Network

MTU / MSS Path Calculator

Calculate how much each tunnel or encapsulation layer consumes from your interface MTU, the effective TCP MSS, and the DF ping probe size. For SRE, SD-WAN, and k8s CNI engineers.

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Quick start

Call this tool from your code in three languages.

cURL

curl -X POST 'https://api.elysiatools.com/en/api/tools/mtu-and-mss-path-calculator' \
  -H 'Content-Type: application/json' \
  -d '{"mtu":1500,"encapsulationStack":"pppoe","innerIpVersion":"ipv4","tcpHeader":20,"customOverhead":0}'

API reference

Send a POST request with your inputs as JSON. File parameters require a separate upload first.

Endpoint

HTTP

POST https://api.elysiatools.com/en/api/tools/mtu-and-mss-path-calculator

Parameters

Name	Type	Required	Description
mtu	number	Yes	—
encapsulationStack	text	No	Comma-separated list of layers, outermost first. Valid values: vlan, qinq, pppoe, gre, gre_checksum, vxlan, geneve, wireguard4, wireguard6, ipsec_transport, ipsec_tunnel.
innerIpVersion	select	No	—
tcpHeader	number	No	—
customOverhead	number	No

MCP integration

Add this tool to your Model Context Protocol server so AI agents can list and call it.

Server configuration

Add this block to your MCP client configuration:

mcp.json

{
  "mcpServers": {
    "elysiatools-mtu-and-mss-path-calculator": {
      "name": "mtu-and-mss-path-calculator",
      "description": "Calculate how much each tunnel or encapsulation layer consumes from your interface MTU, the effective TCP MSS, and the DF ping probe size. For SRE, SD-WAN, and k8s CNI engineers.",
      "baseUrl": "https://api.elysiatools.com/mcp/sse?toolId=mtu-and-mss-path-calculator",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

List available tools

After connecting to the SSE endpoint, list the exposed tools:

tools/list

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/list"
}

Call this tool

Invoke the tool by its id, passing arguments built from its parameters:

tools/call

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "mtu-and-mss-path-calculator",
    "arguments": {
  "mtu": 1500,
  "encapsulationStack": "pppoe",
  "innerIpVersion": "ipv4",
  "tcpHeader": 20,
  "customOverhead": 0
}
  }
}

Chain multiple tools in one session with a comma-separated toolId list, e.g. /mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp (max 20).

Questions or issues? Contact [email protected]

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