From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Sun Sep 07 2003 - 15:05:19 GMT-3
First off let me start by saying that there are two types of IS-IS
hellos (IIH's), point-to-point and LAN. The IIH types used by IS-IS on
an interface is based on the type of interface (point-to-point or
multipoint)*. This is similar in a way to how OSPF determines the
network type of an interface based off the type of interface being used.
But unlike OSPF, IS-IS does not have any commands to change the default
IIH type until IOS version 12.2(8)T.
As of 12.2(8)T Cisco introduced a new IS-IS command that will allow the
changing of the IIH type used for an interface from LAN IIH to
point-to-point IIH but not from point-to-point to LAN. This new command,
isis network point-to-point, can be applied to a multipoint interface
(multipoint subinterface, physical Frame-Relay interface, Ethernet
interface, etc).
Basically one of the issues that you are seeing is that the
point-to-point interface is sending point-to-point IIH's and physical
interface is sending LAN IIH's. The IIH types need too of course match
on each end for IS-IS to work properly. The second issue is that you
need to map CLNS on the physical interface and include the broadcast
keyword.
Here is what will work by default:
1. point-to-point subinterface to a point-to-point subinterface
2. physical interface to a physical interface
3. multipoint subinterface to a multipoint subinterface
4. multipoint subinterface to a physical interface
Here is what does not work by default:
1. point-to-point subinterface to a physical interface
2. point-to-point subinterface to a multipoint subinterface
Here is what will work using the new IS-IS command on the 'multipoint'
interface side:
1. point-to-point subinterface to a physical interface
1. point-to-point subinterface to a multipoint subinterface
Remember that if you are going to run ISIS over Frame-Relay on a
multipoint subinterface or a physical interface, you will need to map
CLNS to the DLCI and include the broadcast keyword. This also applies to
a physical BRI, physical ATM or an ATM multipoint subinterface.
*Note: There are generally speaking two types of interfaces,
point-to-point and multipoint. HDLC serial interfaces, dialer interfaces
or Frame-Relay point-to-point subinterfaces are examples of
point-to-point interface types. Ethernet interfaces, physical
Frame-Relay interfaces, multipoint subinterfaces, BRI interfaces are
generally considered multipoint in that they can have more than one
device connected to them.
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Toll Free: 877-334-8987
Direct: 775-745-6404 (Outside the US and Canada)
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
SN K38U
Sent: Saturday, September 06, 2003 11:28 PM
To: ccielab@groupstudy.com
Subject: isis neighbor adj problem
Hi group#,when I worked on a lab recently,I encountered a problem about
isis neighbor adj.
Here is my topology:
r3-s1--(frame-relay)--s0-r4-| e0
|
s0
below is the detailed config:
r3:
interface Serial0
no ip address
encapsulation frame-relay
frame-relay lmi-type ansi
!
interface Serial0.1 point-to-point
ip address 10.13.1.2 255.255.0.0
ip router isis
frame-relay interface-dlci 301
!
interface Serial1
ip address 10.34.1.1 255.255.0.0
ip router isis
encapsulation frame-relay
frame-relay interface-dlci 304
frame-relay lmi-type ansi
!
router isis
net 01.3333.3333.3333.00
r4:
interface Ethernet0
ip address 10.4.1.1 255.255.0.0
ip router isis
!
interface Serial0
ip address 10.34.1.2 255.255.0.0
ip router isis
encapsulation frame-relay
frame-relay interface-dlci 403
frame-relay lmi-type ansi
!
router isis
net 01.4444.4444.4444.00
I found that r3 and r4 cannot form isis neighbors.
When i debug the isis neighbor adj,here is the output:
r3#debug isis adj
IS-IS Adjacency related packets debugging is on
r3#
00:03:14: ISIS-Adj: Encapsulation failed for L1 LAN IIH on Serial1
00:03:15: ISIS-Adj: Encapsulation failed for L2 LAN IIH on Serial1
on r4,there is the same problem.
That confused me.The s0 should send serial IIH instead of LAN IIH since
it
is not a lan interface.Why the interface s0 does not behave normally?
What
cause this situation?
Who can help out the problem? I wasted too much time on it.
Please clarify it. Thanks a lot for any help!
This archive was generated by hypermail 2.1.4 : Wed Oct 01 2003 - 07:24:24 GMT-3