MAC Access List EtherType

When configuring MAC Access Lists, it is possible to filter out frames based on the value found in the EtherType field of the Ethernet frame. However, depending upon the IOS version and the platform being used, you may find that there is a limitation as to what EtherTypes can be filtered.

On some platforms, it is possible to specify any value for the EtherType. On others, only specific values are allowed.

For example, examine this context sensitive help:

SW1(config)#mac access-list extended NO-IPV6 SW1(config-ext-macl)#permit any any ? <0-65535> An arbitrary EtherType in decimal or hex aarp EtherType: AppleTalk ARP amber EtherType: DEC-Amber appletalk EtherType: AppleTalk/EtherTalk cos CoS value dec-spanning EtherType: DEC-Spanning-Tree decnet-iv EtherType: DECnet Phase IV diagnostic EtherType: DEC-Diagnostic dsm EtherType: DEC-DSM etype-6000 EtherType: 0x6000 etype-8042 EtherType: 0x8042 lat EtherType: DEC-LAT lavc-sca EtherType: DEC-LAVC-SCA lsap LSAP value mop-console EtherType: DEC-MOP Remote Console mop-dump EtherType: DEC-MOP Dump msdos EtherType: DEC-MSDOS mumps EtherType: DEC-MUMPS netbios EtherType: DEC-NETBIOS protocol-family An Ethernet protocol family vines-echo EtherType: VINES Echo vines-ip EtherType: VINES IP vlan Vlan Id xns-idp EtherType: XNS IDP

Notice that there are many options that can be chosen using keywords that refer to specific EtherType values. However, you are also given the option (stated on the first line) of an arbitrary EtherType in decimal or hex. So any value can be applied.

On other platforms, you may see something like this:

SW1(config)#mac access-list extended NO-IPV6 SW1(config-ext-macl)#permit any any ? aarp EtherType: AppleTalk ARP amber EtherType: DEC-Amber appletalk EtherType: AppleTalk/EtherTalk dec-spanning EtherType: DEC-Spanning-Tree decnet-iv EtherType: DECnet Phase IV diagnostic EtherType: DEC-Diagnostic dsm EtherType: DEC-DSM etype-6000 EtherType: 0x6000 etype-8042 EtherType: 0x8042 lat EtherType: DEC-LAT lavc-sca EtherType: DEC-LAVC-SCA mop-console EtherType: DEC-MOP Remote Console mop-dump EtherType: DEC-MOP Dump msdos EtherType: DEC-MSDOS mumps EtherType: DEC-MUMPS netbios EtherType: DEC-NETBIOS vines-echo EtherType: VINES Echo vines-ip EtherType: VINES IP xns-idp EtherType: XNS IDP SW1(config-ext-macl)#permit any any

Notice here that the option of an arbitrary EtherType value is not given. Only the specified EtherTypes can be configured. Depending on the platform you are using you will be given varying options.

Links:

https://forum.networklessons.com/t/vlan-access-list-vacl/1155/59?u=lagapidis

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/security/m1/sec-m1-cr-book/sec-cr-p1.html#wp4193720440