From: Paresh Khatri (Paresh.Khatri@aapt.com.au)
Date: Fri Jul 15 2005 - 01:09:14 GMT-3
Hi Dillon,
Apart from using the new tags, I don't believe there is anywhere of distinguishing between internal and external routes when using wide-metrics.
Paresh.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of Dillon Yang
Sent: Friday, 15 July 2005 12:52 PM
To: Paresh Khatri; Group Study
Subject: Re: Doyle's comment vs ISIS external route
Hi, Paresh:
Thanks! It is may be the answer.
But I want a way to distinguish the external route for preventing loop, for the 12.2 dont support tag, you know. Then any advice on the distinction?
TIA
dillon
----- Original Message -----
From: "Paresh Khatri" <Paresh.Khatri@aapt.com.au>
To: "Dillon Yang" <dillony@gmail.com>; "Group Study" <ccielab@groupstudy.com>
Sent: Friday, July 15, 2005 10:11 AM
Subject: RE: Doyle's comment vs ISIS external route
Hi Dillon,
Doyle is both right (from a standards perspective) and wrong (from a Cisco perspective).
If you read RFC1195, you will see that external routes are only allowed to be originated by L2 routers. That is the standard. However, Cisco *does"* allow the use of TLV 130 (IP External Reachability Information TLV) in L1 LSPs. And it is from that that your confusion arises. Note that the above only applies when using narrow metrics.
When using wide metrics, the only TLV used is TLV 135 (The Extended IP Reachability TLV) - check out RFC3784. This TLV has no concept of internal or external, which explains the results you see.
HTH,
Paresh.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of Dillon Yang
Sent: Thursday, 14 July 2005 12:57 AM
To: Group Study
Subject: Doyle's comment vs ISIS external route
Hi, group:
I am finding a way to distinguish ISIS internal or external route, but I found something strange:
[Question01]
<quote from Doyle's book>
Whereas L2 routes may be either internal or external, L1 routes are always internal.
</quote>
You see, under L1-only routing, the router is generating the "IP-External" routes, and the routes was in the routing table.
How can you explain this problem, if you were Mr. Doyle?
[config01]
!
interface Loopback11
ip address 11.6.6.1 255.255.255.0
!
interface Loopback12
ip address 11.6.7.1 255.255.255.0
!
interface Loopback13
ip address 11.6.8.1 255.255.255.0
!
interface Loopback14
ip address 11.6.9.1 255.255.255.0
!
interface Loopback211
ip address 211.211.211.1 255.255.255.0
ip router isis fr
!
interface Ethernet0
ip address 150.100.2.254 255.255.255.0
ip router isis fr
no ip route-cache
no ip mroute-cache
clns router isis fr
!
!
router isis fr
net 49.0001.9999.9999.9999.00
redistribute connected metric-type external level-1
is-type level-1
!
end
R6#s isis dat det
IS-IS Level-1 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
R4.00-00 0x00000015 0xFF15 626 1/0/0
Area Address: 49.0001
NLPID: 0x81 0xCC
Hostname: R4
IP Address: 150.100.2.3
Metric: 10 IP 150.100.2.0 255.255.255.0
Metric: 10 IS R6.02
Metric: 0 ES R4
R6.00-00 * 0x00000015 0xFA76 642 0/0/0
Area Address: 49.0001
NLPID: 0x81 0xCC
Hostname: R6
IP Address: 211.211.211.1
Metric: 10 IP 150.100.2.0 255.255.255.0
Metric: 10 IP 211.211.211.0 255.255.255.0
Metric: 10 IS R6.02
Metric: 0 ES R6
Metric: 64 IP-External 11.6.9.0 255.255.255.0
Metric: 64 IP-External 11.6.8.0 255.255.255.0
Metric: 64 IP-External 11.6.7.0 255.255.255.0
Metric: 64 IP-External 11.6.6.0 255.255.255.0
R6.02-00 * 0x00000012 0xC7B1 677 0/0/0
Metric: 0 IS R6.00
Metric: 0 IS R4.00
R6#
[Question02]
The more strange thing followed, when I added the command "metric-style wide", the router did not generate the "IP-External" routes and these routes did not appear in the routing table.
How can it works?
[config02]
R6#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R6(config)#router isis fr
R6(config-router)#metric
R6(config-router)#metric-style wi level-1
R6(config-router)#end
R6.00-00 * 0x00000007 0x951B 1187 1/0/0
Area Address: 01
NLPID: 0xCC
Hostname: R6
IP Address: 211.211.211.1
Metric: 10 IP 211.211.211.0/24
Metric: 10 IP 3.3.16.0/24
Metric: 10 IS-Extended R1.00
Metric: 0 IP 11.6.9.0/24
Metric: 0 IP 11.6.8.0/24
Metric: 0 IP 11.6.7.0/24
Metric: 0 IP 11.6.6.0/24
routing table:
<omitted>
C 211.211.211.0/24 is directly connected, Loopback211
3.0.0.0/24 is subnetted, 16 subnets
i L1 3.3.10.0 [115/74] via 3.3.16.1, Serial0.601, fr
i L1 3.3.13.0 [115/30] via 3.3.16.1, Serial0.601, fr
i L1 3.3.14.0 [115/30] via 3.3.16.1, Serial0.601, fr
<omitted>
TIA
dillon
This archive was generated by hypermail 2.1.4 : Sun Sep 04 2005 - 17:00:30 GMT-3