MPLS CHAPTER 2
QUESTIONS:
4. What protocol(s)/Port(s) are used for LDP Hellos & Sessions ?
5. How does R3 know what R2's local label is for a specific network ?
6. When MPLS is enabled, what would prevent an LDP neighborship ?
7. Why would you use an ACL in combination with an MPLS debug ?
SOLUTIONS :
4. What protocol(s)/Port(s) are used for LDP Hellos & Sessions ?
5. How does R3 know what R2's local label is for a specific network ?
7. Why would you use an ACL in combination with an MPLS debug ?
1. first they send hello pkts to discover the lsp routers with udp multicast 646 224.0.0.2
2. then the establish tcp relationship with tcp 646 224.0.0.2 , higher rid will act like
active router lower rid will act like passive router.
3. then they send & recieve ldp lables
DIAGRAM :
in the diagram given from the last lab , disable & enable mpls & find the neighbor relationship .
configure on R2 for the relationship with R3
conf)# access-list 1 permit 3.3.3.3
exit
# debug mpls ldp bindings prefix-list 1
R2(config)#access-list 1 permit 3.3.3.3
R2(config)#end
R2#debug mpls ldp bindings prefix-acl 1
LDP Label Information Base (LIB) changes debugging is on for prefix ACL 1
R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#no mpls ip
*Mar 1 00:06:42.475: tagcon: tibent(3.3.3.3/32): deleted
R2(config)#mpls ip
R2(config)#
-----output cut -----------
*Mar 1 00:06:44.827: tib: find route tags: 3.3.3.3/32, Fa0/1, nh 10.1.23.3, res nh 10.1.23.3
*Mar 1 00:06:44.827: tagcon: announce labels for: 3.3.3.3/32; nh 10.1.23.3, Fa0/1, inlabel 19, outlabel unknown (from 0.0.0.0:0), find route tags
R2(config)#
*Mar 1 00:06:49.907: tagcon: (Default-IP-Routing-Table) Assign peer id; 3.3.3.3:0: id 0
*Mar 1 00:06:49.911: %LDP-5-NBRCHG: LDP Neighbor 3.3.3.3:0 (1) is UP
*Mar 1 00:06:49.927: tagcon: 3.3.3.3:0: 10.1.23.3 added to addr<->ldp ident map
*Mar 1 00:06:49.931: tagcon: 3.3.3.3:0: 3.3.3.3 added to addr<->ldp ident map
*Mar 1 00:06:49.931: tagcon: tibent(3.3.3.3/32): label imp-null from 3.3.3.3:0 added
*Mar 1 00:06:49.935: tagcon: announce labels for: 3.3.3.3/32; nh 10.1.23.3, Fa0/1, inlabel 19, outlabel imp-null (from 3.3.3.3:0), add rem binding
*Mar 1 00:06:50.367: tagcon: (Default-IP-Routing-Table) Assign peer id; 1.1.1.1:0: id 1
*Mar 1 00:06:50.371: %LDP-5-NBRCHG: LDP Neighbor 1.1.1.1:0 (2) is UP
R2(config)#
*Mar 1 00:06:50.479: tagcon: 1.1.1.1:0: 10.1.12.1 added to addr<->ldp ident map
*Mar 1 00:06:50.483: tagcon: 1.1.1.1:0: 1.1.1.1 added to addr<->ldp ident map
*Mar 1 00:06:50.491: tagcon: tibent(3.3.3.3/32): label 502 from 1.1.1.1:0 added
*Mar 1 00:06:50.491: tib: Not OK to announce label; nh 10.1.23.3 not bound to 1.1.1.1:0
*Mar 1 00:06:50.495: tagcon: omit announce labels for: 3.3.3.3/32; nh 10.1.23.3, Fa0/1, from 1.1.1.1:0: add rem binding: next hop = 10.1.23.3
R2#undebug all
6. When MPLS is enabled, what would prevent an LDP neighborship ?
# sh mpls ldp neighbour
if transport address in not reachable they will not form ldp relationships
R2#sh mpls ldp neighbor
Peer LDP Ident: 1.1.1.1:0; Local LDP Ident 2.2.2.2:0
TCP connection: 1.1.1.1.646 - 2.2.2.2.38184
State: Oper; Msgs sent/rcvd: 19/19; Downstream
Up time: 00:10:11
LDP discovery sources:
FastEthernet0/0, Src IP addr: 10.1.12.1
Addresses bound to peer LDP Ident:
10.1.12.1 1.1.1.1
Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 2.2.2.2:0
TCP connection: 3.3.3.3.43683 - 2.2.2.2.646
State: Oper; Msgs sent/rcvd: 13/13; Downstream
Up time: 00:04:38
LDP discovery sources:
FastEthernet0/1, Src IP addr: 10.1.23.3
Addresses bound to peer LDP Ident:
10.1.23.3 3.3.3.3
R2#sh mpls ldp bindings local
tib entry: 1.1.1.1/32, rev 2
local binding: tag: 18
tib entry: 2.2.2.2/32, rev 4
local binding: tag: imp-null
tib entry: 3.3.3.3/32, rev 6
local binding: tag: 19
tib entry: 10.1.12.0/24, rev 8
local binding: tag: imp-null
tib entry: 10.1.23.0/24, rev 10
local binding: tag: imp-null
R2#sh ip cef 3.3.3.3
3.3.3.3/32, version 21, epoch 0, cached adjacency 10.1.23.3
0 packets, 0 bytes
tag information set
local tag: 19
via 10.1.23.3, FastEthernet0/1, 0 dependencies
next hop 10.1.23.3, FastEthernet0/1
valid cached adjacency
tag rewrite with Fa0/1, 10.1.23.3, tags imposed: {}
R2#sh ip route 3.3.3.3
Routing entry for 3.3.3.3/32
Known via "ospf 1", distance 110, metric 11, type intra area
Last update from 10.1.23.3 on FastEthernet0/1, 00:17:24 ago
Routing Descriptor Blocks:
* 10.1.23.3, from 3.3.3.3, 00:17:24 ago, via FastEthernet0/1
Route metric is 11, traffic share count is 1
++++>> let us change the next hop of R2 for loopback address 3.3.3.3
R2(config)#ip route 3.3.3.3 255.255.255.255 10.1.12.1
R2(config)#end
R2# ship
*Mar 1 00:20:15.535: %SYS-5-CONFIG_I: Configured from console by consol
R2# sh ip route
Codes: 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
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/11] via 10.1.12.1, 00:19:09, FastEthernet0/0
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback1
3.0.0.0/32 is subnetted, 1 subnets
S 3.3.3.3 [1/0] via 10.1.12.1
10.0.0.0/24 is subnetted, 2 subnets
C 10.1.12.0 is directly connected, FastEthernet0/0
C 10.1.23.0 is directly connected, FastEthernet0/1
R2#traceroute 3.3.3.3 source 2.2.2.2
Type escape sequence to abort.
Tracing the route to 3.3.3.3
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
you can see it is unreachable plus the bytes tag switched is very high 846612 ???
means packet is looping in the network.
R2#sh mpls forwarding-table 3.3.3.3
Local Outgoing Prefix Bytes tag Outgoing Next Hop
tag tag or VC or Tunnel Id switched interface
19 502 3.3.3.3/32 846612 Fa0/0 10.1.12.1
but reachable next hop is 10.1.23.3
so it will not form neighbour:
redo the static route and it will work:
on R2 : no ip route 3.3.3.3 255.255.255.255 10.1.12.1
it will form neighbour
R2(config)#no ip route 3.3.3.3 255.255.255.255 10.1.12.1
R2(config)#end
R2#ping
*Mar 1 00:23:25.963: %SYS-5-CONFIG_I: Configured from console by console
R2#ping 3.3.3.3 so 2.2.2.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
Packet sent with a source address of 2.2.2.2
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/29/48 ms
R2#
*Mar 1 00:23:35.419: %LDP-5-NBRCHG: LDP Neighbor 3.3.3.3:0 (1) is UP
QUESTIONS:
4. What protocol(s)/Port(s) are used for LDP Hellos & Sessions ?
5. How does R3 know what R2's local label is for a specific network ?
6. When MPLS is enabled, what would prevent an LDP neighborship ?
7. Why would you use an ACL in combination with an MPLS debug ?
SOLUTIONS :
4. What protocol(s)/Port(s) are used for LDP Hellos & Sessions ?
5. How does R3 know what R2's local label is for a specific network ?
7. Why would you use an ACL in combination with an MPLS debug ?
1. first they send hello pkts to discover the lsp routers with udp multicast 646 224.0.0.2
2. then the establish tcp relationship with tcp 646 224.0.0.2 , higher rid will act like
active router lower rid will act like passive router.
3. then they send & recieve ldp lables
DIAGRAM :
in the diagram given from the last lab , disable & enable mpls & find the neighbor relationship .
configure on R2 for the relationship with R3
conf)# access-list 1 permit 3.3.3.3
exit
# debug mpls ldp bindings prefix-list 1
R2(config)#access-list 1 permit 3.3.3.3
R2(config)#end
R2#debug mpls ldp bindings prefix-acl 1
LDP Label Information Base (LIB) changes debugging is on for prefix ACL 1
R2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)#no mpls ip
*Mar 1 00:06:42.475: tagcon: tibent(3.3.3.3/32): deleted
R2(config)#mpls ip
R2(config)#
-----output cut -----------
*Mar 1 00:06:44.827: tib: find route tags: 3.3.3.3/32, Fa0/1, nh 10.1.23.3, res nh 10.1.23.3
*Mar 1 00:06:44.827: tagcon: announce labels for: 3.3.3.3/32; nh 10.1.23.3, Fa0/1, inlabel 19, outlabel unknown (from 0.0.0.0:0), find route tags
R2(config)#
*Mar 1 00:06:49.907: tagcon: (Default-IP-Routing-Table) Assign peer id; 3.3.3.3:0: id 0
*Mar 1 00:06:49.911: %LDP-5-NBRCHG: LDP Neighbor 3.3.3.3:0 (1) is UP
*Mar 1 00:06:49.927: tagcon: 3.3.3.3:0: 10.1.23.3 added to addr<->ldp ident map
*Mar 1 00:06:49.931: tagcon: 3.3.3.3:0: 3.3.3.3 added to addr<->ldp ident map
*Mar 1 00:06:49.931: tagcon: tibent(3.3.3.3/32): label imp-null from 3.3.3.3:0 added
*Mar 1 00:06:49.935: tagcon: announce labels for: 3.3.3.3/32; nh 10.1.23.3, Fa0/1, inlabel 19, outlabel imp-null (from 3.3.3.3:0), add rem binding
*Mar 1 00:06:50.367: tagcon: (Default-IP-Routing-Table) Assign peer id; 1.1.1.1:0: id 1
*Mar 1 00:06:50.371: %LDP-5-NBRCHG: LDP Neighbor 1.1.1.1:0 (2) is UP
R2(config)#
*Mar 1 00:06:50.479: tagcon: 1.1.1.1:0: 10.1.12.1 added to addr<->ldp ident map
*Mar 1 00:06:50.483: tagcon: 1.1.1.1:0: 1.1.1.1 added to addr<->ldp ident map
*Mar 1 00:06:50.491: tagcon: tibent(3.3.3.3/32): label 502 from 1.1.1.1:0 added
*Mar 1 00:06:50.491: tib: Not OK to announce label; nh 10.1.23.3 not bound to 1.1.1.1:0
*Mar 1 00:06:50.495: tagcon: omit announce labels for: 3.3.3.3/32; nh 10.1.23.3, Fa0/1, from 1.1.1.1:0: add rem binding: next hop = 10.1.23.3
R2#undebug all
6. When MPLS is enabled, what would prevent an LDP neighborship ?
# sh mpls ldp neighbour
if transport address in not reachable they will not form ldp relationships
R2#sh mpls ldp neighbor
Peer LDP Ident: 1.1.1.1:0; Local LDP Ident 2.2.2.2:0
TCP connection: 1.1.1.1.646 - 2.2.2.2.38184
State: Oper; Msgs sent/rcvd: 19/19; Downstream
Up time: 00:10:11
LDP discovery sources:
FastEthernet0/0, Src IP addr: 10.1.12.1
Addresses bound to peer LDP Ident:
10.1.12.1 1.1.1.1
Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 2.2.2.2:0
TCP connection: 3.3.3.3.43683 - 2.2.2.2.646
State: Oper; Msgs sent/rcvd: 13/13; Downstream
Up time: 00:04:38
LDP discovery sources:
FastEthernet0/1, Src IP addr: 10.1.23.3
Addresses bound to peer LDP Ident:
10.1.23.3 3.3.3.3
R2#sh mpls ldp bindings local
tib entry: 1.1.1.1/32, rev 2
local binding: tag: 18
tib entry: 2.2.2.2/32, rev 4
local binding: tag: imp-null
tib entry: 3.3.3.3/32, rev 6
local binding: tag: 19
tib entry: 10.1.12.0/24, rev 8
local binding: tag: imp-null
tib entry: 10.1.23.0/24, rev 10
local binding: tag: imp-null
R2#sh ip cef 3.3.3.3
3.3.3.3/32, version 21, epoch 0, cached adjacency 10.1.23.3
0 packets, 0 bytes
tag information set
local tag: 19
via 10.1.23.3, FastEthernet0/1, 0 dependencies
next hop 10.1.23.3, FastEthernet0/1
valid cached adjacency
tag rewrite with Fa0/1, 10.1.23.3, tags imposed: {}
R2#sh ip route 3.3.3.3
Routing entry for 3.3.3.3/32
Known via "ospf 1", distance 110, metric 11, type intra area
Last update from 10.1.23.3 on FastEthernet0/1, 00:17:24 ago
Routing Descriptor Blocks:
* 10.1.23.3, from 3.3.3.3, 00:17:24 ago, via FastEthernet0/1
Route metric is 11, traffic share count is 1
++++>> let us change the next hop of R2 for loopback address 3.3.3.3
R2(config)#ip route 3.3.3.3 255.255.255.255 10.1.12.1
R2(config)#end
R2# ship
*Mar 1 00:20:15.535: %SYS-5-CONFIG_I: Configured from console by consol
R2# sh ip route
Codes: 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
Gateway of last resort is not set
1.0.0.0/32 is subnetted, 1 subnets
O 1.1.1.1 [110/11] via 10.1.12.1, 00:19:09, FastEthernet0/0
2.0.0.0/32 is subnetted, 1 subnets
C 2.2.2.2 is directly connected, Loopback1
3.0.0.0/32 is subnetted, 1 subnets
S 3.3.3.3 [1/0] via 10.1.12.1
10.0.0.0/24 is subnetted, 2 subnets
C 10.1.12.0 is directly connected, FastEthernet0/0
C 10.1.23.0 is directly connected, FastEthernet0/1
R2#traceroute 3.3.3.3 source 2.2.2.2
Type escape sequence to abort.
Tracing the route to 3.3.3.3
1 * * *
2 * * *
3 * * *
4 * * *
5 * * *
you can see it is unreachable plus the bytes tag switched is very high 846612 ???
means packet is looping in the network.
R2#sh mpls forwarding-table 3.3.3.3
Local Outgoing Prefix Bytes tag Outgoing Next Hop
tag tag or VC or Tunnel Id switched interface
19 502 3.3.3.3/32 846612 Fa0/0 10.1.12.1
but reachable next hop is 10.1.23.3
so it will not form neighbour:
redo the static route and it will work:
on R2 : no ip route 3.3.3.3 255.255.255.255 10.1.12.1
it will form neighbour
R2(config)#no ip route 3.3.3.3 255.255.255.255 10.1.12.1
R2(config)#end
R2#ping
*Mar 1 00:23:25.963: %SYS-5-CONFIG_I: Configured from console by console
R2#ping 3.3.3.3 so 2.2.2.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
Packet sent with a source address of 2.2.2.2
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/29/48 ms
R2#
*Mar 1 00:23:35.419: %LDP-5-NBRCHG: LDP Neighbor 3.3.3.3:0 (1) is UP
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