next-hop-mpls

Configures BGP shortcuts using next-hop MPLS to force BGP to use an MPLS tunnel as the preferred route to a destination network when an MPLS LSP tunnel is available.

Syntax

next-hop-mpls [ compare-lsp-metric | follow-igp ]

no next-hop-mpls [ compare-lsp-metric | follow-igp ]

Command Default

BGP uses the default BGP decision process and native IP forwarding to build BGP EMCP routes. Only IP routing tables are used to resolve routes for the routing table.

Parameters

compare-lsp-metric: Enables BGP to compare the configured LSP metrics as the IGP cost for the next hop.

follow-igp: Ignores the MPLS metric cost in the BGP decision process and uses the IGP cost. BGP checks when an MPLS LSP is present, and totally ignores the LSP metric.

Modes

BGP address-family IPv4 unicast configuration mode

Usage Guidelines

When the next-hop-mpls command is enabled without either option, BGP sets the LSP metrics to one.

Enabling or disabling an option takes effect immediately. BGP automatically recalculates the existing BGP routes.

The compare-lsp-metric and follow-igp options are mutually exclusive.

When the compare-lsp-metric option is configured and you change the LSP metric, the routing table is updated.

Use the no form of the command to disable global next-hop MPLS.

When you use the no form of the command with the compare-lsp-metric or follow-igp option, all LSP metrics become equal cost. However, global next-hop MPLS remains enabled.

For the follow-igp option, consider the following:

When you are running IGP throughout the network, and the IGP metric is trusted in the entire domain, you may want to rely on this IGP metric to make a best path and forwarding decision, regardless of whether the forwarding happens in native IP or MPLS encapsulation.
The MPLS metric is manually configured in each LSP. There is no dynamic way to tie MPLS metric with an IGP metric. When using MPLS LSP as a BGP route outgoing interface, you loses the ability to tie the forwarding decision with a unified IGP metric.
When combined with the BGP install-igp-cost command, you can change the route cost from BGP MED to IGP cost and is used when BGP routes are added to the RTM.
When combined with a BGP outbound policy for route set metric-type internal command, you can set Layer-3 VPN and IP over MPLS routes using IGP metric to send out as the BGP MED value.

MPLS is supported on the Extreme 8820, SLX 9740, SLX 9640, and SLX 9540 devices only.

Examples

The following example enables BGP shortcuts through next-hop MPLS and BGP to set the next hop IGP cost to one instead of the actual LSP metric.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# address-family ipv4 unicast
device(config-bgp-ipv4u)# next-hop-mpls

The following example enables BGP shortcuts through next-hop MPLS and BGP to use the configured LSP metrics as the IGP cost for the next hop.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# address-family ipv4 unicast
device(config-bgp-ipv4u)# next-hop-mpls compare-lsp-metric

The following example enables BGP shortcuts through next-hop MPLS and BGP to ignore the LSP metrics and to use the IGP cost for the next hop.

device# configure terminal
device(config)# router bgp
device(config-bgp-router)# address-family ipv4 unicast
device(config-bgp-ipv4u)# next-hop-mpls follow-igp