@CurtisJTroabugh wrote:

So, first I should mention I am brand new to IS-IS, so I may be misunderstanding exactly what the configuration should be. The issue: L1/L2 routers that have connections to different areas are not setting the ATT bit when sending LSPs to L1 routers inside local areas. Below is a simple topology that demonstrates the issue.

As I understand, the L2/L1 router should do two things; one, advertise the L1 routes it knows from its area (such as the loopback on R3; 192.168.0.3) to the other area; and two, set the ATT bit in the LSPs being sent to the L1-Only router, R3. R3 should then generate a default route pointing to the source of the LSP that had the ATT bit set; in this case R2 I have confirmed that R1 sees the loopback on R3.

R1>show ip route isis | b Gateway
Gateway of last resort is not set

  10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
i L2     10.0.0.8/30 [115/2] via 10.0.0.6, 00:21:04, GigabitEthernet0/1
  192.168.0.0/32 is subnetted, 3 subnets`
i L2     192.168.0.2 [115/11] via 10.0.0.6, 00:21:04, GigabitEthernet0/1
i L2     192.168.0.3 [115/12] via 10.0.0.6, 00:19:04, GigabitEthernet0/1

Looking on R3, I first noticed that no default route had been generated.

R3>show ip route isis | b Gateway
Gateway of last resort is not set

  10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
i L1     10.0.0.4/30 [115/2] via 10.0.0.9, 00:24:56, GigabitEthernet0/1
  192.168.0.0/32 is subnetted, 2 subnets
i L1     192.168.0.2 [115/11] via 10.0.0.9, 00:24:56, GigabitEthernet0/1

Also, looking at the LSPs there are no ATT bits set for any LSP.

R2>show isis database 

Tag 1:
IS-IS Level-1 Link State Database:
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime      ATT/P/OL
R2.00-00            * 0x00000006   0xC78A        540               0/0/0
R3.00-00              0x00000006   0x1374        672               0/0/0
IS-IS Level-2 Link State Database:
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime      ATT/P/OL
R1.00-00              0x00000004   0x5D58        567               0/0/0
R2.00-00            * 0x00000009   0x32A0        595               0/0/0

R3>show isis database 

Tag 1:
IS-IS Level-1 Link State Database:
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime      ATT/P/OL
R2.00-00              0x00000006   0xC78A        642               0/0/0
R3.00-00            * 0x00000006   0x1374        779               0/0/0`

Below is my IS-IS configuration for each router.

R1

R1#show running-config | s interface|router
interface Loopback0
 description Loopback
 ip address 192.168.0.1 255.255.255.255
 ip router isis 1
interface GigabitEthernet0/0
 description OOB Management
 vrf forwarding Mgmt-intf
 ip address 10.255.0.108 255.255.0.0
 duplex full
 speed auto
 media-type rj45
interface GigabitEthernet0/1
 description to R2
 ip address 10.0.0.5 255.255.255.252
 ip router isis 1
 duplex full
 speed auto
 media-type rj45
 isis circuit-type level-2-only
 isis network point-to-point 
 isis metric 1
router isis 1
 net 49.0001.0000.0001.00
 metric-style wide

R2

R2#show running-config | s interface|router
interface Loopback0
 description Loopback
 ip address 192.168.0.2 255.255.255.255
 ip router isis 1
interface GigabitEthernet0/0
 description OOB Management
 vrf forwarding Mgmt-intf
 ip address 10.255.0.106 255.255.0.0
 duplex full
 speed auto
 media-type rj45
interface GigabitEthernet0/1
 description to R1
 ip address 10.0.0.6 255.255.255.252
 ip router isis 1
 duplex full
 speed auto
 media-type rj45
 isis network point-to-point 
 isis metric 1
interface GigabitEthernet0/2
 description to R3
 ip address 10.0.0.9 255.255.255.252
 ip router isis 1
 duplex full
 speed auto
 media-type rj45
 isis network point-to-point 
 isis metric 1
router isis 1
 net 49.0023.0000.0002.00
 metric-style wide

R3

R3#show running-config | s interface|router
interface Loopback0
 description Loopback
 ip address 192.168.0.3 255.255.255.255
 ip router isis 1
interface GigabitEthernet0/0
 description OOB Management
 vrf forwarding Mgmt-intf
 ip address 10.255.0.107 255.255.0.0
 duplex full
 speed auto
 media-type rj45
interface GigabitEthernet0/1
 description to R2
 ip address 10.0.0.10 255.255.255.252
 ip router isis 1
 duplex full
 speed auto
 media-type rj45
 isis network point-to-point 
 isis metric 1
router isis 1
 net 49.0023.0000.0003.00
 is-type level-1
 metric-style wide

Please let me know if I am just making a dumb mistake or if there is a bug in them implementation of IS-IS in VIRL.

EDIT

So, it appears I need to do some more reading on what the NET actually is. After re-reading the text I am using I noticed that I have been using what's known as Minimal NET Format and not OSI NSAP Format. Once I changed the format of the NET address I was able to extend the Area Address out. Jezz bang head on table

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