From: Gustavo Novais (gustavo.novais@novabase.pt)
Date: Sun Aug 14 2005 - 10:11:07 GMT-3
Hello
Chris, once again, you hit the spot! :)
I was looking at the route table and the show isis db detail, and I
didn't notice that the IP address of the router who originated the LSP,
was different from the IP address of the next hop on the route.
Basically it is very similar to OSPF's behaviour.
Thank you for your help.
Gustavo
-----Original Message-----
From: Chris Lewis (chrlewis) [mailto:chrlewis@cisco.com]
Sent: domingo, 14 de Agosto de 2005 9:01
To: Gustavo Novais; ccielab@groupstudy.com
Subject: RE: distance command 2nd take - Correction to previous post
Gustavo,
Apologies for previous post, it was incorrect. That's the trouble with
travelling to other continents and replying from hotel rooms when one
cannot sleep :)
Using the config previously posted, if I add a second loopback to R1
(50.50.50.0) and advertize it via ISIS, that route also has an AD of
120, even though I do not change the access list on R3, as looking at
the routing table on R3 shows:
50.0.0.0/24 is subnetted, 1 subnets
i L1 50.50.50.0 [120/20] via 172.16.31.1, Serial1/0
172.16.0.0/16 is variably subnetted, 4 subnets, 3 masks
C 172.16.136.0/26 is directly connected, Ethernet0/0
C 172.16.32.0/24 is directly connected, Serial3/0
C 172.16.35.0/30 is directly connected, Serial4/0
C 172.16.31.0/30 is directly connected, Serial1/0
11.0.0.0/24 is subnetted, 1 subnets
i L1 11.11.11.0 [120/20] via 172.16.31.1, Serial1/0
122.0.0.0/24 is subnetted, 1 subnets
Now if there is another router peering with R3 that is advertizing
122.122.122.0, we get the following:
122.0.0.0/24 is subnetted, 1 subnets
i L1 122.122.122.0 [115/20] via 172.16.35.2, Serial4/0
So routes with the following config on R3
router isis
net 49.0001.3333.3333.3333.00
distance 120 11.11.11.0 0.0.0.255
Give the following: from R1 have AD 120, other CLNS neighbors have AD
115
So looking at the loopback addresses on R1, we get
Interface IP-Address OK? Method Status
Protocol
Loopback0 192.168.1.1 YES NVRAM up
up
Loopback10 11.11.11.11 YES manual up
up
Loopback50 50.50.50.50 YES manual up
up
So the help is correct, it is a source address, if you need to know what
source address to use, issue the following command and you see that to
filter routes from R1, you need to identify 11.11.11.11 as the source
address.
R3#sho isis data det
IS-IS Level-1 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime
ATT/P/OL
Router1.00-00 0x00000008 0x0B96 1064 0/0/0
Area Address: 49.0001
NLPID: 0xCC
Hostname: Router1
IP Address: 11.11.11.11
Metric: 10 IP 172.16.31.0 255.255.255.252
Metric: 10 IP 11.11.11.0 255.255.255.0
Metric: 10 IP 7.7.7.0 255.255.255.0
Metric: 10 IP 50.50.50.0 255.255.255.0
Metric: 10 IS R3.00
R3.00-00 * 0x00000004 0x614C 458 0/0/0
Area Address: 49.0001
NLPID: 0xCC
Hostname: R3
IP Address: 172.16.35.1
Metric: 10 IP 172.16.31.0 255.255.255.252
Metric: 10 IP 172.16.35.0 255.255.255.252
Metric: 10 IS Router1.00
Metric: 10 IS Router5.00
Router5.00-00 0x00000004 0x8250 428 0/0/0
Area Address: 49.0001
NLPID: 0xCC
Hostname: Router5
IP Address: 122.122.122.122
Metric: 10 IP 172.16.35.0 255.255.255.252
Metric: 10 IP 122.122.122.0 255.255.255.0
Metric: 10 IS R3.00
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gustavo Novais
Sent: Saturday, August 13, 2005 5:19 PM
To: ccielab@groupstudy.com
Subject: distance command 2nd take
Hello
This issue was debated on a previous discussion, but not regarding ISIS.
When you wish to increase distance of routes from one source speaking
ISIS, (let's say 1.1.1.1) you'd insert the command distance 120 1.1.1.1
0.0.0.0 It does not work. When I do distance 120 0.0.0.0 255.255.255.255
in deed I'm able to increase distance, but I'd like something more
granular.
I think that I'm failing to identify the source from which the routing
update is coming from, but I have 1.1.1.1 in my table as next hop of the
route.
In OSPF you have to identify the neighbor ID for this command fo work as
expected
Is it because the route is carried on a LSP and the source is not
identifiable as an IP address, as is OSPF?
I'd appreciate your thoughts...
Thanks
Gustavo
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