IP Router Configuration Command Reference
106 Router Configuration Guide
BGP prefix with a BGP next-hop resolved to a static route which itself resolves to set of tunnel next-
hops towards an indirect next-hop in RTM or TTM.
BGP prefix resolving to another BGP prefix which next-hop is resolved to set of ECMP tunnel next-
hops with a static route in RTM or TTM or to IGP shortcuts in RTM.
IGP computes the normalized weight for each prefix tunnel next-hop. IGP updates the route in RTM
with the set of tunnel next-hops and normalized weights. RTM downloads the information to IOM for
inclusion in the FIB.
If one or more LSPs in the ECMP set of a prefix do not have a weight configured, the regular ECMP
spraying for the prefix will be performed.
The weight assigned to an LSP impacts only the forwarding decision, not the routing decision. In other
words, it does not change the selection of the set of ECMP tunnel next-hops of a prefix when more
next-hops exist than the value of the router ecmp option. Once the set of tunnel next-hops is selected,
the LSP weight is used to modulate the amount of packets forwarded over each next-hop. It also does
not change the hash routine, but only the spraying of the flows over the tunnel next-hops is modified
to reflect the normalized weight of each tunnel next-hop.
The no version of the command resumes regular ECMP spraying of packets of IGP, BGP, and static
route prefixes over MPLS LSP.
fib-priority
Syntax fib-priority {high | standard}
Context config>router
Description This command specifies the FIB priority for VPRN.
icmp-tunneling
Syntax icmp-tunneling
no icmp-tunneling
Context config>router
Description This command enables the tunneling of ICMP reply packets over MPLS LSP at a LSR node as per
RFC 3032.
The LSR part of this feature consists of crafting the reply ICMP packet of type=11- 'time exceeded',
with a source address set to a local address of the LSR node, and appending the IP header and leading
payload octets of the original datagram. The system skips the lookup of the source address of the
sender of the label TTL expiry packet, which becomes the destination address of the ICMP reply
packet. Instead, CPM injects the ICMP reply packet in the forward direction of the MPLS LSP the label
TTL expiry packet was received from. The TTL of pushed labels should be set to 255.
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