannot be remotely attacked).
Etc.

What Joseph said is... not quite the reason, since IS-IS also has a
requirement for a contiguous L2 area.

--
Marko Milivojevic - CCIE #18427 (SP R&S)
Senior CCIE Instructor - IPexpert
On Fri, Jan 4, 2013 at 10:34 AM, Imran Ali <immrccie_at_gmail.com> wrote:
> marko i need to know why they use  is-is over ospf
>
> On Fri, Jan 4, 2013 at 8:53 PM, Marko Milivojevic <markom_at_ipexpert.com>
> wrote:
>>
>> In reality, for this purpose, IS-IS and OSPF are pretty much the same
>> (Type 2 vs Pseudonode LSP). They both use a very similar approach to
>> solve the same calculation problem.
>>
>> Carriers tend to use IS-IS for one other reason (to some extent
>> remedied by OSPFv3). This is a separate discussion though.
>>
>> --
>> Marko Milivojevic - CCIE #18427 (SP R&S)
>> Senior CCIE Instructor - IPexpert
>>
>>
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