Configuring L2Tpv3 Control Message Hashing - Cisco CRS Configuration Manual

Configuring L2TP Control-Channel Parameters
Step 5
hostname name
Example:
RP/0/RP0/CPU0:router(config-l2tp-class)# hostname yb2
Specifies a hostname used to identify the router during L2TP control-channel authentication.
• If you do not use this command, the default hostname of the router is used.

Configuring L2TPv3 Control Message Hashing

Perform this task to configure L2TPv3 Control Message Hashing feature for an L2TP class.
L2TPv3 control message hashing incorporates authentication or integrity check for all control messages. This
per-message authentication is designed to guard against control message spoofing and replay attacks that
would otherwise be trivial to mount against the network.
Enabling the L2TPv3Control Message Hashing feature will impact performance during control-channel and
session establishment because additional digest calculation of the full message content is required for each
sent and received control message. This is an expected trade-off for the additional security afforded by this
feature. In addition, network congestion may occur if the receive window size is too small. If the L2TPv3
Control Message Hashing feature is enabled, message digest validation must be enabled. Message digest
validation deactivates the data path received sequence number update and restricts the minimum local receive
window size to 35.
You can configure control-channel authentication or control message integrity checking; however,
control-channel authentication requires participation by both peers, and a shared secret must be configured
on both routers. Control message integrity check is unidirectional, and requires configuration on only one of
the peers.
SUMMARY STEPS
1. configure
2. l2tp-class word
3. digest { check disable | hash { MD5 | SHA1 } ] | secret { 0 | 7 } password ]
4. hidden
DETAILED STEPS
Step 1
configure
Example:
RP/0/RP0/CPU0:router# configure
Enters the Global Configuration mode.
Step 2 l2tp-class word
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
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Implementing Layer 2 Tunnel Protocol Version 3