Creating Static LSPs

Static LSPs are label switched paths that are manually configured at each LSR in the prospective path. Static LSPs are too labor intensive for building complex network topologies, but they can be useful for defining simple one-hop LSPs to MTUs that might not have the CPU power necessary to support routing and label distribution protocols.

Static LSP Example shows two static LSPs configured between VLAN A and VLAN B. The dashed line shows the static LSP for unidirectional communications from VLAN A to VLAN B. The solid line shows the static LSP for communications in the reverse direction.

Static LSP Example

The path that an LSP takes and the labels the LSP uses at every hop do not change when the network topology changes due to links and nodes going up or down. Once enabled, a static LSP remains administratively up until it is manually disabled.

Static LSP configuration is different for ingress, transit, and egress LSRs. At the ingress LER, only an egress label is defined. At transit LSRs, both ingress and egress labels must be defined, and at the egress LER, only the ingress label is defined. During configuration, you must ensure that the egress label number for each LSR matches the ingress label number for the downstream LSR.

When creating static LSPs, consider the following guidelines:

It is your responsibility to ensure that the egress label of an LSR matches the ingress label of the downstream LSR. The software does not detect or report label mismatches. Mismatches result in dropped or mis-routed packets.
The operational state of the LSP is set to down at the head-end on local failures. However, there is no mechanism to detect the LSP going down when a failure occurs on a downstream node. When a failure occurs at a downstream node, traffic may be black-holed for the duration of the failure.
The traffic profile for static LSPs is not configurable in this release. All static LSPs are given best effort treatment.
The maximum number of static LSPs configurable on any given node is 1024. The maximum number of ingress static LSPs that are used to forward traffic to a single destination is 16 (as limited by ECMP (Equal Cost Multi Paths)).
When multiple LSPs exist for the same destination, unless forced otherwise, signaled LSPs are preferred to static LSPs. When choosing an LSP for a FEC, the software prefers RSVP-TE LSPs first, LDP next, and finally static LSPs.
Since the software has no knowledge of the cost or hop-count associated with each static LSP, all static LSPs to the same destination are equally preferred by IP routing.
We recommend that the same LSP name be used on every LSR along the path of the static LSP. The software does not check for naming consistency across LSRs. However the switch does report an error when the configured name is not unique to the LSP on that LSR.

To configure a static LSP, use the following procedure at each node on the path:

Create a namespace for the LSP using the following command:
create mpls static lsp lsp_name destination ipaddress
Configure the appropriate labels for the LSP using the following command:
configure mpls static lsp lsp_name [{egress [egress_label | implicit-null] egress-vlan evlan_name next-hop ipaddress} {ingress ingress_label {ingress-vlan ivlan_name}}]
Configure optional traffic restrictions for IP or VPN traffic as needed using the following command:
configure mpls static lsp lsp_name transport [ip-traffic [allow | deny] | vpn-traffic [allow {all | assigned-only} | deny]]
Enable the static LSP for operation using the following command:
enable mpls static lsp {lsp_name | all }
When the configuration is complete, you can view the static LSP configuration with the following command:
show mpls static lsp {summary | {lsp_name} {detail}}
Clear the counters for the static LSP using the command:
clear counters mpls static lsp {lsp_name | all }
Once the static LSP is created on all path nodes, you can configure a default route, an IP route, or a VPN route to use the LSP. To configure a default or IP route to use the LSP, use the following command:
configure iproute add default [{gateway {metric} {vr vr_name} {unicast-only | multicast-only}} | {lsp lsp_name {metric}}]
To configure a VPN route to use the LSP, use the following command:
configure l2vpn [vpls vpls_name | vpws vpws_name] peer ipaddress [add | delete] mpls lsp lsp_name
To disable a static LSP, use the following command:
disable mpls static lsp {lsp_name | all }
To delete a static LSP, use the following command:
delete mpls static lsp [lsp_name | all]

Published March 2020prev | next

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