A long long time ago, BGP implementations would use a Maximum Segment Size (MSS) of 536 bytes for BGP peerings. Why 536? Because in RFC 791, the original IP RFC, the maximum length of a datagram is defined as follows:
PMTUD in MPLS-enabled Networks
In the previous post on MSS, MSS Clamping, PMTUD, and MTU, we learned how PMTUD is performed by setting the Don’t fragment flag in the IP header which leads to the device that needs to perform fragmentation dropping the packet
MSS, MSS Clamping, PMTUD, and MTU
Maximum Segment Size (MSS) and MSS clamping are concepts that can be confusing. How do they relate to the MTU (Maximum Transmission Unit)? Before we setup a lab to demonstrate these concepts, let’s give some background. Note that this entire