Access Layer for the WAN Network

Access Layer for the WAN Network
In the WAN hierarchy, the Access layer consists of mainly lower speed routers that connect a
remote site to a Distribution layer router within the same geographic region. The speed of the
router depends upon the bandwidth requirements at the remote site. Layer 3 access control is
provided at this layer, as is the optional marking of packets.
There can be a backup connection to a second Distribution layer router within the same
region, which allows redundancy from the remote site in case a circuit is disrupted. To further
enhance redundancy, a second Access layer router can be deployed at the remote site,
which is connected to a second Distribution layer router in case the router or circuit is disrupted.
In this case, a protocol such as HSRP, VRRP, or GLBP is used to allow these routers
to appear as a single router to make the failover transparent to the end users. These protocols
allow two or more routers to appear as one to back each other up in case one fails or
to distribute the routing load among a number of routers. The level of redundancy needed
depends upon the number of users that will be affected and the business importance of this
remote site.