From: Jung-I Lin (easyman.lin@gmail.com)
Date: Fri Oct 13 2006 - 07:35:25 ART
Hi, Arua
Thanks for joining the discussion.
But I don't agree on the following 2 points which you mentioned.
1. "Actually you will have to set the interface mode to only sparse-mode"
If you set the interface mode to sparse-mode, how would you falling back to
dense-mode if the rp fails/not exist for specific group?
I mean you have to set the interface in "sparse-dense-mode" to get the
chance to falling back to dense-mode operation, if the rp fails/not exist
for specific group.
This is the situation where the "no ip pim dm-fallback" would take effect.
2. "Dense mode flooding of AUTO-RP groups would still happen even when
sparse mode is
configured on interface."
Sparse-mode will not allow the auto-rp groups to be flood through, the only
exception is if you configure the "ip pim autorp listener" or "manually
configure a static rp on every transit routers".
Maybe I misunderstand something here.
Comments are appreciated.
On 10/13/06, Arun Arumuganainar <aarumuga@hotmail.com> wrote:
>
> Actually "no ip dm-fallback" will set RP for groups that do no have known
> RP
> to 0.0.0.0
>
> The basis idea here is to prevent dense-mode operation for non-auto RP
> groups .Actually you will have to set the interface mode to only
> sparse-mode
>
>
> Note : SPARSE-DENSE-MODE do not have any meaning here since Dense mode
> operation will never happen if you enable this command . Only exception to
> this rule is Auto-RP groups , It is interesting to note that Dense mode
> flooding of AUTO-RP groups would still happen even when sparse mode is
> configured on interface.
>
> Alternate Strategy on IOS image that do not support this command.
>
> On IOS images that do not support this command pls. follow the following
> strategy.
>
> 1) Configure all PIM interface with sparse-dense-mode
> 2) Configure any of the loopback interface as static rp(
> WITHOUT
> OVERRIDE command ) for all groups except auto-rp groups
>
> When you do this router will behave the same way as when you turned on "
> no
> ip dm-fallback" command .
>
> Hope this helps.
>
> Thanks and Regards
> Arun
>
> ----- Original Message -----
> From: "Jung-I Lin" <easyman.lin@gmail.com>
> To: "STEELFIN" <steelfin@gmail.com>
> Cc: <ccielab@groupstudy.com>
> Sent: Friday, October 13, 2006 6:01 AM
> Subject: Re: no ip pim dm-fallback
>
>
> > Hi, STEELFIN
> > This command is introduced in ver 12.3(4)T.
> > You might not see this command in your IOS version 12.3(20).
> >
> > As you can see this command is use to prevent "falling backup to
> > dense-mode".
> > What would cause a router falling back to dense-mode?
> > If the interface are in sparse-only-mode, it rely on RP(staticly or
> > dynamically) to join/transmit to the group.
> > If no RP exist for that group, then it is unable to join/transmit to the
> > group.
> >
> > But if the interface is in sparse-dense-mode, it will switch the group
> to
> > dense-mode operation if the rp fails or not exist for that group.
> >
> > The dm-fallback command is used in this situation, if you do not want
> the
> > router switch to dense-mode while the interface is configured in
> > "sparse-dense-mode".
> > You can issue "no ip pim dm-fallback". (This command is on by default)
> >
> > Note this command will not affect the two "auto-rp" group
> > 224.0.1.39/224.0.1.40.
> > These two group will always in dense-mode(if you configured
> sparse-dense-mod
> > on interfaces).
> >
> > HTH.
> >
> > On 10/13/06, STEELFIN <steelfin@gmail.com> wrote:
> > >
> > > Hi
> > >
> > > Is the "no ip pim dm-fallback" command used with sparse mode ? All of
> the
> > > documentation I read state that it is a command and should be entered
> on
> > > all
> > > sparse-mode routers to prevent fallback to dense mode in the event of
> RP
> > > failure.
> > >
> > > I am unable to enter this command :
> > >
> > > ROM: System Bootstrap, Version 12.2(7r) [cmong 7r], RELEASE SOFTWARE
> (fc1)
> > > ROM: C2600 Software (C2600-ADVENTERPRISEK9-M), Version 12.3(20),
> RELEASE
> > > SOFTWARE (fc2)
> > >
> > > R2(config)#no ip pim ?
> > > accept-register Registers accept filter
> > > accept-rp RP accept filter
> > > autorp Configure AutoRP global operations
> > > bidir-enable Enable Bidir-PIM
> > > bsr-candidate Candidate bootstrap router (candidate BSR)
> > > log-neighbor-changes Log PIM neighbor up/down and DR changes
> > > register-rate-limit Rate limit for PIM data registers
> > > register-source Source address for PIM Register
> > > rp-address PIM RP-address (Rendezvous Point)
> > > rp-announce-filter Auto-RP announce message filter
> > > rp-candidate To be a PIMv2 RP candidate
> > > send-rp-announce Auto-RP send RP announcement
> > > send-rp-discovery Auto-RP send RP discovery message (as
> RP-mapping
> > > agent)
> > > spt-threshold Source-tree switching threshold
> > > ssm Configure Source Specific Multicast
> > > state-refresh PIM DM State-Refresh configuration
> > > vrf Select VPN Routing/Forwarding instance
> > >
> > > Is this command no longer available?
> > >
> > > Thank you
> > >
> > > SF
> > >
> > >
> _______________________________________________________________________
> > > Subscription information may be found at:
> > > http://www.groupstudy.com/list/CCIELab.html
> > >
> >
> >
> >
> > --
> > Thanks
> > Best Regards,
> >
> > Jung-I Lin
> >
> > _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
> >
>
>
-- Thanks Best Regards,Jung-I Lin
This archive was generated by hypermail 2.1.4 : Wed Nov 01 2006 - 07:29:05 ART