Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 237)

Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide 213
53-1003031-02
IP Traceroute over MPLS
1
Scenario B - Layer 3 VPN over MPLS
MPLS is enabled in the provider core. Customer traffic is routed through the provider network using
a Layer 3 VPN. The egress PE is a Brocade NetIron CER or a Brocade NetIron CES.
1. Issue the ip icmp mpls-response command with the use-lsp option on each LSR (R1, R2, R3,
and R4).
Brocade# configure terminal
Brocade(config)# ip icmp mpls-response use-lsp
2. On the CE 1 (IP address 10.3.3.3), issue the traceroute command with the destination address
of CE2 (IP address 10.1.3.8).
CE1# traceroute 10.1.3.8
Type Control-c to abort
Tracing the route to IP node (10.1.3.8) from 1 to 30 hops
1 <1 ms <1 ms <1 ms 10.51.3.7
2 <1 ms <1 ms <1 ms 10.56.1.2
MPLS Label=1048 Exp=7 TTL=1 S=0
MPLS Label=500000 Exp=7 TTL=1 S=1
3 <1 ms <1 ms <1 ms 10.52.10.4
MPLS Label=1026 Exp=7 TTL=1 S=0
MPLS Label=500000 Exp=7 TTL=1 S=1
4 <1 ms <1 ms <1 ms 10.34.22.8
5 <1 ms <1 ms <1 ms 10.1.3.8
In a Layer 3 VPN network, ICMP responses can only be forwarded as labeled MPLS packets along
configured LSPs. Traceroute operates as described in section “
“Tracing a route through an MPLS
domain” , reporting both the outer path label and the VPN label used to route the packets to the
appropriate VRF interface.
Tracing a route across an MPLS domain without label stack extensions and
use-lsp disabled
Assumptions: The MPLS response default configuration is enabled on all LSRs in the provider
network and the user wants to troubleshoot the IP routes. the user does not care about labels and
the user configures traceroute to suppress label stack information. CE1 is sending a traceroute to
CE2 with a destination IP address of 10.1.3.8. ICMP messages are generated without label stack
extensions and forwarded per IP routing table lookup.
Scenario A - IP over MPLS
IP over MPLS (IPoMPLS) is enabled in the provider core.
1. Issue the ip icmp mpls-response command with the no-label-extension option on each LSR
(R1, R2, R3, and R4).
Brocade# configure terminal
Brocade(config)#ip icmp mpls-response no-label-extension
2. On the CE 1 (IP address 10.3.3.3), issue the traceroute command with the destination address
of CE2 (IP address 10.1.3.8).
CE1# traceroute 10.1.3.8
Type Control-c to abort
Tracing the route to IP node (10.1.3.8) from 1 to 30 hops