IS-IS Lab 22 Multiple Topology Mode
Previous Next
Download Lab: VIRL | EVE-NG | GNS3
Image requirements:
Cisco IOSv (vios-adventerprisek9-m.vmdk.SPA.156-2.T)
Introduction:
By default IS-IS protocol use single topology for all enabled routed protocols. If IS-IS runs in the dual-stack configuration, there would be only one link-state database for both IPv4 and IPv6 routed protocols. The problem with this implementation could arise if, in the L1 area, not all routers enabled for both IPv4 and IPV6, for example, if in this topology node A1 and A2 do not support IPV6 they will have trouble to communicate with the rest of the routers over IPV4 protocol. To fix this problem network topology have to be reconfigured to support multiple IS-IS topologies one for IPv4 which will be the default topology and another for IPv6, enabled under IPv6 address-family for IS-IS in the global router configuration. This lab introduces IS-IS multiple topology mode, learn how to configure and verify this technology.
Nodes Access:
Enable: cisco
Username: cisco
Password: cisco
Topology:
Original L1 IS-IS topology for both IPv4 and IPv6:
IPv4 and IPv6 addressing scheme:
The diagram shows how routed protocols implemented for this lab, some IS-IS routers route both IPv4 and IPv6 and others only operate IPv4:
Scenario:
As outlined in the third diagram, in the IS-IS L1 area C000 some routers will be configured to run both IPv4 and IPv6 and some only IPv4. This topology has been configured for IS-IS to route IPv4 networks. The goal of this lab is to configure IS-IS for IPv6 partially and observe how this configuration will break IP connectivity in the topology. Later, to fix communication between routers, multiple topology mode will be implemented.
Lab tasks:
1. Verify connectivity between routers in the topology.
2. Partially enable IS-IS to route IPv6.
3. Configure Multiple Topology Mode.
4. Verify the implementation of multi-topology mode.
Lab procedure:
Step1: Access CLI of router A2 and ping multiple IP addresses. Verify connectivity to B2, D2, and E2:
A2#ping 192.168.0.6 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.6, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.10
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/6 ms
A2#ping 192.168.0.9 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.9, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.10
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 3/3/5 ms
A2#ping 192.168.0.7 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.7, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.10
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/6/7 ms
A2#
Successful ping indicates that there are no connectivity issues in the topology.
Step2: Access CLI of router C1 and verify its IS-IS configuration:
C1#show isis protocol
IS-IS Router: <Null Tag>
System Id: 0000.0000.00C1.00 IS-Type: level-1
Manual area address(es):
49.c000
Routing for area address(es):
49.c000
Interfaces supported by IS-IS:
GigabitEthernet0/3 - IP
GigabitEthernet0/2 - IP
GigabitEthernet0/1 - IP
Loopback0 - IP
Redistribute:
static (on by default)
Distance for L2 CLNS routes: 110
RRR level: none
Generate narrow metrics: none
Accept narrow metrics: none
Generate wide metrics: level-1-2
Accept wide metrics: level-1-2
C1#
The output shows that IS-IS only enables for IPv4.
Step3: Configure IS-IS for IPv6 on router C1, enable it for the same interfaces as shown in the output above:
C1(config)#interface range g0/1-3, lo0
C1(config-if-range)#ipv6 router isis
C1(config-if-range)#end
C1#
Step4: Observe the problem caused by configuration in the step3:
*Jan 4 19:05:22.827: %SYS-5-CONFIG_I: Configured from console by console
*Jan 4 19:05:28.893: %CLNS-5-ADJCHANGE: ISIS: Adjacency to C2 (GigabitEthernet0/1) Down, hold time expired
*Jan 4 19:05:29.958: %CLNS-5-ADJCHANGE: ISIS: Adjacency to D1 (GigabitEthernet0/3) Down, hold time expired
*Jan 4 19:05:46.788: %CLNS-5-ADJCHANGE: ISIS: Adjacency to A1 (GigabitEthernet0/2) Down, hold time expired
C1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C1#
To bring adjacencies back up, neighbors of C1 have to be configured the same way as C1, run IS-IS for both IPv4 and IPv6.
Step5: Configure IS-IS for IPv6 on router C2:
C2(config)#interface range g0/1-3, lo0
C2(config-if-range)#ipv6 router isis
Step6: Verify that C2 has IS-IS neighborship with router C1:
C2#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C1 L1 Gi0/1 10.0.0.33 UP 24 C2.01
Step7: Configure IS-IS for IPv6 on routers A1 and A2:
A1(config)#interface range g0/1-2, lo0
A1(config-if-range)#ipv6 router isis
!
A2(config)#interface range g0/1, lo0
A2(config-if-range)#ipv6 router isis
Step8: Configure IS-IS for IPv6 on routers B1 and B2:
B1(config)#interface range g0/1-2, lo0
B1(config-if-range)#ipv6 router isis
!
B2(config)#interface range g0/1, lo0
B2(config-if-range)#ipv6 router isis
Step9: Verify IPv4 and IPv6 connectivity to router A2 from router B2:
B2#ping 192.168.0.10 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.10, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.6
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/6/9 ms
B2#ping 2001:DB8:B:0:1::3 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:B:0:1::3, timeout is 2 seconds:
Packet sent with a source address of 2001:DB8:B:0:1::5
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/5/6 ms
Both IPv4 and IPv6 connectivity confirmed.
Step10: Verify if router D2 able to ping router E2:
D2#ping 192.168.0.7
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.7, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Obviously, ping failed due to neighborship issue between routers C1 and D1, and routers C2 and E1, but D routers and E routers should not be enabled for IPv6 IS-IS, the fix for this problem is to configure multiple topology mode on the dual-stack enabled routers.
D1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C1 L1 Gi0/2 10.0.0.5 INIT 29 D1.02
D2 L1 Gi0/1 10.0.0.30 UP 8 D2.01
E1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C2 L1 Gi0/2 10.0.0.37 INIT 29 E1.02
E2 L1 Gi0/1 10.0.0.14 UP 24 E1.01
Both D1 and E1 shows that neighborship with C routers in the INIT state.
Step11: Before configuring multiple topology mode verify detail database on the dual-stack enabled nodes C1 and C2:
C1#show isis database detail C1.00-00
IS-IS Level-1 LSP C1.00-00
LSPID LSP Seq Num LSP Checksum LSP Holdtime/Rcvd ATT/P/OL
C1.00-00 * 0x0000000C 0xDE22 599/* 0/0/0
Area Address: 49.c000
NLPID: 0xCC 0x8E
Hostname: C1
Metric: 10 IS-Extended C2.01
Metric: 10 IS-Extended C1.02
IP Address: 192.168.0.4
Metric: 10 IP 10.0.0.4/30
Metric: 10 IP 10.0.0.8/30
Metric: 10 IP 10.0.0.32/30
Metric: 10 IP 192.168.0.4/32
IPv6 Address: 2001:DB8:B:0:1::6
Metric: 10 IPv6 2001:DB8:A:0:1:1:0:4/126
Metric: 10 IPv6 2001:DB8:A:0:1:1:0:8/126
Metric: 10 IPv6 2001:DB8:A:0:1:1:0:20/126
Metric: 10 IPv6 2001:DB8:B:0:1::6/128
The database shows that IPv6 prefixes in the default topology because there is no indication of multiple topology mode (MT-IPv6) next to IPv6 prefixes.
Step12: Configure multiple topology mode on the router C1 and C2:
C1(config)#router isis
C1(config-router)#address-family ipv6 unicast
C1(config-router-af)#multi-topology
!
C2(config)#router isis
C2(config-router)#address-family ipv6 unicast
C2(config-router-af)#multi-topology
After multi-topology mode has been enabled it should bring neighborship between routers D1 and C1 and router E1 and C2 back.
Step13: Verify if router D1 and E1 established neighborship with C routers:
D1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C1 L1 Gi0/2 10.0.0.5 UP 23 D1.02
!
E1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C2 L1 Gi0/2 10.0.0.37 UP 29 E1.02
Step14: Confirm connectivity between D2 and E2:
D2#ping 192.168.0.7 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.7, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.9
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/7/8 ms
D2#
The result is promising, IPv4 only part of topology able to communicate.
Step15: Verify detailed database on the router C1 to see what has been changed since multi-topology has been enabled:
C1#show isis database detail C1.00-00
IS-IS Level-1 LSP C1.00-00
LSPID LSP Seq Num LSP Checksum LSP Holdtime/Rcvd ATT/P/OL
C1.00-00 * 0x00000011 0xEE77 503/* 0/0/0
Area Address: 49.c000
NLPID: 0xCC 0x8E
Topology: IPv4 (0x0)
IPv6 (0x2)
Hostname: C1
Metric: 10 IS-Extended C2.01
Metric: 10 IS-Extended C1.02
Metric: 10 IS-Extended D1.02
Metric: 10 IS (MT-IPv6) C2.01
IP Address: 192.168.0.4
Metric: 10 IP 10.0.0.4/30
Metric: 10 IP 10.0.0.8/30
Metric: 10 IP 10.0.0.32/30
Metric: 10 IP 192.168.0.4/32
IPv6 Address: 2001:DB8:B:0:1::6
Metric: 10 IPv6 (MT-IPv6) 2001:DB8:A:0:1:1:0:4/126
Metric: 10 IPv6 (MT-IPv6) 2001:DB8:A:0:1:1:0:8/126
Metric: 10 IPv6 (MT-IPv6) 2001:DB8:A:0:1:1:0:20/126
Metric: 10 IPv6 (MT-IPv6) 2001:DB8:B:0:1::6/128
C1#
Presence of MT-IPv6 in the parenthesis next to IPv6 prefixes in the output shows that multiple topology mode has been enabled.
Step16: Confirm IPv4 connectivity between A2 and other L1 routers:
A2#ping 192.168.0.6
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.6, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 6/7/9 ms
A2#ping 192.168.0.9
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.9, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/5/7 ms
A2#ping 192.168.0.7
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.7, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 6/10/18 ms
A2#
Ping to B2, D2, and E2, confirms that IPv4 IS-IS topology configured properly, but what about IPv6?
Step17: Verify if A2 able to ping IPv6 address of B2:
A2#ping 2001:DB8:B:0:1::5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:B:0:1::5, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Not good! The current IPv6 connectivity issue is due to incomplete multi-topology mode implementation! router C1 and C2 have another IS-IS topology configured to run IPv6 while routers A1, A2, B1, and B2 still have their default topology configured for both IPv4 and IPv6.
Step18: Configure multi-topology mode on routers A1, A2, B1, and B2:
A1(config)#router isis
A1(config-router)#address-family ipv6
A1(config-router-af)#multi-topology
Repeat this for configuration for A2, B1, and B2 routers.
Step19: Verify IPv6 connectivity again between A2 and B2:
A2#ping 2001:DB8:b:0:1::5 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:B:0:1::5, timeout is 2 seconds:
Packet sent with a source address of 2001:DB8:B:0:1::3
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 6/6/9 ms
Great, now that IPv6 connectivity restored this lab is complete.
Summary:
Multiple topology mode is very useful when not all routers run the same routed protocols in the network, this lab shows you this feature within one L1 area, but you can experiment on your own what would happen to connectivity when it implemented in the L2 only area or in the hierarchical design with multiple areas L1 and L2 areas.
Download Lab: VIRL | EVE-NG | GNS3
Image requirements:
Cisco IOSv (vios-adventerprisek9-m.vmdk.SPA.156-2.T)
Introduction:
By default IS-IS protocol use single topology for all enabled routed protocols. If IS-IS runs in the dual-stack configuration, there would be only one link-state database for both IPv4 and IPv6 routed protocols. The problem with this implementation could arise if, in the L1 area, not all routers enabled for both IPv4 and IPV6, for example, if in this topology node A1 and A2 do not support IPV6 they will have trouble to communicate with the rest of the routers over IPV4 protocol. To fix this problem network topology have to be reconfigured to support multiple IS-IS topologies one for IPv4 which will be the default topology and another for IPv6, enabled under IPv6 address-family for IS-IS in the global router configuration. This lab introduces IS-IS multiple topology mode, learn how to configure and verify this technology.
Nodes Access:
Enable: cisco
Username: cisco
Password: cisco
Topology:
Original L1 IS-IS topology for both IPv4 and IPv6:
IPv4 and IPv6 addressing scheme:
The diagram shows how routed protocols implemented for this lab, some IS-IS routers route both IPv4 and IPv6 and others only operate IPv4:
Scenario:
As outlined in the third diagram, in the IS-IS L1 area C000 some routers will be configured to run both IPv4 and IPv6 and some only IPv4. This topology has been configured for IS-IS to route IPv4 networks. The goal of this lab is to configure IS-IS for IPv6 partially and observe how this configuration will break IP connectivity in the topology. Later, to fix communication between routers, multiple topology mode will be implemented.
Lab tasks:
1. Verify connectivity between routers in the topology.
2. Partially enable IS-IS to route IPv6.
3. Configure Multiple Topology Mode.
4. Verify the implementation of multi-topology mode.
Lab procedure:
Step1: Access CLI of router A2 and ping multiple IP addresses. Verify connectivity to B2, D2, and E2:
A2#ping 192.168.0.6 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.6, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.10
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/6 ms
A2#ping 192.168.0.9 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.9, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.10
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 3/3/5 ms
A2#ping 192.168.0.7 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.7, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.10
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/6/7 ms
A2#
Successful ping indicates that there are no connectivity issues in the topology.
Step2: Access CLI of router C1 and verify its IS-IS configuration:
C1#show isis protocol
IS-IS Router: <Null Tag>
System Id: 0000.0000.00C1.00 IS-Type: level-1
Manual area address(es):
49.c000
Routing for area address(es):
49.c000
Interfaces supported by IS-IS:
GigabitEthernet0/3 - IP
GigabitEthernet0/2 - IP
GigabitEthernet0/1 - IP
Loopback0 - IP
Redistribute:
static (on by default)
Distance for L2 CLNS routes: 110
RRR level: none
Generate narrow metrics: none
Accept narrow metrics: none
Generate wide metrics: level-1-2
Accept wide metrics: level-1-2
C1#
The output shows that IS-IS only enables for IPv4.
Step3: Configure IS-IS for IPv6 on router C1, enable it for the same interfaces as shown in the output above:
C1(config)#interface range g0/1-3, lo0
C1(config-if-range)#ipv6 router isis
C1(config-if-range)#end
C1#
Step4: Observe the problem caused by configuration in the step3:
*Jan 4 19:05:22.827: %SYS-5-CONFIG_I: Configured from console by console
*Jan 4 19:05:28.893: %CLNS-5-ADJCHANGE: ISIS: Adjacency to C2 (GigabitEthernet0/1) Down, hold time expired
*Jan 4 19:05:29.958: %CLNS-5-ADJCHANGE: ISIS: Adjacency to D1 (GigabitEthernet0/3) Down, hold time expired
*Jan 4 19:05:46.788: %CLNS-5-ADJCHANGE: ISIS: Adjacency to A1 (GigabitEthernet0/2) Down, hold time expired
C1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C1#
To bring adjacencies back up, neighbors of C1 have to be configured the same way as C1, run IS-IS for both IPv4 and IPv6.
Step5: Configure IS-IS for IPv6 on router C2:
C2(config)#interface range g0/1-3, lo0
C2(config-if-range)#ipv6 router isis
Step6: Verify that C2 has IS-IS neighborship with router C1:
C2#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C1 L1 Gi0/1 10.0.0.33 UP 24 C2.01
Step7: Configure IS-IS for IPv6 on routers A1 and A2:
A1(config)#interface range g0/1-2, lo0
A1(config-if-range)#ipv6 router isis
!
A2(config)#interface range g0/1, lo0
A2(config-if-range)#ipv6 router isis
Step8: Configure IS-IS for IPv6 on routers B1 and B2:
B1(config)#interface range g0/1-2, lo0
B1(config-if-range)#ipv6 router isis
!
B2(config)#interface range g0/1, lo0
B2(config-if-range)#ipv6 router isis
Step9: Verify IPv4 and IPv6 connectivity to router A2 from router B2:
B2#ping 192.168.0.10 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.10, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.6
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/6/9 ms
B2#ping 2001:DB8:B:0:1::3 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:B:0:1::3, timeout is 2 seconds:
Packet sent with a source address of 2001:DB8:B:0:1::5
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/5/6 ms
Both IPv4 and IPv6 connectivity confirmed.
Step10: Verify if router D2 able to ping router E2:
D2#ping 192.168.0.7
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.7, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Obviously, ping failed due to neighborship issue between routers C1 and D1, and routers C2 and E1, but D routers and E routers should not be enabled for IPv6 IS-IS, the fix for this problem is to configure multiple topology mode on the dual-stack enabled routers.
D1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C1 L1 Gi0/2 10.0.0.5 INIT 29 D1.02
D2 L1 Gi0/1 10.0.0.30 UP 8 D2.01
E1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C2 L1 Gi0/2 10.0.0.37 INIT 29 E1.02
E2 L1 Gi0/1 10.0.0.14 UP 24 E1.01
Both D1 and E1 shows that neighborship with C routers in the INIT state.
Step11: Before configuring multiple topology mode verify detail database on the dual-stack enabled nodes C1 and C2:
C1#show isis database detail C1.00-00
IS-IS Level-1 LSP C1.00-00
LSPID LSP Seq Num LSP Checksum LSP Holdtime/Rcvd ATT/P/OL
C1.00-00 * 0x0000000C 0xDE22 599/* 0/0/0
Area Address: 49.c000
NLPID: 0xCC 0x8E
Hostname: C1
Metric: 10 IS-Extended C2.01
Metric: 10 IS-Extended C1.02
IP Address: 192.168.0.4
Metric: 10 IP 10.0.0.4/30
Metric: 10 IP 10.0.0.8/30
Metric: 10 IP 10.0.0.32/30
Metric: 10 IP 192.168.0.4/32
IPv6 Address: 2001:DB8:B:0:1::6
Metric: 10 IPv6 2001:DB8:A:0:1:1:0:4/126
Metric: 10 IPv6 2001:DB8:A:0:1:1:0:8/126
Metric: 10 IPv6 2001:DB8:A:0:1:1:0:20/126
Metric: 10 IPv6 2001:DB8:B:0:1::6/128
The database shows that IPv6 prefixes in the default topology because there is no indication of multiple topology mode (MT-IPv6) next to IPv6 prefixes.
Step12: Configure multiple topology mode on the router C1 and C2:
C1(config)#router isis
C1(config-router)#address-family ipv6 unicast
C1(config-router-af)#multi-topology
!
C2(config)#router isis
C2(config-router)#address-family ipv6 unicast
C2(config-router-af)#multi-topology
After multi-topology mode has been enabled it should bring neighborship between routers D1 and C1 and router E1 and C2 back.
Step13: Verify if router D1 and E1 established neighborship with C routers:
D1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C1 L1 Gi0/2 10.0.0.5 UP 23 D1.02
!
E1#show isis neighbors
System Id Type Interface IP Address State Holdtime Circuit Id
C2 L1 Gi0/2 10.0.0.37 UP 29 E1.02
Step14: Confirm connectivity between D2 and E2:
D2#ping 192.168.0.7 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.7, timeout is 2 seconds:
Packet sent with a source address of 192.168.0.9
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/7/8 ms
D2#
The result is promising, IPv4 only part of topology able to communicate.
Step15: Verify detailed database on the router C1 to see what has been changed since multi-topology has been enabled:
C1#show isis database detail C1.00-00
IS-IS Level-1 LSP C1.00-00
LSPID LSP Seq Num LSP Checksum LSP Holdtime/Rcvd ATT/P/OL
C1.00-00 * 0x00000011 0xEE77 503/* 0/0/0
Area Address: 49.c000
NLPID: 0xCC 0x8E
Topology: IPv4 (0x0)
IPv6 (0x2)
Hostname: C1
Metric: 10 IS-Extended C2.01
Metric: 10 IS-Extended C1.02
Metric: 10 IS-Extended D1.02
Metric: 10 IS (MT-IPv6) C2.01
IP Address: 192.168.0.4
Metric: 10 IP 10.0.0.4/30
Metric: 10 IP 10.0.0.8/30
Metric: 10 IP 10.0.0.32/30
Metric: 10 IP 192.168.0.4/32
IPv6 Address: 2001:DB8:B:0:1::6
Metric: 10 IPv6 (MT-IPv6) 2001:DB8:A:0:1:1:0:4/126
Metric: 10 IPv6 (MT-IPv6) 2001:DB8:A:0:1:1:0:8/126
Metric: 10 IPv6 (MT-IPv6) 2001:DB8:A:0:1:1:0:20/126
Metric: 10 IPv6 (MT-IPv6) 2001:DB8:B:0:1::6/128
C1#
Presence of MT-IPv6 in the parenthesis next to IPv6 prefixes in the output shows that multiple topology mode has been enabled.
Step16: Confirm IPv4 connectivity between A2 and other L1 routers:
A2#ping 192.168.0.6
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.6, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 6/7/9 ms
A2#ping 192.168.0.9
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.9, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 5/5/7 ms
A2#ping 192.168.0.7
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.0.7, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 6/10/18 ms
A2#
Ping to B2, D2, and E2, confirms that IPv4 IS-IS topology configured properly, but what about IPv6?
Step17: Verify if A2 able to ping IPv6 address of B2:
A2#ping 2001:DB8:B:0:1::5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:B:0:1::5, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Not good! The current IPv6 connectivity issue is due to incomplete multi-topology mode implementation! router C1 and C2 have another IS-IS topology configured to run IPv6 while routers A1, A2, B1, and B2 still have their default topology configured for both IPv4 and IPv6.
Step18: Configure multi-topology mode on routers A1, A2, B1, and B2:
A1(config)#router isis
A1(config-router)#address-family ipv6
A1(config-router-af)#multi-topology
Repeat this for configuration for A2, B1, and B2 routers.
Step19: Verify IPv6 connectivity again between A2 and B2:
A2#ping 2001:DB8:b:0:1::5 source lo0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:B:0:1::5, timeout is 2 seconds:
Packet sent with a source address of 2001:DB8:B:0:1::3
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 6/6/9 ms
Great, now that IPv6 connectivity restored this lab is complete.
Summary:
Multiple topology mode is very useful when not all routers run the same routed protocols in the network, this lab shows you this feature within one L1 area, but you can experiment on your own what would happen to connectivity when it implemented in the L2 only area or in the hierarchical design with multiple areas L1 and L2 areas.
Comments
Post a Comment