Tunnel MTU size of R5.2.1 is 4 bytes smaller than R3.6.2
Summary
After upgrading SZ to R5.2.1, tunnel MTU size became smaller than R3.6.2.Question
Is it a software defect that tunnel MTU size was smaller than previous release?Customer Environment
R5.2.1 SZ-100Resolution
Tunnel MTU size calculation was changed after R5.1.1.The following is tunnel MTU size when the interface MTU size is 1500.
| Tunnel type (IPv4) | R5.1 – GRE MTU | R.5.1.1 – GRE MTU |
| eth_ipv4_rksgre | 1450 | 1446 |
| eth_ipv4_rksgre + Encryption | 1440 | 1440 |
| eth_ipv4_udp_rksgre | 1442 | 1438 |
| eth_ipv4_udp_rksgre +Encryption | 1440 | 1424 |
AP side has one more check when sending MTU size to DP.
AP has a check and maximum size will be 1440, so actual tunnel MTU size will be 1440 even if AP CLI output shows 1446 for eth_ipv4/rksgre.
---
rkscli: get mtu gre1
gre1 MTU: 1446
Ok
---
| Tunnel type (IPv4) | R5.1 – GRE MTU | R.5.1.1 – GRE MTU |
| eth_ipv4_rksgre | 1450 | 1440 |
| eth_ipv4_rksgre + Encryption | 1440 | 1440 |
| eth_ipv4_udp_rksgre | 1442 | 1438 |
| eth_ipv4_udp_rksgre +Encryption | 1440 | 1424 |
Article Number:
000011560
Updated:
April 12, 2021 07:53 PM (about 4 years ago)
Tags:
Configuration, SmartCell Gateway
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