From: Dillon Yang (gzdillon@hotmail.com)
Date: Tue Mar 22 2005 - 12:44:55 GMT-3
Hi, Kim:
For global connectivity, have you pinged the local bri ip address?
I tried every time, but failed. I think the local on fr can be ping from the command :
frame-relay map ip <local_add> <neighbor_dlci> broadcast, right? But the ISDN local address cannot be pinged by the command " dialer map ip <local_add> broadcast <neighbor_number>.
Anybody can resolve it? Maybe it cause me can not get 100% at IGP connectivity.
TIA
dillon
----- Original Message -----
From: <Jongsoo.Kim@Intelsat.com>
To: <ccielab@groupstudy.com>
Sent: Tuesday, March 22, 2005 1:34 PM
Subject: My isdn summary
> This is just my summary note but I post here maybe some of you can share
> some thoughts.
>
> Any comment is welcomed.
>
> First, most ISDN task is asked for back-up link to create a full
> reachability to stub router in case of F/R link failure.
> This keyword is to restore full reachability. It is only possible by 1) two
> floating static routes ( default route from stub router to the rest of
> network and a specific static route from the other router to the stub
> router), 2) ip ospf demand circuit or Rip tigger w/ more metric , 3) Dynamic
> routing protocol w/ dialer watch group and supressing routing protocol over
> ISDN, 4)back-up link 5) Rip w/ Snapshot routing.
>
> 1)Two floating static route is very straight forward and interesting traffic
> could be all ip packet.
> All IP traffic can be interesting traffic
>
> 2-1) ip ospf demand circuit is also straight forward and "no peer
> neighbor.." is important to prevent link flapping.
> The dynamic link cost needs to be something high to play a similar role as
> floting route with higher AD.
> I don't think ip OSPF cost need any value . I think OSPF Demand link has a
> high cost by default.
> All IP traffic can be interesting traffic.
>
> 2-2) Rip trigger will require higher metric ( off-set). Otherwise, traffic
> may continue to flow over ISDN after F/R is restored.
> All IP traffic can be interesting traffic. To function as back-up link, Rip
> need to run over ISDN as trigger mode and F/R as any mode.
>
> 3) If Dialer watch group is configured to bring up ISDN link, an IGP
> protocol should run across ISDN link to reslove full reachability.
> It is because dialer watch group doesn't create any route itself in to route
> look-up table. But what is important is to make this IGP protocol hello or
> update not interesting traffic. This will make normall case, igp peering
> down, but when dialer watch group trigger, igp will be able to send hello so
> that igp will be able to update routing table, which will create full
> reachability. If IGP is OSPD, then ip ospf demand circuit will cover most
> case of back-up. But dialer watch group can be used to meet a specific task
> such as dial ISDN if Vlan X dispear from routing table even if frame-relay
> is up, or ISDN should be up until F/R is up or until VLAN X show up again on
> ISDN. Ip OSPF demand will can make ISDN up when there is topological change
> but as long as topology is stable even with F/R down and if there is no
> interesting traffic, the ISDN link will eventually go down. Also some
> other advantage of dialer watch is that it doesn't care of topologic change
> while IP ospf demand or rip tigger will dial isdn when there is topological
> changes that have nothing to do with F/R link.
>
> 4) Back-up link is much simpler than dialer watch. It doesn't have to
> supress IGP hello. It doesn't need high IGP link cost. For this reason,
> most task will ask not to use back-up link, which is the problem.
>
> 5) Snapshot routing is basically used to supress rip route update over ISDN.
> With higher rip metric over ISDN, it can function as back-up link if rip
> runs over f/r link and ISDN.
>
>
> Thanks
>
>
> Jongsoo
>
>
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>
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