{"id":368,"date":"2018-10-24T01:09:54","date_gmt":"2018-10-24T01:09:54","guid":{"rendered":"http:\/\/feralpacket.org\/?p=368"},"modified":"2018-11-06T21:52:22","modified_gmt":"2018-11-06T21:52:22","slug":"protocol-priorities","status":"publish","type":"post","link":"https:\/\/feralpacket.org\/?p=368","title":{"rendered":"Protocol Priorities"},"content":{"rendered":"

Protocol Priorities<\/strong><\/p>\n

Generally, but not always:<\/strong><\/p>\n

\n – Layer 2<\/p>\n

\n -> Lower is better
\n -> PAgP port priority, higher is better<\/p><\/blockquote>\n

– IGPs and layer 3<\/p>\n

\n -> Higher is better
\n -> OSPF has an exception<\/p><\/blockquote>\n

– BGP<\/p>\n

\n -> There is a high \/ low cutoff<\/p><\/blockquote>\n

– Multicast<\/p>\n

\n -> If the protocol has “Router” in the name, then higher is better
\n -> Think “Router” -> “IGP”
\n -> Otherwise, lower is better<\/p><\/blockquote>\n<\/blockquote>\n

Spanning-tree Protocol (STP):<\/strong><\/p>\n

\n – Root Bridge<\/p>\n

\n -> Lowest bridge ID<\/p>\n

\n -> Switch priority and MAC address<\/p><\/blockquote>\n

-> Lowest priority selected
\n -> Default is 32768
\n -> Range (increments of 4096) 0, 4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 45056, 49152, 53248, 57344, and 61440<\/p>\n

\n -> SW1(config)#spanning-tree vlan 1-4094 root primary<\/strong><\/em>
\n -> SW1(config)#spanning-tree vlan 1-4094 root secondary<\/strong><\/em>
\n -> SW1(config)#spanning-tree vlan 1-4094 priority 4096<\/strong><\/em>
\n -> SW1(config)#spanning-tree mst 1 root primary<\/strong><\/em>
\n -> SW1(config)#spanning-tree mst 1 root secondary<\/strong><\/em>
\n -> SW1(config)#spanning-tree mst 1 priority 4096<\/strong><\/em><\/p><\/blockquote>\n

-> Lowest base MAC address<\/p><\/blockquote>\n

– Root Port<\/p>\n

\n -> Lowest root bridge ID
\n -> Lowest cost path to the root bridge
\n -> Default<\/p>\n

\n -> 1000 Mb\/s: 4
\n -> 100 Mb\/s: 19
\n -> 10 Mb\/s: 100<\/p><\/blockquote>\n

-> Range 1 to 200000000<\/p>\n

\n -> SW1(config-if)#spanning-tree cost 3<\/strong><\/em>
\n -> SW1(config-if)#spanning-tree vlan 1-4094 cost 3<\/strong><\/em>
\n -> SW1(config-if)#spanning-tree mst 1 cost 3<\/strong><\/em><\/p><\/blockquote>\n

-> Lowest designated bridge ID
\n -> Lowest designated path cost
\n -> Lowest received physical port number or port-id
\n -> Default is 128
\n -> Range (increments of 16) 0, 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208, 224, and 240.
\n -> Which is in the format of “.\u201d<\/p>\n

\n -> SW1(config-if)#spanning-tree port-priority 112<\/strong><\/em>
\n -> SW1(config-if)#spanning-tree vlan 1-4094 port-priority 112<\/strong><\/em>
\n -> SW1(config-if)#spanning-tree mst 1 port-priority 112<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– Designated Port<\/p>\n

\n -> Assigned to the port of the switch on the segment with the:<\/p>\n

\n -> Lowest cost path to the root bridge
\n -> Lowest neighbor bridge ID
\n -> Lowest received port-priority<\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n

Link Aggregation Control Protocol (LACP):<\/strong><\/p>\n

\n – Master \/ Slave System Priority<\/p>\n

\n -> Lowest system priority selected
\n -> Default is 32768
\n -> Range is 0 – 65535<\/p>\n

\n -> SW1(config)#lacp system-priority 32767<\/strong><\/em><\/p><\/blockquote>\n

-> Lowest MAC address
\n -> Lowest Port-ID<\/p><\/blockquote>\n

– Port Priority<\/p>\n

\n -> Lowest priority selected
\n -> Default is 32768
\n -> Range is 0 – 65535<\/p>\n

\n -> SW1(config-if)#lacp port-priority 32767<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n

Port Aggregation Protocol (PAgP):<\/strong><\/p>\n

\n – Port Priority<\/p>\n

\n -> Highest priority selected
\n -> Default is 128
\n -> Range 0 to 255<\/p>\n

\n -> SW1(config-if)#pagp port-priority 129<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n

Hot Standby Router Protocol (HSRP):<\/strong><\/p>\n

\n – Highest priority selected
\n – Default is 100
\n – Range is 0 to 255<\/p>\n

\n -> SW1(config-if)#standby 1 priority 101<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

Virtual Router Redundancy Protocol (VRRP):<\/strong><\/p>\n

\n – Highest priority selected
\n – Default is 100
\n – Range is 1 to 254<\/p>\n

\n -> SW1(config-if)#vrrp 1 priority 101<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

Gateway Load Balancing Protocol (GLBP):<\/strong><\/p>\n

\n – Highest priority selected
\n – Default is 100
\n – Range is 1 to 255<\/p>\n

\n -> SW1(config-if)#glbp 1 priority 101<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

Intermediate System to Intermediate System (IS-IS):<\/strong><\/p>\n

\n – Designated Intermediate System (DIS)<\/p>\n

-> Highest priority selected
\n -> Default is 64
\n -> Range 0 – 127<\/p>\n

\n -> R1(config-if)#isis priority 65<\/strong><\/em>
\n -> R1(config-if)#isis priority 65 level-1<\/strong><\/em>
\n -> R1(config-if)#isis priority 65 level-2<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n

Open Shortest Path First (OSPF):<\/strong><\/p>\n

\n – Designated Router (DR) \/ Backup Designated Router (BDR) Election<\/p>\n

\n -> Highest priority selected
\n -> Default is 1
\n -> Range 0 – 255<\/p>\n

\n -> R1(config-if)#ip ospf priority 2<\/strong><\/em>
\n -> R1(config-if)#ipv6 ospf neighbor 12::2 priority 2<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– EXSTART Master \/ Slave Election<\/p>\n

\n -> Higher router-id selected
\n -> R1(config-router)#router-id 0.0.0.2<\/strong><\/em><\/p><\/blockquote>\n

– Forwarding Address<\/p>\n

\n -> Lowest IP address
\n -> When dealing with LSA Type 4 and there are multiple paths<\/p>\n

\n -> Broadcast network<\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n

Border Gateway Protocol (BGP):<\/strong><\/p>\n

\n – Weight<\/p>\n

\n -> Higher value selected
\n -> Default is 0 for received routes
\n -> Default is 32768 for locally generated routes <\/p>\n

\n -> R1(config)#route-map WEIGHT permit 10<\/strong><\/em>
\n -> R1(config-route-map)#set weight 1<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 route-map WEIGHT in<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 default-originate route-map WEIGHT in<\/strong><\/em>
\n -> R1(config)#route-map WEIGHT_LOCAL permit 10<\/strong><\/em>
\n -> R1(config-route-map)#set weight 32769<\/strong><\/em>
\n -> R1(config-router)#network 1.1.1.0 mask 255.255.255.0 route-map WEIGHT_LOCAL<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– Local Preference<\/p>\n

\n -> Higher value selected
\n -> Default is 100
\n -> Range 0 – 4294967295<\/p>\n

\n -> R1(config-router)#bgp default local-preference 101<\/strong><\/em>
\n -> R1(config)#route-map LP permit 10<\/strong><\/em>
\n -> R1(config-route-map)#set local-preference 101<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 route-map LP in<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 default-originate route-map LP in<\/strong><\/em>
\n -> R1(config-router)#redistribute eigrp 1 route-map LP<\/strong><\/em>
\n -> R1(config-router)#redistribute ospf 1 route-map LP match internal external 1 external 2<\/strong><\/em>
\n -> R1(config-router)#network 1.1.1.0 mask 255.255.255.0 route-map LP<\/strong><\/em>
\n -> R1(config-router)#aggregate-address 1.1.2.0 255.255.255.252 attribute-map LP<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

* * * * High \/ Low (or shortest) Cutoff * * * *<\/strong><\/p>\n

– AS-PATH<\/p>\n

\n -> Lowest number of organizations traversed is better
\n -> Shortest<\/p>\n

\n -> R1(config)#route-map PREPEND permit 10<\/strong><\/em>
\n -> R1(config-route-map)#set as-path prepend 100 100<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 route-map PREPEND out<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– ORIGIN<\/p>\n

\n -> Lowest type<\/p><\/blockquote>\n

– Multi-Exit Discriminator (MED)<\/p>\n

\n -> Lowest value selected
\n -> Default is 0 for received routes
\n -> Default is IGP metric for locally generated routes (network or redistribute commands)
\n -> Range 0 to 65535<\/p>\n

\n -> R1(config)#route-map MED permit 10<\/strong><\/em>
\n -> R1(config-route-map)#set metric 1<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 route-map MED out<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 default-originate route-map MED out<\/strong><\/em>
\n -> R1(config-router)#redistribute eigrp 1 metric 100<\/strong><\/em>
\n -> R1(config-router)#redistribute ospf 1 metric 100 match internal external 1 external 2<\/strong><\/em>
\n -> R1(config-router)#redistribute eigrp 1 route-map MED<\/strong><\/em>
\n -> R1(config-router)#redistribute ospf 1 route-map MED match internal external 1 external 2<\/strong><\/em>
\n -> R1(config-router)#network 1.1.1.0 mask 255.255.255.0 route-map MED<\/strong><\/em>
\n -> R1(config-router)#aggregate-address 1.1.2.0 255.255.255.252 attribute-map MED<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– IGP Metric<\/p>\n

\n -> Lowest<\/p><\/blockquote>\n

– Extended Community Cost<\/p>\n

\n -> Lowest extended cost community is selected
\n -> IGP point of insertion (default)
\n -> Default is 2147483647
\n -> Range 0 and 4294967295<\/p>\n

\n -> R1(config)#route-map EXTCOMMUMITYCOST permit 10<<\/strong>\/em>
\n -> R1(config-route-map)#set extcommunity cost 1 1<\/strong><\/em>
\n -> R1(config)#route-map EXTCOMMUMITYCOST permit 10<\/strong><\/em>
\n -> R1(config-route-map)#set extcommunity cost igp 1 1<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 route-map EXTCOMMUMITYCOST out<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 default-originate route-map EXTCOMMUMITYCOST out<\/strong><\/em>
\n -> R1(config-router)#redistribute eigrp 1 route-map EXTCOMMUMITYCOST<\/strong><\/em>
\n -> R1(config-router)#redistribute ospf 1 route-map EXTCOMMUMITYCOST match internal external 1 external 2<\/strong><\/em>
\n -> R1(config-router)#network 1.1.1.0 mask 255.255.255.0 route-map EXTCOMMUMITYCOST<\/strong><\/em>
\n -> R1(config-router)#aggregate-address 1.1.2.0 255.255.255.252 attribute-map EXTCOMMUMITYCOST<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– Multipath External Paths<\/p>\n

\n -> Path that was received first<\/p><\/blockquote>\n

– Cluster Length<\/p>\n

\n -> Shortest<\/p><\/blockquote>\n

– Router-id<\/p>\n

\n -> Lowest<\/p><\/blockquote>\n

– Neighbor Address<\/p>\n

\n -> Lowest<\/p><\/blockquote>\n

– Extended Community Cost, pre-best path<\/p>\n

\n -> Lowest extended community cost is selected
\n -> Pre-best path point on insertion
\n -> Default is 2147483647
\n -> Range 0 and 4294967295<\/p>\n

\n -> R1(config)#route-map EXTCOMMCOST_PRE permit 10<\/strong><\/em>
\n -> R1(config-route-map)#set extcommunity cost pre-bestpath 1 1<\/strong>
\n -> R1(config-router)#neighbor 1.1.1.1 route-map EXTCOMMCOST_PRE out<\/strong><\/em>
\n -> R1(config-router)#neighbor 1.1.1.1 default-originate route-map EXTCOMMCOST_PRE out<\/strong><\/em>
\n -> R1(config-router)#redistribute eigrp 1 route-map EXTCOMMCOST_PRE<\/strong><\/em>
\n -> R1(config-router)#redistribute ospf 1 route-map EXTCOMMCOST_PRE match internal external 1 external 2<\/strong><\/em>
\n -> R1(config-router)#network 1.1.1.0 mask 255.255.255.0 route-map EXTCOMMCOST_PRE<\/strong><\/em>
\n -> R1(config-router)#aggregate-address 1.1.2.0 255.255.255.252 attribute-map EXTCOMMCOST_PRE<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n

Multicast:<\/strong><\/p>\n

\n – Multiple Rendezvous Point (RP) candidate<\/p>\n

\n -> Lowest priority selected
\n -> Default 0
\n -> Range 0 to 255<\/p>\n

\n -> R1(config)#ip pim rp-candidate fa0\/0 priority 1<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– Multiple Bootstrap Routers (BSR)<\/p>\n

\n -> Highest priority selected
\n -> Default 0
\n -> Range 0 to 255<\/p>\n

\n -> R1(config)#ip pim bsr-candidate fa0\/0 0 1<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– Designated Router (DR)<\/p>\n

\n -> Highest priority selected
\n -> Default, command is disabled (no priority set)
\n -> Range 0 to 4294967294<\/p>\n

\n -> SW1(config-if)#ip pim dr-priority 1<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– IGMP Querier Election<\/p>\n

\n -> Lowest IP address selected<\/p><\/blockquote>\n<\/blockquote>\n

MPLS-TE:<\/strong><\/p>\n

\n – Setup Priority<\/p>\n

\n -> Lowest priority selected
\n -> Default is 7
\n -> Range 0 to 7<\/p>\n

\n -> R1(config-if)#tunnel mpls traffic-eng priority 6<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n

– Holding Priority<\/p>\n

-> Lowest priority selected
\n -> Default is 7
\n -> Range 0 to 7<\/p>\n

\n -> R1(config-if)#tunnel mpls traffic-eng priority 6 6<\/strong><\/em><\/p><\/blockquote>\n<\/blockquote>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"

Protocol Priorities Generally, but not always: – Layer 2 -> Lower is better -> PAgP port priority, higher is better – IGPs and layer 3 -> Higher is better -> OSPF has an exception – BGP -> There is a high \/ low cutoff – Multicast -> If the protocol has “Router” in the name, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-368","post","type-post","status-publish","format-standard","hentry","category-ccie"],"_links":{"self":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/368","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=368"}],"version-history":[{"count":24,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/368\/revisions"}],"predecessor-version":[{"id":861,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/368\/revisions\/861"}],"wp:attachment":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=368"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=368"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=368"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}