From: Usankin, Andrew (Andrew.Usankin@twtelecom.com)
Date: Thu Aug 23 2007 - 13:46:11 ART
Type 5 LSA has forwarding address of router which does redistribution of
external route. If this forwarding address is not reachable router is
removed from routing table.
Routing TCP/IP Vol 1., Chapter 8, example 8-63
"The forwarding address is the loopback interface of Wyeth. If the
forwarding address in an external LSA is specified, and this address is
not reachable, the address contained in the LSA is not inserted into the
route table. When Pena translates type 7 NSSA LSAs into type 5 LSAs, by
default the forwarding address is transferred from the type 7 to the
type 5. The ABR can be configured to suppress the forwarding address
during the translation, replacing the specified address with the address
0.0.0.0. When another router receives the type 5 external LSA with the
forwarding address suppressed, instead of trying to direct traffic for
the external address to the forwarding address, the receiving router
will attempt to direct the traffic to the type 7 to type 5 translating
ABR router."
Andrew
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
sirus MOGHADASIAN
Sent: Thursday, August 23, 2007 4:22 AM
To: Cisco certification
Subject: OSPF Adv Tech Labs, problem:strange area range command issue
I have a simple scenario. (it's diagram is as same as advance
technologies lab of IE ,OSPF,NSSA area ABR External prefix Filtering)
|-----R4
R6 -----| ----frame-Relay ---R5
|-----R1
R6 connects to R4 and R1 through ethernet segment (area 1)
,and R4 ,R1 ,R5 are connected by frame-relay cloud (R5 hub and R4 ,R1
spoke) (area 0)
R6 configuration:
int loopback ip 6.6.6.6/32 .
ip route 120.0.0.1 255.255.255.255 null0
router ospf 1
redistribute static
area 1 nssa
when I configure "area 1 range 6.6.6.6 255.255.255.255 not-advertised"
on
R4 something very strange happens.
6.6.6.6 removed from R5 as expected, but I 120.0.0.1 removed as well
!!!
and no longer I cannot see 120.0.0.1 as my external route.
I configured area 1 as nssa (R1 R4 R6).
why my external route disappears????
by the way if i do not configure area 1 as nssa every thing works fine
thanks
This archive was generated by hypermail 2.1.4 : Sat Sep 01 2007 - 11:32:12 ART