{"id":416,"date":"2018-10-26T21:43:02","date_gmt":"2018-10-26T21:43:02","guid":{"rendered":"http:\/\/feralpacket.org\/?p=416"},"modified":"2018-10-26T22:54:18","modified_gmt":"2018-10-26T22:54:18","slug":"l3vpn-loop-prevention-features-notes","status":"publish","type":"post","link":"https:\/\/feralpacket.org\/?p=416","title":{"rendered":"L3VPN Loop Prevention Features Notes"},"content":{"rendered":"

L3VPN Loop Prevention Featurees<\/span><\/p>\n

OSPF<\/span><\/p>\n

\n– Uses DOWN-BIT<\/p>\n

\n\u00a0\u00a0\u00a0\u00a0 -> When a PE router receives an update on a VRF interface, it performs a DOWN-BIT operation<\/p>\n

\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -> If the down-bit is not set in the update packet, it is set by the PE router<\/p>\n

\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -> If the down-bit is set, the PE router drops the packet<\/p>\n

\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -> Down-bit checking is only done on type 3 LSAs (Inter-Area)<\/p>\n

\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -> Doesn’t work for type 1 LSAs used by sham-links<\/p>\n

\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -> No configuration required\n<\/p>\n

BGP<\/span><\/p>\n

\n– Can use extended community called “site-of-origin”<\/p>\n

\n\u00a0\u00a0\u00a0\u00a0 -> Can be set on incoming VRF interface<\/p>\n

\n\u00a0\u00a0\u00a0\u00a0 -> SoO = 64 bit value represented at X:Y<\/a><\/p>\n

\n\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 -> Must be different on each PE router\n<\/p>\n

\nR1(config)# router bgp 100<\/span><\/p>\n

address-family ipv4 vrf c1b1<\/span><\/p>\n

\n\u00a0 neighbor 14.0.0.4 soo 100:100<\/span><\/p>\n

\nR3(config)# router bgp 100<\/span><\/p>\n

address-family ipv4 vrf c1b2<\/span><\/p>\n

\n\u00a0 neighbor 35.0.0.5 soo 200:200<\/span><\/p>\n

<\/p>\n

SoO value should be the same on PE routers connected to the same branch.<\/p>\n

EIGRP<\/span><\/p>\n

\u00a0– Can use “site-of-origin” to prevent loops<\/p>\n

R1(config)# router-map SOO<\/span><\/p>\n

\u00a0set ext-community soo 100:100<\/span><\/p>\n

int s0\/0<\/span><\/p>\n

\u00a0ip vrf sitemap SOO<\/span><\/p>\n

Sitemap<\/p>\n

\u00a0– If SoO is not set, then set<\/p>\n

\u00a0– If SoO is set, then drop<\/p>\n","protected":false},"excerpt":{"rendered":"

L3VPN Loop Prevention Featurees<\/p>\n","protected":false},"author":1,"featured_media":415,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[33,32],"class_list":["post-416","post","type-post","status-publish","format-standard","hentry","category-ccie","tag-l3vpn","tag-mpls"],"_links":{"self":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/416","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=416"}],"version-history":[{"count":3,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/416\/revisions"}],"predecessor-version":[{"id":420,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/posts\/416\/revisions\/420"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=\/wp\/v2\/media\/415"}],"wp:attachment":[{"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=416"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=416"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/feralpacket.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=416"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}