The Cisco Multicast Source Discovery Protocol (MSDP) router must be configured to limit the amount of source-active messages it accepts on a per-peer basis.

Severity
Group ID
Group Title
Version
Rule ID
Date
STIG Version
lowV-216822SRG-NET-000018-RTR-000009CISC-RT-000940SV-216822r1117236_rule2025-08-193

Description

To reduce any risk of a denial-of-service (DoS) attack from a rogue or misconfigured MSDP router, the router must be configured to limit the number of source-active messages it accepts from each peer.

ℹ️ Check

Review the router configuration to determine if it is configured to limit the amount of source-active messages it accepts on a per-peer basis. router msdp … … … peer 4.4.4.4 remote-as 33 maximum external-sa 555 ! peer 5.5.5.5 remote-as 44 maximum external-sa 555 ! ! If the router is not configured to limit the source-active messages it accepts, this is a finding.

✔️ Fix

Configure the router to limit the amount of source-active messages it accepts from each peer. RP/0/0/CPU0:R2(config)#router msdp RP/0/0/CPU0:R2(config-msdp)#peer x.14.2.1 RP/0/0/CPU0:R2(config-msdp-peer)#maximum external-sa nnn RP/0/0/CPU0:R2(config-msdp-peer)#exit RP/0/0/CPU0:R2(config-msdp)#peer x.15.3.5 RP/0/0/CPU0:R2(config-msdp-peer)#maximum external-sa nnn RP/0/0/CPU0:R2(config-msdp-peer)#end