Wednesday, January 6, 2016

ISIS task #1. Basic single area topology.

Topology:



This task includes routers R1, R2  (IOS )and R3 (IOS-XR). 
Initial configuration include loopback0 interface on each router, and links between the routers.

Requirements:

1. Configure ISIS as routing protocol to provide connectivity between the routers. 
2. Use area number 49.0001.
3. System-ID should be 0000.0000.000X, where X is the router number. 
4. All devices should use only ISIS Level-2 routing. 
5. R3 should be the DIS on the segment R1-R3. 
6. R2 should be the DIS on the segment R2-R3.
7. There should be no CSNP flooding on segment R1-R2. 

Solution:

Highlight the text below to reveal the solution.

This is basic ISIS single level configuration. 
Segments R1-R3 and R2-R3 should be configured as multiaccess segments, on which DIS is elected.
Configure the priority to affect the DIS election process. 
Segment R1-R2 should be configured point-to-point. CSPN are only flooded by DIS on multiaccess segment. 

R1:


!
interface Ethernet0/0
 ip address 11.0.13.1 255.255.255.0
 ip router isis CCIE
 isis circuit-type level-2-only
!
interface Ethernet0/1
 ip address 11.0.12.1 255.255.255.0
 ip router isis CCIE
 isis circuit-type level-2-only
 isis network point-to-point
!
interface Loopback0
 ip address 11.0.1.1 255.255.255.255
 ip router isis CCIE
 isis circuit-type level-2-only
!
router isis CCIE
 net 49.0001.0000.0000.0001.00
!

R2:

!
interface Ethernet0/0
 ip address 11.0.23.2 255.255.255.0
 ip router isis CCIE
 isis circuit-type level-2-only
 isis priority 127
!
interface Ethernet0/1
 ip address 11.0.12.2 255.255.255.0
 ip router isis CCIE
 isis circuit-type level-2-only
 isis network point-to-point
!
interface Loopback0
 ip address 11.0.2.2 255.255.255.255
 ip router isis CCIE
 isis circuit-type level-2-only
!
router isis CCIE
 net 49.0001.0000.0000.0002.00
!

R3:

!
router isis CCIE
 net 49.0001.0000.0000.0003.00
 interface Loopback0
  address-family ipv4 unicast
  !
 !
 interface GigabitEthernet0/0/0/0
  circuit-type level-2-only
  priority 127
  address-family ipv4 unicast
  !
 !
 interface GigabitEthernet0/0/0/1
  circuit-type level-2-only
  address-family ipv4 unicast
  !
 !
!

Verification:

R1#show isis neighbors

Tag CCIE:
System Id      Type Interface   IP Address      State Holdtime Circuit Id
R2             L2   Et0/1       11.0.12.2       UP    22       00
R3             L2   Et0/0       11.0.13.3       UP    8        R3.03

R1#sh ip route isis
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP
       + - replicated route, % - next hop override

Gateway of last resort is not set

      11.0.0.0/8 is variably subnetted, 8 subnets, 2 masks
i L2     11.0.2.2/32 [115/20] via 11.0.12.2, 00:11:11, Ethernet0/1
i L2     11.0.3.3/32 [115/20] via 11.0.13.3, 00:09:27, Ethernet0/0
i L2     11.0.23.0/24 [115/20] via 11.0.13.3, 00:09:27, Ethernet0/0
                      [115/20] via 11.0.12.2, 00:09:27, Ethernet0/1


R2# show isis neighbors

Tag CCIE:
System Id      Type Interface   IP Address      State Holdtime Circuit Id
R1             L2   Et0/1       11.0.12.1       UP    27       00
R3             L2   Et0/0       11.0.23.3       UP    26       R2.01

RP/0/0/CPU0:R3#show isis neighbors
Sun Dec 13 18:41:31.243 UTC

IS-IS CCIE neighbors:
System Id      Interface        SNPA           State Holdtime Type IETF-NSF
R1             Gi0/0/0/0        aabb.cc00.0400 Up    23       L2   Capable
R2             Gi0/0/0/1        aabb.cc00.0100 Up    7        L2   Capable



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