Cisco's BroadWorks tech note says routers commonly block fragmented UDP because they must buffer fragments until the whole message arrives, which attackers can exploit to exhaust memory.
Checked 2026-10-02
- Vendor
- Cisco
- Product
- Cisco BroadWorks
- Subsystem
- SIP transport
- Deployment
- on-premises
- Region
- not restricted
- Release range
- as of 2020-11-11 document update
- Checked
- 2026-10-02
Sources
- Working with large SIP packets — Cisco Systems · tier 2 current vendor documentation · Problem section
Cite this note
APA
WarmTransfer. (2026, October 2). Troubleshooting failed calls caused by large SIP messages over UDP: source note sip-fragmentation-troubleshooting-bw-routers-drop-udp-frags. WarmTransfer. https://warmtransfer.net/knowledge/claims/sip-fragmentation-troubleshooting-bw-routers-drop-udp-frags
BibTeX
@misc{warmtransfer-claim-sip-fragmentation-troubleshooting-bw-routers-drop-udp-frags,
title = {Troubleshooting failed calls caused by large SIP messages over UDP: source note sip-fragmentation-troubleshooting-bw-routers-drop-udp-frags},
author = {{WarmTransfer}},
year = {2026},
url = {https://warmtransfer.net/knowledge/claims/sip-fragmentation-troubleshooting-bw-routers-drop-udp-frags},
note = {Source note sip-fragmentation-troubleshooting-bw-routers-drop-udp-frags, checked 2026-10-02}
}