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Jay
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 Posted: Thu Aug 21, 2003 9:49 am Post subject: IS-IS DR |
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I am reading Doyle and am trying to make sure I understand the concept of
the DR in a IS-IS Network. Am I correct in assuming that the duty of the
is-is DR is to maintain the integrity of the areas link state database by
use of CSNP's? |
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The Real Slim Shady
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| Posted: Thu Aug 21, 2003 10:47 pm Post subject: Re: IS-IS DR |
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That's about it. There are some differences between the OSPF DR and ISIS
D-IS concepts. One of the most fundamental is that there is no backup D-IS
and whilst the D-IS maintains an adjacency with all IS's on the broadcast
segment, so do all other IS's. Every IS has an adjacency with every other.
Also, use the correct terminology - it's called a DR in OSPF. It's a
Designated IS (D-IS) in IS-IS. Remember this or you'll sound daft in
technical meetings - certainly in Europe at any rate.
Slim
"Jay" <jay@jay.com> wrote in message
news:ibY0b.5101$Nc.3242066@news1.news.adelphia.net...
| Quote: | I am reading Doyle and am trying to make sure I understand the concept of
the DR in a IS-IS Network. Am I correct in assuming that the duty of the
is-is DR is to maintain the integrity of the areas link state database by
use of CSNP's?
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Piotr Marecki
Guest
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| Posted: Thu Aug 21, 2003 11:24 pm Post subject: Re: IS-IS DR |
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"Jay" <jay@jay.com> wrote in message
news:ibY0b.5101$Nc.3242066@news1.news.adelphia.net...
| Quote: | I am reading Doyle and am trying to make sure I understand the concept of
the DR in a IS-IS Network. Am I correct in assuming that the duty of the
is-is DR is to maintain the integrity of the areas link state database by
use of CSNP's?
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Not only.
DIS also advertises pseudonode LSP which represents broadcast link
itself.Every IS on link reports in their LSP only connection to pseudo-node
, and pseudonode lsp contains zero cost link to each of IS . So actually
creation of pseudonode and it's representation of broadcast link from graph
topology point of view creates series on p-t-p links between all IS on
broadcast network and pseudonode.
It's worth noting that this approach complicates a little bit situation when
there are only two IS on broadcast link - for example on MAN vlan created
for two router p-t-p connection - draft "Point-to-point operation over LAN
in link-state routing protocols" helps to remove that overhead for sake of
efficiency.
pm |
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