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| Title: | DEC Network Integration Server (DECNIS) |
| Notice: | Please read note 1 to use this conference effectively |
| Moderator: | MARVIN::WELCH |
|
| Created: | Wed Sep 18 1991 |
| Last Modified: | Thu Jun 05 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 3660 |
| Total number of notes: | 15082 |
3599.0. "RIP to IS-IS propagation, special situation question" by SCASS1::ROCHELEAU (Rod Rocheleau - 972-527-2272) Thu Apr 10 1997 16:34
We have a situation in converting a group of DECNIS's from Phase IV to IS-IS
routing where the behavior of the routing tables is not totally understood.
Situation:
12 DECNIS routers connected to a FDDI ring that acts as a concentration point,
referred to as a WANlan. Each of the 12 routers also connects to other LAN's
and or remote routers via WAN links.
Also connected to the FDDI ring is a Gateway that connects to the Internet.
Problem:
In the current configuration, all routers on the WANlan trusts each other and
exchanges RIP routes, i.e. the Gateway to the Internet is know via RIP and is
directly reachable by each router.
When the routers are converted to IS-IS, we had intended to pick two of the
twelve routers and use them to trust the Gateway (i.e. learn the RIP routes
from the Gateway) and then propagate the learned subnets into IS-IS. One of
the routers would propagate at a metric value of 0, the other would have
he metric incremented by two.
The problem (we think) is that the other routers will allways go to the
router that introduces the RIP route into IS-IS. Is this correct or will
the routers learn via ICMP redirects the correct route to the Internet Gateway
and not have to make an extra hop?
If the extra hop occurs, can we setup all routers on the WANlan to accept the
RIP routes from the gateway but only two propagate the RIP routes into IS-IS?
In other words will the RIP route learned from the Gateway override the route
that is in IS-IS?
Thanks
Rod
| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 3599.1 | routers don't listen to ICMP redirects | SHAND::shand | Mike Shand | Thu Apr 10 1997 20:16 | 7 |
| Hosts would be redirected by ICMP redirects, but routers will not be.
You should be able to set up all the routers to receive the RIP routes,
but have only two of them proagate into ISIS by suitable use of
propagation controls.
Mike
|
| 3599.2 | | MARVIN::PATEL | | Fri Apr 11 1997 05:18 | 6 |
| You are also going to need to propagate the IS-IS routes into RIP so the gateway
has routes back into your internal network or are you planning to achieve this
some other way.
As Mike says you are not going to be able to eliminate the extra hop since routers
ignore ICMP redirects. The only way to avoid this is to turn RIP on on all the
routers and then propagate the routes to/from I-ISIS.
|