7705 SAR Interfaces
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Interface Configuration Guide
3HE 11011 AAAC TQZZA Edition: 01
3.2.14.5 TEID Hashing for GTP-encapsulated Traffic
GTP is the GPRS (general packet radio service) tunneling protocol. The tunnel
endpoint identifier (TEID) is a field in the GTP header. TEID hashing can be enabled
on Layer 3 interfaces. The hash algorithm identifies the GTP-U protocol by checking
the UDP destination port (2152) of an IP packet to be hashed. If the value of the port
matches, the packet is assumed to be GTP-U. For GTPv1 packets, the TEID value
from the expected header location is then included in the hash. For GTPv2 packets,
the TEID flag value in the expected header is additionally checked to verify whether
the TEID is present. If the TEID is present, it is included in the hash algorithm inputs.
TEID load balancing is configured at the router interface level using the config>
router>if>teid-load-balancing command. It can also be configured at the IES or
VPRN service interface level.
For LSR LDP ECMP, TEID load balancing is configured using the lbl-ip-l4-teid
option in the lsr-load-balancing command at the system level or router interface
level. Configuration at the router interface level overrides the system-level
configuration for the specified interface.
TEID load balancing can also be configured at the service level for Epipe and VPLS
services. TEID load balancing at the service level is not impacted by TEID load
balancing at the router interface or service interface levels.
3.2.14.6 Entropy Labels
The 7705 SAR supports MPLS entropy labels on RSVP-TE LSPs, as per RFC 6790.
The entropy label provides greater granularity for load balancing on an LSR where
load balancing is typically based on the MPLS label stack.
If an ELI is found in the label stack, the entropy label is used as the hash result and
hashing continues based on the configuration of label-only (lbl-only) or label-IP
(lbl-ip) options. For information on the behavior of LSR hashing when entropy label
is enabled, see LSR Hashing.
To support entropy labels on RSVP-TE LSPs:
• the eLER must signal to the ingress node that entropy label capability is enabled,
meaning that it (the eLER) can receive and process an entropy label for an LSP
tunnel. Entropy labels are supported on RSVP-TE tunnels. Entropy labels are
not supported on point-to-multipoint LSPs, BGP tunnels, or LDP FECs.
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