Difference between revisions of "Troubleshoot"
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− | == MTU | + | == "Not working" network == |
+ | *Duplex | ||
+ | *Cable | ||
+ | *Firewall - disable it | ||
+ | *DNS filtering - public DNS | ||
+ | *ISP outage - ping its address | ||
+ | *Path outage - MTR tool | ||
+ | *ARP old record | ||
+ | *MAC collision | ||
+ | *STP loop/Broadcast storm | ||
+ | *Route missing | ||
+ | *LACP/PAGP must be on both ends configured | ||
+ | *Zombie process and station or froze | ||
+ | *Local firewall on device, or network type (windows-public) | ||
+ | *NAT | ||
+ | *Cache browser - try incognito mode | ||
+ | |||
+ | == Slow network == | ||
+ | *Path drop - MTR tool | ||
+ | *Number of active sessions on device | ||
+ | *Packet/Frame size | ||
+ | *Number of ACL on device | ||
+ | *Wireless is slower + wireless noise | ||
+ | *Duplex | ||
+ | *Cable | ||
+ | *Link type overhead + MTU | ||
+ | *Aggregated interfaces - hashing type (source+destination IP) | ||
+ | *CPU and RAM low especially tunneling encryption (AES-CBC not paralelized) | ||
+ | *Rate limiting | ||
+ | *No offloading | ||
+ | |||
+ | == MTU == | ||
+ | |||
+ | MTU MSS | ||
+ | [https://www.michaelfmcnamara.com/files/Contivity%20MTU%20and%20TCP%20MSS%20clamping.pdf Article MSS/MTU] | ||
+ | |||
Testing max MTU | Testing max MTU | ||
+ | |||
The important thing to remember is that an ICMP header is 8 bits so the ping test from CMD should be whatever number is your max without fragmenting PLUS 8 which gives your value for the router. | The important thing to remember is that an ICMP header is 8 bits so the ping test from CMD should be whatever number is your max without fragmenting PLUS 8 which gives your value for the router. | ||
+ | |||
+ | [https://www.sonicwall.com/support/knowledge-base/set-mtu-in-vpn-environment-in-case-of-throughput-issues/170705131319789/ Testing Max MTU/MSS] |
Latest revision as of 21:50, 17 August 2021
"Not working" network
- Duplex
- Cable
- Firewall - disable it
- DNS filtering - public DNS
- ISP outage - ping its address
- Path outage - MTR tool
- ARP old record
- MAC collision
- STP loop/Broadcast storm
- Route missing
- LACP/PAGP must be on both ends configured
- Zombie process and station or froze
- Local firewall on device, or network type (windows-public)
- NAT
- Cache browser - try incognito mode
Slow network
- Path drop - MTR tool
- Number of active sessions on device
- Packet/Frame size
- Number of ACL on device
- Wireless is slower + wireless noise
- Duplex
- Cable
- Link type overhead + MTU
- Aggregated interfaces - hashing type (source+destination IP)
- CPU and RAM low especially tunneling encryption (AES-CBC not paralelized)
- Rate limiting
- No offloading
MTU
MTU MSS Article MSS/MTU
Testing max MTU
The important thing to remember is that an ICMP header is 8 bits so the ping test from CMD should be whatever number is your max without fragmenting PLUS 8 which gives your value for the router.