IPv6: IS-IS or OSPFv3

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1

Hello,

I do have some confusion about which one is better for IPv6 in Service
Provider networks as far as IP routing and MPLS application is concern!

1. Which protocol should i use to support the IPv6 in network: ISIS or
OSPFv3?
    As ISIS has multi-topology feature that can give us capability to run
IPv4 network separate from IPv6 right! and same thing with OSPF: OSPFv2 will
be used for IPv4 routing and OSPFv3 will be used for IPv6 routing! again Its
look like resource utilization for both the protocol will be same as they
are going to use separate database for storing the routing or topology
information. ISIS still has advantage over OSPF as it does use the TLV
structure which can help in expanding network to support the new feature!

2. MPLS is not distributing label for IPv6 protocol so again there will not
be any IGP best path calcuated for any MPLS related application for IPv6!

3. what if i have already running OSPFv2 for IPv4 in the network then should
i think for migrating to ISIS?
   if yes then what are the advantages that I can look at for migrating my
network to IS-IS?

regards
Devang Patel

2

I do have some confusion about which one is better for IPv6 in Service
Provider networks as far as IP routing and MPLS application is concern!

General rule of thumb - use whichever you / your operation is most familiar
with.
  Using IS-IS today, use it for IPv6.
  Using OSPFv2 today, use OSPFv3 for IPv6.

If that isn't good enough for you, then you need to understand the
operational differences between the protocols, and which aspects are most
relevant to your environment. I can't answer that for you ...

1. Which protocol should i use to support the IPv6 in network: ISIS or
OSPFv3?
   As ISIS has multi-topology feature that can give us capability to run
IPv4 network separate from IPv6 right! and same thing with OSPF: OSPFv2

will

Yes, MT could be a benefit ... but "not the same thing" for OSPF.

be used for IPv4 routing and OSPFv3 will be used for IPv6 routing! again

Its

look like resource utilization for both the protocol will be same as

they

are going to use separate database for storing the routing or topology
information. ISIS still has advantage over OSPF as it does use the TLV
structure which can help in expanding network to support the new feature!

ISIS is generally considered easier to extend, but OSPF has proven to be
quite extensible itself ... a wash, for the most part.

2. MPLS is not distributing label for IPv6 protocol so again there will not
be any IGP best path calcuated for any MPLS related application for IPv6!

Yes, lack of a native IPv6 "control plane" could be something of (cough)
problem.

3. what if i have already running OSPFv2 for IPv4 in the network then

should

i think for migrating to ISIS?
  if yes then what are the advantages that I can look at for migrating my
network to IS-IS?

Again, IMHO this depends on way too many factors to make a simple, blanket
statement.

regards
Devang Patel

HTH!
/TJ

3

Both work and have advantages and disadvantages.

Personally, I like the fact that IPv4 and IPv6 control plane are different, thus I'd go for OSPv3. ISIS-MT means you have to know that all your ISIS speakers will handle the MT packets gracefully. I know products from large vendors in the market which do not (IPv6 not enabled, it receives IPv6 MT packets, affects IPv4 ISIS control plane badly).

4

Personally, I like the fact that IPv4 and IPv6 control plane are
different, thus I'd go for OSPv3.

I totally agree on the discrete/segregated control planes, although note
that - for those who want it - OSPFv3 will "soon" be able to do IPv4 route
exchange as well ...

/TJ

5

TJ wrote:

Personally, I like the fact that IPv4 and IPv6 control plane are
different, thus I'd go for OSPv3.

I totally agree on the discrete/segregated control planes, although note
that - for those who want it - OSPFv3 will "soon" be able to do IPv4 route
exchange as well ...

Only if the vendors pick up on those changes.

Kind regards,
Martin List-Petersen

6

Juniper support this since JunOS 9.2 (draft-ietf-ospf-af-
alt-06.txt).

Cheers,

Mark.

7

Personally, I like the fact that IPv4 and IPv6 control plane are
different, thus I'd go for OSPv3.

I totally agree on the discrete/segregated control planes, although note
that - for those who want it - OSPFv3 will "soon" be able to do IPv4

route

exchange as well ...

Only if the vendors pick up on those changes.

Well, of course - just like anything else.
That was part of the reason for the scary-quotes around soon ...

/TJ

8

TJ wrote:

I do have some confusion about which one is better for IPv6 in Service
Provider networks as far as IP routing and MPLS application is concern!
    
General rule of thumb - use whichever you / your operation is most familiar
with. Using IS-IS today, use it for IPv6.
  Using OSPFv2 today, use OSPFv3 for IPv6.
  

Well, OSPFv3 has enough differences from OSPFv2 to make switching to IS-IS a benefit to stop people making mistakes through expected operational similarity (if that makes sense).

Also it means that once you're doing v6 everywhere you can dump OSPFv2 and only have one IGP for both v4 and v6. I personally think that'll save a lot of headaches down the line, not to mention that fact that IS-IS is, IMHO, a much nicer IGP to work with.

adam.

9

... not to mention that fact that IS-IS is, IMHO, a much nicer IGP to work

with.

WRT that last sentence, that is an almost religious debate I was trying to
avoid starting ... :slight_smile:

/TJ

10

TJ wrote:

... not to mention that fact that IS-IS is, IMHO, a much nicer IGP to
work

with.

WRT that last sentence, that is an almost religious debate I was trying to
avoid starting ... :slight_smile:

I will offer a mantra that has helped me, over the years, about the indeed
religious wars that emerge when a New Technology or Youthful feature comes
to these two link state protocols. I begin to mutter "ISNT and OySPF".

11

TJ wrote:

... not to mention that fact that IS-IS is, IMHO, a much nicer IGP to work
    

with.

WRT that last sentence, that is an almost religious debate I was trying to
avoid starting ... :slight_smile:
  

Well IMHO it's a very important point to consider. This is a great chance to switch your IGP, if you've ever wanted to. You *need* to deploy a new one anyways, so it's a great opportunity to see if you can simplify your network by migrating. Especially as OSPFv3 *isnt* the same as OSPFv2, so you will have to learn new things either way!

Oh, and I *am* in the process of organising a Crusade to wipe out those heretical OSPF supporters once and for all... :wink:

adam.

12

... not to mention that fact that IS-IS is, IMHO, a much nicer IGP to

work with.

WRT that last sentence, that is an almost religious debate I was trying

to

avoid starting ... :slight_smile:

Well IMHO it's a very important point to consider. This is a great chance

to switch your IGP, if you've ever wanted to. You *need* to

And that is what I tell people too - if you are looking to change (in either
direction (or others!), mind you), this could be an excuse / opportunity.

deploy a new one anyways, so it's a great opportunity to see if you can
simplify your network by migrating. Especially as OSPFv3 *isnt* the same
as OSPFv2, so you will have to learn new things either way!

Well from a pragmatic/operational perspective OSPFv3 and OSPFv2 are "close
enough" that you would require _very_ little re-training.

Oh, and I *am* in the process of organising a Crusade to wipe out those
heretical OSPF supporters once and for all... :wink:

Funny, that is how most ISIS proponents seem to feel - but without the
smiley!

/TJ

13

There is no fundamental difference between ISIS and OSPF; it's all in
details and style. You might want to look at:

http://www.nada.kth.se/kurser/kth/2D1490/06/hemuppgifter/bhatia-manral-diff-isis-ospf-01.txt.html

Glen.