QSolved Question: We have a Microwave wireless bridge connecting two 3750 switches. The wireless bridge is connected to a layer 3 port on the 3750 at each end and all is working fine today. We have some application requirements that we need to connect the wireless bridge to a layer 2 port, basically a trunk port on the 3750 at each end. Please see attached diagram.Has anyone done this before ?
Qsolved Answer : I've seen this done before where the wireless bridge simply acts as a transport mechanism. If you have a stable microwave link, there's no real issues but obviously this type of set up is more susceptible to interference issues.
Example: Figure 4 outdoor wireless VLANs deployment with Cisco equipment.Click here for the reference link.
Points of interest
- Be aware of any limitations with MTU for your microwave link and ensure it can accomodate any extra bytes if you are using 802.1q trunking
18bytes for ethernet header inc CRC
4 byte for the 802.1q tag
1500bytes for the IP MTU
total = 1522bytes.
Brain storming a little
- unstable trunk links will affect switches that carry the same VLANS as the trunk link - typical Layer 2 spanning-tree type issues
- if you intend to use a redundant links, you'll need to consider the fact that if the wireless goes down, the links on the switch will stay up, potentially black holing traffic, where as Layer 3 routing protocols have hello packets which could detect if the link is down.
You could use probes and scripts such as EEM to automate these kinds of things.